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Pololu Maestro Servo Controller User`s Guide

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1. 9 Maestro Settings Limitations Page 71 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 10 Related Resources This section lists resources that might help you use the Maestro Please note that these resources are of varying quality and most are not tested or supported by Pololu Tutorials and example code e Sample Project Simple Hexapod Walker http www pololu com docs 0J42 Pololu Mini Maestro and Arduino Tutorial http www darrenfeetham com 18ssc html Obstacle avoider robot http forum pololu com viewtopic php f 2 amp t 2756 This robot features a Maestro as its main controller e Mini Maestro 24 as an LCD Driver http forum pololu com viewtopic php f 2 amp t 7402 e PMCtrl https github com gNSortino PMCtrl This is a library for the Arduino platform that uses the SoftwareSerial library to control the Maestro node pololumaestro https npmjs org package pololu maestro This is a module for the Node js platform for controlling a Maestro over its serial interface e polstro https code google com p polstro This is a cross platform C library for controlling a Maestro over its serial interface e RPi Android HTMLS Realtime Servo Control http martinsant net page_id 479 This project features a Python program running on a Raspberry Pi that controls a Maestro over its serial interface C UDP server http forum pololu com viewtopic php p 38801 p38801 This serve
2. The CRC computation is basically a carryless long division of a CRC polynomial 0x91 into your message expressed as a continuous stream of bits where all you care about is the remainder The Maestro uses CRC 7 which means it uses an 8 bit polynomial and as a result produces a 7 bit remainder This remainder is the lower 7 bits of the CRC byte you tack onto the end of your command packets 9 The CRC implemented on the Maestro is the same as the one on the jrk http www pololu com product 1392 and qik http www pololu com product 1110 motor controller but differs from that on the TReX http www pololu com product 777 motor controller Instead of being done MSB first the computation is performed LSB first to match the order in which the bits are transmitted over the serial line In standard binary notation the number 0x91 is written as 10010001 However the bits are transmitted in this order 1 0 0 0 1 0 0 1 so we will write it as 10001001 to carry out the computation below The CRC 7 algorithm is as follows 1 Express your 8 bit CRC 7 polynomial and message in binary LSB first The polynomial 0x91 is written as 10001001 2 Add 7 zeros to the end of your message 3 Write your CRC 7 polynomial underneath the message so that the LSB of your polynomial is directly below the LSB of your message 4 Ifthe LSB of your CRC 7 is aligned under a 1 XOR the CRC 7 with the message to get a new message if the L
3. 4000 1 servo 500 delay 1 minus subtract 1 from the number of times remaining repeat Note that BEGIN WHILE REPEAT loops are similar to the while loops of many other languages But just like everything else in the Maestro script language the WHILE comes after its argument For conditional actions an IF ELSE ENDIF structure is useful Suppose we are building a system with a sensor on channel 3 and we want to set servo 5 to 6000 1 5 ms if the input value is less than 512 about 2 5 V Otherwise we will set the servo to 7000 1 75 ms The following code accomplishes this relatively complicated task 3 get_position get the value of input 3 as a number from 0 to 1023 512 less than test whether it is less than 512 gt 1 if true 0 if false if 6000 5 servo this part is run when input3 lt 512 else 7000 5 servo this part is run when input3 gt 512 endif As in most languages the ELSE section is optional Note again that this seems at first to be backwards relative to other languages since the IF comes after the test The WHILE and IF structures are enough to create just about any kind of script However there are times when it is just not convenient to think about what you are trying to do in terms of a loop or a branch If you just want to jump directly from one part of code to another you may use a GOTO It works like this 6 The Maestro Scripting Language Page 51 of 73 Pololu Maestro Servo Controller User
4. 80 frame repeat loads a frame specified in 25 us units sub frame 100 times 0 servo 500 delay return This program is 29 bytes long with 3 bytes used per position and 14 bytes of overhead Note that we could get the same efficiency if we used the SERVO_8BIT command which takes a one byte argument from 0 to 254 We can go even smaller by putting all of the numbers together Move servo 0 to five different positions in a loop begin 80 70 60 50 40 frame frame frame frame frame repeat loads a frame specified in 25 us units sub frame 100 times 0 servo 500 delay return If you step through this version program you will also notice that all five numbers are placed on the stack in a single step this is because the compiler can use a single command to put multiple numbers on the stack Using a single command for multiple numbers saves space we are now down to just 26 bytes Only 12 bytes are used for the 5 frames for an average of 2 4 bytes per frame This is probably compact enough by duplicating this structure we could fit 420 different positions into the 1024 byte program memory of the Micro Maestro However the code can get even smaller Consider this script which uses 31 frames to make a smooth back and forth motion Moves servo in a sine wave between 1 and 2 ms begin 60 64 68 71 74 77 79 80 80 79 78 76 73 70 66 62 58 54 50 47 44 42 41 40 40 41 43 46 49 52 56 all frames repeat sub all_frames begin
5. but it does not work with the Microsoft C compiler For Windows specific example code that works with either compiler see Section 5 h 2 Uses POSIX functions to send and receive data from a Maestro NOTE The Maestro s serial mode must be set to USB Dual Port NOTE You must change the const char device line below include lt fcntl h gt include lt stdio h gt include lt unistd h gt ifdef WIN32 define O NOCTTY 0 else include lt termios h gt fendif Gets the position of a Maestro channel See the Serial Servo Commands section of the user s guide int maestroGetPosition int fd unsigned char channel unsigned char command 0x90 channel if write fd command sizeof command 1 perror error writing return 1 unsigned char response 2 if read fd response 2 2 perror error reading return 1 return response 0 256 response 1 Sets the target of a Maestro channel See the Serial Servo Commands section of the user s guide The units of target are quarter microseconds int maestroSetTarget int fd unsigned char channel unsigned short target unsigned char command 0x84 channel target amp Ox7F target gt gt 7 Ox7F if write fd command sizeof command 1 perror error writing return 1 return 0 int main Open the Maestro s virtual COM port const char device USBSERO00
6. other commands Since there is no restriction on the high bit the position is formatted as a standard little endian two byte unsigned integer For example a position of 2567 corresponds to a response 0x07 Ox0A Note that the position value returned by this command is equal to four times the number displayed in the Position box in the Status tab of the Maestro Control Center Get Moving State Compact protocol 0x93 Pololu protocol OxAA device number 0x13 Response 0x00 if no servos are moving 0x01 if servos are moving 5 Serial Interface Page 43 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation This command is used to determine whether the servo outputs have reached their targets or are still changing and will return as long as there is at least one servo that is limited by a speed or acceleration setting still moving Using this command together with the Set Target command you can initiate several servo movements and wait for all the movements to finish before moving on to the next step of your program Get Errors Compact protocol 0xA1 Pololu protocol OxAA device number 0x21 Response error bits 0 7 error bits 8 15 Use this command to examine the errors that the Maestro has detected Section 4 b lists the specific errors that can be detected by the Maestro The error register is sent as a two byte response immediately after the command is received then all the error bits are cleared F
7. proloco send commands to the Maestro The Maestro s responses to those commands will be sent to the Command Port but not the TX line Bytes received on the RX line will be sent to the Command Port but will not be interpreted as ae command bytes by the Maestro The baud rate mode USB Chained you set in your terminal program when opening the Command Port determines the baud rate used to receive and send bytes on RX and TX The TTL Port is not used This mode allows a single COM port on your computer to control multiple Maestros or a Maestro and other devices that have a compatible protocol command The USB Chained serial mode UART In this mode the TX and RX lines can be HostPC Pololu USB device Microcontroller used to send commands to the Maestro and receive responses from it Any byte received on RX will be sent to the Command Port but bytes sent from the Command Port will be ignored The TTL Port is not used The baud rate on TX and RX can either be not used automatically detected by the Maestro when a 0xAA byte is received on RX or it can be set to a fixed l value specified in bits per second bps This mode allows you to control the Maestro and send bytes to a serial program on the computer using a microcontroller or other TTL serial device command processing mode UART The UART serial mode Other serial settings Enable CRC If checked the Maestro will require a cyclic re
8. 0 11 In the Maestro Control Center under the Channel Settings tab change that channel to Input mode and click Apply Settings Next connect the potentiometer to the Maestro so that E AA ss the two ends go to GND and 5 V and the wiper connects to the signal line y lt of the channel The picture to the right shows how to connect a potentiometer to channel 0 on the Micro Maestro 6 channel servo Diagram for connecting a controller The potentiometer should have a resistance of at least 1 kilo potentiometer to the Micro Maestro ohm so that it does not draw too much current from the 5V line servo controller You can test your input by rotating the potentiometer and verifying that the Position variable as shown in the Status tab of the Maestro Control Center reflects the position of the potentiometer it should vary between approximately 255 75 and 0 Now you can read the position of the potentiometer in your script using the GET_POSITION command or over serial using the Get Position command These commands will return values between approximately 1023 and 0 7 Wiring Examples Page 67 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation LED To connect an LED to the Maestro you should first decide which channel you would like to use In the Maestro Control Center under the Channel Settings tab change that channel to Output mode and click Apply Settings Next connect the c
9. 300 599 else 6 The Maestro Scripting Language Page 59 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 8000 go to 8000 for values 600 1023 endif endif 0 servo drop remove the original copy of the pot value repeat The example above works but when the potentiometer is close to 300 or 600 noise on the analog to digital conversion can cause the servo to jump randomly back and forth A better way to do it is with hysteresis Set the servo to 4000 6000 or 8000 depending on an analog input with hysteresis begin 4000 0 300 servo_range 6000 300 600 servo range 8000 600 1023 servo_range repeat usage lt pos gt lt low gt lt high gt servo range If the pot is in the range specified by low and high keeps servo 0 at pos until the pot moves out of this range with hysteresis sub servo_range pot 2 pick less than logical_not gt low pot 2 pick greater than logical _not lt high logical_and If begin pot 2 pick 10 minus less_than logical_not gt low 10 pot 2 pick 10 plus greater_than logical_not lt high 10 logical_and while 2 pick 0 servo repeat endif drop drop drop return sub pot 1 get_position return This example uses one range for deciding where to go when making a transition then it waits for the servo to leave a slightly larger range before making another transition As long as the difference 10 in this example is larger than the amount of n
10. 3000 delay return 2001 2014 Pololu Corporation Please note that this script does not do multi tasking If a sequence is running the script will not detect other button presses until the sequence is done It is possible to make the buttons operate independently but the script would need to be much more complicated Depending on how skilled you are at writing scripts you might prefer to use multiple Maestros instead Long delays The longest delay possible with the DELAY command is approximately 32 seconds In some cases you will want to make delays much longer than that Here is an example that shows how delays of many seconds or minutes can be accomplished Moves servo 0 back and forth begin 4000 0 servo 10 delay minutes 8000 0 servo 10 delay minutes repeat delay by a specified sub delay seconds begin dup while minus 1000 delay repeat drop return delay by a specified sub delay minutes begin dup while with a delay of number of seconds up to check if the count has subtract one and delay 10 minutes between motions 65535 s reached zero 1s remove the 0 from the stack and return number of minutes up to 65535 min minus 60 delay seconds subtract one and delay 1min 6 The Maestro Scripting Language Page 62 of 73 Pololu Maestro Servo Controller User s Guide repeat 2001 2014 Pololu Corporation drop return remove the 0 from the stack and return It i
11. ACM devices you have plugged in The port with the lower number should be the Command Port while the port with the higher number should be the TTL Serial Port You can use any terminal program such as kermit to send and receive bytes on those ports 3 c Using the Maestro without USB It is possible to use the Maestro as a serial servo controller without installing any USB drivers or using a PC Without using USB you will not be able to change the Maestro s settings but you can use the default settings which are suitable for many applications The default settings that the Maestro ships with are described below Default Settings e The serial mode is UART detect baud rate after you send the OxAA baud rate indication byte the Maestro will accept TTL level serial commands on the RX line The Pololu Protocol device number is 12 the Mini SSC offset is 0 and serial timeout and CRC are disabled e All channels are configured as servos with a minimum pulse with of 992 us and a maximum pulse width of 2000 ys 3 Getting Started Page 20 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation The 8 bit neutral point is 1500 us and the 8 bit range is 476 25 us On startup or error the servos turn off no pulses are sent On startup there are no speed or acceleration limits but you can set speed and acceleration limits using serial commands The servo period is 20 ms each servo recei
12. Controller usc03b and the Mini Maestro 24 Channel USB Servo Controller usc03c 3 Download the latest version of the firmware for your type of Maestro It is important that you know which type of Maestro you have so that you can download the correct version The latest firmware versions can be downloaded here o Firmware version 1 02 for the Micro Maestro 6 Channel USB Servo Controller usc02a http www pololu com file download usc02a_v1 02 pgm file_id 0J644 34k pgm o Firmware version 1 02 for the Mini Maestro 12 Channel USB Servo Controller usc03a http www pololu com file download usc03a_v1 02 pgm file_id 0J645 39k pgm o Firmware version 1 02 for the Mini Maestro 18 Channel USB Servo Controller usc03b http www pololu com file download usc03b_v1 02 pgm file_id 0J646 42k pgm o Firmware version 1 02 for the Mini Maestro 24 Channel USB Servo Controller usc03c http www pololu com file download usc03c_v1 02 pgm file_id 0J647 43k pgm 4 Connect your Maestro to a Windows or Linux computer using a USB cable 5 Run the Maestro Control Center and connect to the Maestro by selecting its serial number in the Connected to drop down box in the upper left corner 6 If you were not able to connect to the Maestro using the Maestro Control Center double check your USB connection make sure all other devices are disconnected from the Maestro and try plugging it into several different USB ports on your computer If
13. Controller User s Guide 2001 2014 Pololu Corporation 3 b Installing Linux Drivers and Software bi Pololu Maestro Control Center File Device Edit Help Connected to feo0o00080 y Firmware version 1 01 Error code 0x0000 states lErrors channel Settings Serias Settings sequence sorgt s Name Mode Enabled The Maestro Control Center running in Ubuntu Linux You can download the Maestro Control Center and the Maestro command line utility UscCmd for Linux here Maestro Servo Controller Linux Software http www pololu com file download maestro linux 100507 tar gz file_id 03315 112k gz Unzip the tar gzip archive by running tar xzvf followed by the name of the file After following the instructions in README txt you can run the programs by executing MaestroControlCenter and UscCmd You can also download the C source code of UscCmd as part of the Pololu USB Software Development Kit http www pololu com docs 0J41 Read README txt in the SDK for more information The Maestro s two virtual serial ports can be used in Linux without any special driver installation The virtual serial ports are managed by the cdc acm kernel module whose source code you can find in your kernel s source code drivers usb class cdc acm c When you connect the Maestro to the PC the two virtual serial ports should appear as devices with names like dev ttyacmo and dev ttyacm1 the number depends on how many other
14. Pololu protocol Micro Maestro pulse length limitations high pulse rates only Y Most servos are designed for 50 Hz operation Unless you know that you need high pulse rates you can safely ignore this section The Micro Maestro has a restricted maximum pulse length for pulse rates of 67 Hz and higher The restriction depends on the Servos available setting and is enforced automatically by the Maestro Control Center The maximum pulse lengths in microseconds are given below 6 servos 5 servos 4servos 1 3 servos 67 Hz 2448 2944 3000 3000 71 Hz 2272 2736 3000 3000 77 Hz 2112 2544 3000 3000 83 Hz 1936 2336 2944 3000 91 Hz 1776 2144 2688 3000 100 Hz 1616 1936 2448 3000 Mini Maestro servo pulse length limitations high pulse rates only y Most servos are designed for 50 Hz operation Unless you know that you need high pulse rates you can safely ignore this section On the Mini Maestro 12 18 and 24 pulse rates of 200 333 Hz put restrictions on the servo pulse lengths These restrictions apply to all servo channels even if some are set to a lower pulse rate using the Period multiplier feature The following tables show allowed minimum and maximum pulse lengths in microseconds for a variety of combinations of pulse rates and servo numbers All enabled servos must always satisfy the restrictions on some table row so the easiest way to follow the restrictions is to pick a row then configure
15. The Errors tab in the Maestro Control Center The Errors tab indicates problems that the Maestro has detected while running either communications errors or errors generated by bugs in a script Each error corresponds to a bit in the two byte error register The red LED will be on as long as any of the bits in the error register are set to it can also be turned on by the led_on script command The value of the error register is displayed in the upper right corner of the main window When an error occurs the corresponding bit in the error register is set to 1 and the Maestro sends all of its servos and digital outputs to their home positions as specified in the Settings tab Section 4 e Any servos or outputs that are configured to be in the Ignore mode will not be changed The error register is cleared by the Get Errors serial command The errors and their corresponding bit numbers are listed below Serial Signal Error bit 0 A hardware level error that occurs when a byte s stop bit is not detected at the expected place This can occur if you are communicating at a baud rate that differs from the Maestro s baud rate Serial Overrun Error bit 1 A hardware level error that occurs when the UART s internal buffer fills up This should not occur during normal operation Serial RX buffer full bit 2 A firmware level error that occurs when the firmware s buffer for bytes received on the RX line is full and a byt
16. The numbers are placed on the stack at the beginning of the loop then consumed later on in execution Pay attention to the order of the numbers used here the 900 goes on the stack first and it is used last A simple servo sequence The following script shows how to direct servo 0 to five different positions in a loop Move servo 0 to five different positions in a loop begin 4000 0 servo set servo 0 to 1 00 ms 500 delay 5000 0 servo 1 25 ms 500 delay 6000 0 servo 1 50 ms 500 delay 7000 0 servo 1 75 ms 500 delay 8000 0 servo 2 00 ms 500 delay repeat 9 The serial mode must not be set to detect baud rate for this script to work In detect baud rate mode the Maestro does not enable any of the servo outputs until the start byte has been received Note that the servo positions are specified in units of 0 25 us so a value of 4000 corresponds to 1 ms The text after the is a comment it does not get programmed on to the device but it can be useful for making notes about how the program works Good comments are essential for complicated programs It is important to remember the DELAY commands without these the script will not wait at all between servo commands running the loop hundreds of times per second Compressing the sequence The program above takes 58 bytes of program space 11 bytes for each servo position and 3 for the loop At this rate we could store up to 92 servo positions in the 1024 byte memory of
17. and other electronics Read a gyro or accelerometer http www pololu com category 80 accelerometers gyros compasses from a computer for novel user interfaces Control a string of ShiftBrites http www pololu com product aM 1222 from a computer for mood lighting LS e General I O expansion for microcontroller projects Micro Maestro as the brains of a tiny e Programmable self contained Halloween or Christmas hexapod robot display controller that responds to sensors e Self contained servo tester 1 a Micro Maestro Pinout and Components USB mini B connector 5V out signal r servo power channel 0 channel 1 channel 2 channel 3 channel 4 channel 5 yellow amp red status LEDs RST board reset TX TTL serial output RX TTL serial input VIN 5 16V board power GND Micro Maestro 6 channel USB servo controller fully assembled labeled top view 9 Note This section applies to the Micro Maestro servo controller Please see Section 1 b for Mini Maestro pinout and component information The Pololu Micro Maestro 6 channel servo controller can connect to a computer s USB port via a USB A to mini B cable http www pololu com product 130 not included The USB connection is used to configure the servo controller It 1 Overview Page 7 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation can also be used to send commands to the servo controller get information about
18. mode DEVICE 1 CHANNEL 2 TARGET 3 byte printf MAx printf Sx 1 byte 0x84 byte SCHANNEL byte TARGET amp Ox7F byte TARGET gt gt 7 amp 0x7F gt SDEVICE This script can also be run on Windows but since Windows does not have bash installed by default it is easier to use UscCmd 5 Serial Interface Page 49 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 6 The Maestro Scripting Language A script is a sequence of commands that is executed by the Maestro Commands can set servo targets speeds and accelerations retrieve input values and perform mathematical computations Basic control structures looping and conditionals are available for use in making complicated scripts The Maestro script language is a simple stack based language very similar to FORTH and scripts compile to a compact bytecode in which commands and subroutine calls each take just a single byte A basic editor debugger is available in the Script tab of the Maestro Control Center application 6 a Maestro Script Language Basics Commands and the stack A program in the Maestro script language consists of a sequence of commands which act on a stack of values Values in the stack are integers from 32768 to 32767 On the Micro Maestro 6 channel servo controller there is room for up to 32 values on the stack while on the Mini Maestro servo controllers there is room for up to 126
19. or playing a sequence will Never sleep ignore USB suspend By default the Maestro s processor will go to sleep and stop all of its operations whenever it detects that it is only powered by USB no VIN supply and that the USB has entered the Suspend State However this behavior can be disabled by checking the Never sleep checkbox 5 b TTL Serial The Maestro s serial receive line RX can receive bytes when connected to a logic level 0 to 4 0 5 V or TTL non inverted serial signal The bytes sent to the Maestro on RX can be commands to the Maestro or an arbitrary stream of data that the Maestro passes on to a computer via the USB port depending on which serial mode the Maestro is in Section 5 a The voltage on the RX pin should not go below 0 V and should not exceed 5 V The Maestro provides logic level 0 to 5 V serial output on its serial transmit line TX The bytes sent by the Maestro on TX can be responses to commands that request information or an arbitrary stream of data that the Maestro is receiving from a computer via the USB port and passing on depending on which Serial Mode the Maestro is in If you aren t interested in receiving TTL serial bytes from the Maestro you can leave the TX line disconnected The serial interface is asynchronous meaning that the sender and receiver each independently time the serial bits Asynchronous TTL serial is available as hardware modules called UARTs on many microcontroller
20. run forever While the script is running the red Stop Script button will be available and the small pink triangle will jump around your source code showing you the instruction that is currently being executed If the script places data on the stack it will be visible on the right side of the tab and nested subroutine calls are counted in a label at the top of the tab To examine the operation of a script in more detail click the blue button labeled Step Script This button causes the script to execute a single instruction then stop and wait for another command By stepping through the script a single instruction at a time you can check that each part of your program does exactly what you expect it to do Setting the script to be run on startup By default the script only runs when you click the Run Script button However for many applications you will want the script to run automatically so that the Maestro can be used without a permanent USB connection Check the Run script on startup option to cause the Maestro to automatically run the script whenever it is powered up You will still be able to use the controls on the Script tab for debugging or to stop the running script 4 Using the Maestro Control Center Page 28 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation Examining the compiled code Click the View Compiled Code button to see the actual bytes that are created b
21. specifies how many numbers are consumed and added to the stack For example the PLUS command takes off two numbers and returns one so it has a stack effect of 2 1 Commands with special effects will be marked with a 6 The Maestro Scripting Language Page 52 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Keywords stack effect BEGIN none marks the beginning of a loop ends a conditional block IF ENDIF keyword description begins the alternative block in IF ELSE ENDIF goes to the label label define it with label enters the conditional block if the argument is true non zero in IF ENDIF or IF ELSE ENDIF REPEAT marks the end of a loop SUB name defines a subroutine name WHILE 1 jumps to the end of a loop if the argument is false zero Control commands command stack effect description Timing commands command stack effect delays by the given number of milliseconds gets the current millisecond timer wraps around from 32767 to 32768 6 The Maestro Scripting Language Page 53 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Stack commands command aa description DEPTH gets the number of numbers on the stack DROP 1 removes the top number from the stack DUP duplicates the top number OVER 1 duplicates the number directly below the top copying it onto the t
22. the argument is true non zero Mathematical commands binary These commands take two arguments from the top of the stack then return a single value as a result The order of the arguments when important is the standard one in mathematics for example to compute 2 you write 1 2 MINUS These commands all have equivalents in C and most other languages listed in the C equivalent column below 6 The Maestro Scripting Language Page 54 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation command C equivalent BITWISE AND applies the boolean AND function to corresponding bits of the arguments BITWISE OR BITWISE XOR applies the boolean OR function to corresponding bits of the arguments applies the boolean XOR function to corresponding bits of the arguments DIVIDE EQUALS divides the arguments true if and only if the arguments are equal GREATER THAN LESS_THAN true if and only if the first argument is greater than the second true if and only if the first argument is less than the second LOGICAL AND LOGICAL OR true if and only if both arguments are true true if and only if at least one argument is true selects the greater of the two arguments selects the lesser of the two arguments MINUS NOT_EQUALS subtracts the arguments computes the remainder on division of the first argument by the second true if and only if the argument
23. the green LED double blinking and the Maestro s bootloader should be visible in your Device Manager if you are using Windows Then you can stop shorting together the pads and retry the firmware upgrade procedure in Section 4 f starting at step 7 4 Using the Maestro Control Center Page 34 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 5 Serial Interface 5 a Serial Settings The Maestro has three different serial interfaces First it has the TX and RX lines which allow the Maestro to send and receive non inverted TTL 0 5 V serial bytes Section 5 b Secondly the Maestro shows up as two virtual serial ports on a computer if it is connected via USB One of these ports is called the Command Port and the other is called the TTL port e In Windows you can determine the COM port numbers of these ports by looking in your computer s Device Manager In Linux the Command Port will usually be dev ttyacmo and the TTL Port will usually be dev ttyAcm1 These numbers may be different on your computer depending on how many serial devices are active when you plug in the Maestro e In Mac OS X 10 7 Lion and later the Maestro s two virtual serial ports will have a name of the form dev cu usbmodem lt number gt for example dev cu usbmodem00654321 The one with the lower number is the Command Port This section explains the serial interface configurations options available in the Serial Se
24. to the Maestro the green LED will flicker constantly The red error user LED usually indicates an error The red LED turns on when an error occurs and turns off when the error flags have been cleared See Section 4 b for more information about errors The red LED can also 1 Overview Page 12 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation be controlled by the user script the red LED will be on if there is an error or if the script command for turning it on was run e The yellow status LED indicates the control status When the Maestro is in auto baud detect mode the default and has not yet detected the baud rate the yellow LED will blink slowly During this time the Maestro does not transmit any servo pulses Once the Maestro is ready to drive servos the yellow LED will periodically flash briefly The frequency of the flashes is proportional to the servo period the amount of time between pulses on a single channel with a period of 20 ms the flashing occurs approximately once per second The number of flashes indicates the state a single flash indicates that none of the servos are enabled no pulses are being sent and all output channels are low while a double flash indicates that at least one of the servos is enabled or one of the output channels is being driven high Also when a valid serial command is received the yellow LED will emit a brief dim flash which ends when the next valid serial co
25. values on the stack Commands always act on the topmost values of the stack and leave their results on the top of the stack The simplest kind of commands are literals numerical values that are placed directly onto the stack For example the program 10 20 35 0 puts the values 10 20 35 and 0 sequentially onto the stack so that it looks like this value 3 0 2 35 1 20 0 10 A more complicated command is the PLUS command which adds the top two numbers leaving the result on the top of the stack Suppose the numbers 1 2 4 and 7 are sequentially placed on the stack and the PLUS command is run The following table shows the result before after 3 7i 2 4 11 1 2 2 0 1 1 Note that the PLUS command always decreases the size of the stack by one It is up to you to make sure that you have enough values on the stack to complete the commands you want to run Consider a more complicated example suppose we want to compute the value of 1 3 x 4 using the MINUS and MULTIPLY commands The way to write this computation as a script is 1 3 MINUS 4 TIMES Comments case whitespace and line breaks All parts of the Maestro script language are case insensitive and you may use any kind of whitespace spaces tabs and newlines to separate commands Comments are indicated by the pound sign everything from the to the end of the line will be ignored by the compiler For example the computation above may be writt
26. 0 us s Mini Maestro 12 18 and 24 only If you use a period other than the default 20 ms the units of speed are different See below for more information Acceleration This option specifies the acceleration of the servo in units of 0 25 us 10 ms 80 ms For example with an acceleration of 4 the speed of the servo will change by a maximum of 1250 s s every second Mini Maestro 12 18 and 24 only If you use a period other than the default 20 ms the units of acceleration are different See below for more information 8 bit neutral This option specifies the target value in microseconds that corresponds to 127 neutral for 8 bit commands 8 bit range This option specifies the range of target values accesible with 8 bit commands An 8 bit value of 0 results in a target of neutral range while an 8 bit value of 254 results in a target value of neutral range Advanced pulse control options are available Period is an advanced option that sets the period of all of the servo pulses in milliseconds This is the amount of time between successive pulses on a given channel If you are unsure about this option leave it at the default of 20 ms Mini Maestro 12 18 and 24 only the units of speed and acceleration depend on the pulse rate The units depend only on Period not on Period multiplier Please refer to the following table for the relationship between Period and speed acceleration units 4 Using the Maestro Control Cente
27. 2014 Pololu Corporation 14 It will take a few seconds to erase the Maestro s existing firmware and load the new firmware Do not disconnect the Maestro during the upgrade 15 Once the upgrade is complete the Firmware Upgrade window will close the Maestro will disconnect from your computer and it will reappear If there is only one Maestro plugged in to your computer the Maestro Control Center will connect to it Check the firmware version number and make sure that it now indicates the latest version of the firmware If you have problems during or after the firmware upgrade then it is possible that you loaded the wrong firmware onto your Maestro or some other problem corrupted the firmware The solution is to retry the firmware upgrade procedure above Even if your Maestro is not recognized at all by your computer and you see no sign of life from it the instructions in step 6 and Section 4 f 1 can help you get the Maestro into bootloader mode If you continue to have trouble after trying multiple times please email us http www pololu com contact for assistance 4 f 1 Hard Bootloader Reset The instructions below describe how to force the Maestro into bootloader mode by performing a hard bootloader reset Most customers do not need to use these instructions but they can be used as a last resort in case something has gone wrong One reason to do a hard bootloader reset is if you accidentally loaded the wrong firmware onto your Mae
28. Maestro 12 18 and 24 support having an unlimited number of subroutines but the subroutines defined after the first 128 can not be started from a serial or native USB command and each call requires 3 bytes of script space 6 The Maestro Scripting Language Page 64 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 7 Wiring Examples This section contains example wiring configurations for the Maestro that demonstrate the different ways it can be connected to your project Although many of the pictures only show the Micro Maestro the information in this section applies to all Maestros unless otherwise noted 7 a Powering the Maestro There are several ways to power your Maestro s processor and the servos it is controlling USB power If you connect a power supply to the servo power terminal and connect the Maestro to USB as shown in the picture to the right then the Maestro s processor will be powered from USB while the servos are powered from the power supply The power supply must output a voltage within the servos respective a Ss operating ranges and must be capable of supplying all the ss current that the servos will draw In this configuration if the computer or other USB host that the Maestro is connected to goes to sleep then by default the Maestro will go to sleep and stop sending servo pulses If you The Micro Maestro s processor can be need to drive your servos whil
29. Mini Maestros Script call stack error bit 7 This error occurs when a bug in the user script has caused the call stack to overflow or underflow An overflow can occur if there are too many levels of nested subroutines or a subroutine calls itself too many times The call stack depth is 10 on the Micro Maestro and 126 on the Mini Maestros An underflow can occur when there is a return without a corresponding subroutine call An underflow will occur if you run a subroutine using the Restart Script at Subroutine serial command and the subroutine terminates with a return command rather than a quit command or an infinite loop Script program counter error bit 8 This error occurs when a bug in the user script has caused the program counter the address of the next instruction to be executed to go out of bounds This can happen if your program is not terminated by a quit return or infinite loop Performance Flags The errors tab also shows which performance flags have been set This feature only applies to the Mini Maestro 12 18 and 24 The performance flags indicate that the processor missed a deadline for performing a servo control task and as a result the Maestro s servo control got slowed down in some way Performance flags should not occur during normal operation as long as your settings are within with the limitations described in Section 9 4 Using the Maestro Control Center Page 25 of 73 Pololu Maestro Servo Control
30. Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation Pololu Maestro Servo Controller User s Guide http www pololu com docs 0J40 all Page of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Te OVERVIEW ie She eR GR An A a a At ne ee tae aa 3 l a Micro Maestro Pinout and Components ooa 7 1 b Mini Maestro Pinout and Components 9 Lc Indicator LEDSA arts e el itt ts died athletics tet Ue he IO tN be Ae Nadas da das 12 1 d Supported Operating Systems 2 i e aE i p E U AEE p i T E E E 13 2 Contacting Pool be ae eee ek lee ed em nee i Pa e ht a a 14 3 Gettne Started o 640 Se oe bh eek kOe eh et 4h SS AR Ee A 15 3 a Installing Windows Drivers and Software ee 15 3 b Installing Linux Drivers and Software ee 20 3 c Using the Maestro without USB 2 2 ee 20 4 Using the Maestro Control Center 22 4 a Status and Real time Control 2 ee 22 ADS BIDEN a Shek ee a me ee a CA AN TNG 24 ALC DO CQUCHICEL esha Mens od ete oa adits Deedee E Sng aa ode adele cate tae dale eb eed BAL aie Bak gd 26 4 d Ent ermeascript 6 Ga thee ho A ESS ae Ge he Be hee tt e 28 4 e Channel Settings as Ate Ae tM TE Ol As th dg OE t A a A OM TA 29 4f Upsrading Firmware s 2 408 A ee eS eR SEED MOE BE eee 31 Af Hard Bootloader Reset paie iga da Sec eg Be eee 33 S Serial Interface pi eA AS A Se ee A 35 Sas O CHAN SCtIN GS 540 A A Te A abs ite te tac
31. SB of your CRC 7 is aligned under a 0 do nothing 5 Shift your CRC 7 right one bit If all 8 bits of your CRC 7 polynomial still line up underneath message bits go back to step 4 6 What s left of your message is now your CRC 7 result transmit these seven bits as your CRC byte when talking to the Maestro with CRC enabled If you have never encountered CRCs before this probably sounds a lot more complicated than it really is The following example shows that the CRC 7 calculation is not that difficult For the example we will use a two byte sequence 0x83 0x01 Steps 1 amp 2 write as binary add 7 zeros to the end of th CRC 7 Polynomial 1 0 0 message 11000001 Steps 3 4 amp 5 least significant bit e message 0100 1 1000000 0 0 first 000000 1000100131100 XOR 1000 0001 000000 001 a a a a a a a at a a E a 0 0 000 000100 1000000 000 0 0 100 0 0 0 1000 0 0 0 0 0 000 0 0 00000000 5 Serial Interface Page 40 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 10100010 10001001 10101100 1000100 10010 00 1000 0 0 1 0 0 0 0x17 So the full command packet we would send with CRC enabled is 0x83 0x01 0x17 5 e Serial Servo Commands The Maestro has several serial commands for setting the target of a ch
32. This firmware version fixes a problem where in some cases the position of a servo with an acceleration limit would never settle to the target value This update also fixes some minor problems with error handling For the Mini Maestros this update also fixes the yellow LED to blink the same way that it does on the Micro Maestro We are not yet shipping Maestros with firmware version 1 02 but it is available for download below 4 Using the Maestro Control Center Page 31 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Upgrade Instructions You can determine the version of your Maestro s firmware by running the Maestro Control Center connecting to a Maestro and looking at the firmware version number which is displayed in the upper left corner next to the Connected to drop down box If you do not already have the latest version 1 02 you can upgrade by following the instructions below 1 Save the settings stored on your Maestro using the Save settings file option in the File menu All of your settings will be reset to default values during the firmware upgrade 2 Determine which type of Maestro you have either by counting the number of channels or by looking at the name that appears in your Device Manager There are four types of Maestro the Micro Maestro 6 Channel USB Servo Controller usc02a the Mini Maestro 12 Channel USB Servo Controller usc03a the Mini Maestro 18 Channel USB Servo
33. USB LED GND VIN 5 16V board power RX TTL serial input TX TTL serial output RST board reset ERR error output TXIN daisy chain input red status LED yellow status LED VSRV VIN jumper Mini Maestro 12 channel USB servo controller fully assembled labeled top view channel 0 channel 1 channel 2 channel 3 channel 4 channel 5 channel 6 channel 7 channel 8 channel 9 channel 10 channel 11 servo power VSRV 1 Overview Page 9 of 73 Pololu Maestro Servo Controller User s Guide USB mini B channel 0 a channel 1 green USB LED channel 2 channel 3 SND channel 4 VIN 5 16V board power channels RX TTL serial input TX TTL serial output ri RST board reset chinna ERR error output channel 6 TXIN daisy chain input innit channel 10 red status LED awe yellow status LED channel servo power VSRV VIN jumper servo power VSRV 2 gt pS Mini Maestro 18 channel USB servo controller fully assembled labeled top view 2 di N Ep yo ooog E d bh ona signal USB mini B a channel 0 comacior channel 1 green USB LED channel 2 GND channel 3 channel 4 VIN 5 16V board power J channel 5 RX TTL serial input TX TTL serial output RST board reset ERR error output TXIN daisy chain input channel 6 channel 7 channel 8 I gt channel 9 E tats lt channel 10 yellow status LED channel 11 VSRV VIN jumper cha
34. Windows COM6 also works const char device dev ttyACM0O Linux 5 Serial Interface Page 47 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation const char device dev cu usbmodem00034567 Mac OS X int fd open device O_RDWR O_NOCTTY if fd 1 perror device return 1 ifndef _WIN32 struct termios options tcgetattr fd amp options options c_lflag amp ECHO ECHONL ICANON ISIG IEXTEN options c_oflag amp ONLCR OCRNL tcsetattr fd TCSANOW amp options endif int position maestroGetPosition fd 0 printf Current position is d n position int target position lt 6000 7000 5000 printf Setting target to d d us n target target 4 maestroSetTarget fd 0 target close fd return 0 5 h 2 Windows C For example C code that shows how to control the Maestro using its serial interface in Microsoft Windows download MaestroSerialExampleC Windows zip http www pololu com file download MaestroSerialExampleC Windows zip file_id 0J545 4k zip This zip archive contains a Microsoft Visual C 2010 Express project that shows how to send a Set Target command and also a Get Position command It can also be compiled with MinGW The Maestro s serial mode needs to be set to USB Dual Port for this code to work This example is like the previous example except it does the serial
35. a A Ao 72 Page 2 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 1 Overview The Maestros are Pololu s second generation family of USB servo controllers The Maestro family consists of four controllers each available fully assembled or as a partial kit e Micro Maestro 6 http www pololu com product 1350 Mini Maestro 12 http www pololu com product 1352 Mini Maestro 18 http www pololu com product 1354 Mini Maestro 24 http www pololu com product 1356 With three control methods USB for direct connection to a PC computer TTL serial for use with embedded systems and internal scripting for self contained host controller free applications and channels that can be configured as servo outputs for use with radio control RC servos http www pololu com category 23 re servos OF electronic speed controls ESCs digital outputs or analog digital inputs the Maestro is a highly versatile servo controller and general I O board in a highly compact package The extremely precise high resolution servo pulses have a jitter of less than 200 ns making the Maestro well suited for high performance animatronics and built in speed and acceleration control make it easy to achieve smooth seamless movements without requiring the control source to constantly compute and stream intermediate position updates to the Maestro The Maestro features configurable pulse rates up to 333 Hz fo
36. annel getting its current position and setting its speed and acceleration limits Set Target Pololu Compact protocol Compact protocol 0x84 channel number target low bits target high bits Pololu protocol 0xAA device number 0x04 channel number target low bits target high bits The lower 7 bits of the third data byte represent bits 0 6 of the target the lower 7 bits while the lower 7 bits of the fourth data byte represent bits 7 13 of the target The target is a non negative integer If the channel is configured as a servo then the target represents the pulse width to transmit in units of quarter microseconds A target value of 0 tells the Maestro to stop sending pulses to the servo If the channel is configured as a digital output values less than 6000 tell the Maestro to drive the line low while values of 6000 or greater tell the Maestro to drive the line high For example if channel 2 is configured as a servo and you want to set its target to 1500 us 1500x4 6000 01011101110000 in binary you could send the following byte sequence in binary 10000100 00000010 01110000 00101110 in hex 0x84 0x02 0x70 0x2E in decimal 132 2 112 46 Here is some example C code that will generate the correct serial bytes given an integer channel that holds the channel number an integer target that holds the desired target in units of quarter microseconds if this is a servo channel and an array called serialByte
37. athode of the LED to GND any ground pad on the Maestro will suffice because they are all connected Then connect the anode of the LED to the channel s signal line through a resistor is needed The signal line has a 220 ohm resistor for protection which means you can connect most LEDs directly to the signal line However you should read your LED s datasheet to make sure and add your own resistor if needed resistor only needed if built in 2200 is not enough Diagram for connecting an LED to the Micro Maestro servo controller You can test your LED by setting the target of the LED channel in the Status tab of the Maestro Control Center The LED should be on if you set the target to be greater than or equal to 1500 us and off otherwise You can control the LED in your script using the SERVO command or over serial using the Set Target command These commands take arguments in units of quarter microseconds so the LED should be on if you send a number greater than or equal to 6000 and off otherwise 3 The total current you can safely draw from the signal lines is limited See Section 1 a and Section 1 b for more information 7 c Connecting to a Microcontroller The Maestro can accept TTL serial commands from a Maestro microcontroller To connect the microcontroller to the Maestro you should first connect the ground line of the microcontroller to the ground line of the Maestro Then connect the TX serial transmit lin
38. bits are set Mini Maestro 12 18 and 24 only enables the PWM output channel with the period specified by the top element and the on time specified by the second element both in units of 1 48 us see Section 4 a for more information about PWM PWM 2 Mini Maestro 12 18 and 24 only removes the top number from the stack cd E interprets it as a single byte and sends that byte to the TTL serial output TX 6 c Example Scripts Getting started blinking an LED The following script will cause the red LED on the Maestro to blink once per second Blinks the red LED once per second begin led_on 100 delay led off 900 delay repeat It is a good idea to try stepping through this script before doing anything further with scripts on the Maestro In particular pay attention to how the command 100 puts the number 100 on the stack and the DELAY command consumes that number In the Maestro scripting language arguments to commands always need to be placed on the stack before the commands that use them which makes the language seem backwards compared to other languages It also means that you can arrange your code in a variety of different ways For example this program is equivalent to the one above Blinks the red LED once per second begin 900 100 6 The Maestro Scripting Language Page 56 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation led_on delay led_off delay repeat
39. bove to wait for a button press including a small delay to eliminate noise or bounces on the input sub wait_for button press wait for button open 10ms wait for button closed 10ms return Wait for the button to be NOT pressed for at least 10 ms sub wait for button open 10ms get ms put the current time on the stack begin reset the time on the stack if it is pressed button EE drop get_ms else get ms over minus 10 greater than if drop return endif endif repeat Wait for the button to be pressed for at least 10 ms sub wait for button closed 10ms get_ms begin reset the time on the stack if it is not pressed button 1f get ms over minus 10 greater than if drop return endif else drop get ms endif repeat An example of how to use wait_for button press is shown below Uses WAIT FOR BUTTON_PRESS to allow a user to step through a sequence of positions on servo 1 main_loop begin 4000 frame 5000 frame 6000 frame 7000 frame 8000 frame repeat sub frame wait for button press 1 servo m return Just like the sequencing examples above the script steps through a sequence of frames but instead of a timed delay between frames this example waits for a button press The WAIT_FOR_BUTTON_PRESS subroutine can be used in a variety of different scripts whenever you want to wait for a button press You could also expand this example to allow multiple buttons continuous motion or a variety of
40. ce must have its most significant bit cleared Therefore the command packet is Y OxAA device number byte command byte with MSB cleared any necessary data bytes For example if we want to set the target of servo 0 to 1500 us for a Maestro with device number 12 we could send the following byte sequence in hex OxAA 0x0C 0x04 0x00 0x70 0x2E in decimal 170 12 4 0 112 46 Note that 0x04 is the command 0x84 with its most significant bit cleared Mini SSC Protocol The Maestro also responds to the protocol used by the Mini SSC servo controller This protocol allows you to control up to 254 different servos by chaining multiple servo controllers together It only takes three serial bytes to set the target of one servo so this protocol is good if you need to send many commands rapidly The Mini SSC protocol is to transmit OxFF 255 in decimal as the first command byte followed by a servo number byte and then the 8 bit servo target byte Therefore the command packet is Y OxFF servo number byte servo target byte For example if we wanted to set the target of servo 0 to its configurable neutral position we could send the following byte sequence in hex OxFF 0x00 0x7F in decimal 255 0 127 The Maestro can be configured to respond to any contiguous block of Mini SSC servo numbers from 0 to 254 The Maestro identifies the Pololu Compact and Mini SSC protocols on the fly you do not need to use a configurati
41. ch device is properly powered Unpowered devices with a TTL serial port can turn on or partially on drawing power from the serial line which means that extra care must be taken when turning power off and on to reset the devices 5 0 Command Protocols You can control the Maestro by issuing serial commands If your Maestro s serial mode is UART detect baud rate you must first send it the baud rate indication byte OXAA on the RX line before sending any commands The OxAA baud rate indication byte can be the first byte of a Pololu protocol command The Maestro serial command protocol is similar to that of other Pololu products Communication is achieved by sending command packets consisting of a single command byte followed by any data bytes that command requires Command bytes always have their most significant bits set 128 255 or Ox80 OxFF in hex while data bytes always have their most significant bits cleared 0 127 or 0x00 0x7F in hex This means that each data byte can only transmit seven bits of information The only exception to this is the Mini SSC command where the data bytes can have any value from 0 to 254 The Maestro responds to three sub protocols Compact Protocol This is the simpler and more compact of the two protocols it is the protocol you should use if your Maestro is the only device connected to your serial line The Maestro compact protocol command packet is simply 9 command byte with MSB set an
42. communication using Windows specific functions like CreateFile and SetCommState See the comments in the source code for more details 5 h 3 PIC18F4550 The following example code for the PIC18F4550 was submitted to us by customer Ney Palma Castillo It is intended to be compiled with the PIC MCU C Compiler http www ccsinfo com content php page compilers The code shows how to control a Maestro via serial commands using pins C6 and C7 It first commands the channel 0 servo to go to its minimum position and then one second later to go to its neutral position Please see Section 5 e for information on connecting the PIC to the Maestro and set the Maestro s serial mode to UART detect baud rate include lt 18f 4550 H gt fuses HSPLL NOMCLR PUT BROWNOUT BORV43 NOWDT NOPROTECT NOLVP fuses NODEBUG USBDIV PLL5 CPUDIV1 VREGEN CCP2B3 use delay clock 48000000 define TTL _TX1 PIN_C6 define TTL _RX1 PIN C7 use rs232 xmit TTL_TX1 rcv TTL_RX1 bits 8 parity N void main delay _ms 2000 while true Send a Set Target command using the Pololu protocol putc 0xAA Start Byte putc 0x0C Device ID 12 putc 0x04 Command Set Target putc 0x00 Channel 0 putc 0x20 Target position 1000 us typical minimum for servos putc 0x1F delay ms 1000 Send another Set Target command using the Pololu protocol 5 Serial Interface Page 48 of 73 Pololu Maestro Servo Cont
43. configuration For example using the Pololu protocol at 115 2 kbps sending the Set Multiple Targets command lets you set the targets of 24 servos in 4 6 ms while sending 24 individual Set Target commands would take 12 5 ms Set Speed Compact protocol 0x87 channel number speed low bits speed high bits Pololu protocol 0xAA device number 0x07 channel number speed low bits speed high bits This command limits the speed at which a servo channel s output value changes The speed limit is given in units of 0 25 us 10 ms except in special cases see Section 4 e For example the command 0x87 0x05 0x0C 0x01 sets the speed of servo channel 5 to a value of 140 which corresponds to a speed of 3 5 us ms What this means is that if you send a Set Target command to adjust the target from say 1000 us to 1350 ps it will take 100 ms to make that adjustment A speed of 0 makes the speed unlimited so that setting the target will immediately affect the position Note that the actual speed at which your servo moves is also limited by the design of the servo itself the supply voltage and mechanical loads this parameter will not help your servo go faster than what it is physically capable of At the minimum speed setting of 1 the servo output takes 40 seconds to move from to 2 ms The speed setting has no effect on channels configured as inputs or digital outputs Set Acceleration Compact protocol 0x89 channel number acceleration low bit
44. cript on startup Script 63 of 8192 bytes used Subroutines 0 of 126 levels used 1 A simple sequence of servo movements with a 2 speed that depends on the analog voltage input value of channel 5 begin Beginning of loop 4555 4574 frame Add servo targets to stack and run frame 7784 7765 frame 5240 5220 frame 7001 5220 frame 5142 7001 frame 6943 5201 frame 5435 6845 frame repeat Go back to beginning of loop sub frame 1 servo O servo Set servos 0 4 1 using the top 2 stack values 5 ae Get the analog voltage of channel 5 0 1023 delay Delay by that number of milliseconds return b soson E EEE Fosaa 6 soottotaow era en Conte Gate 4 O MN UY hb mn 00 Save Frame 7 The Script tab in the Maestro Control Center The Script tab is where you enter a script to be loaded into the Maestro For details on the Maestro scripting language see Section 6 Once you have entered a script and clicked the Apply Settings button to load the script on to the device there are a number of options available for testing and debugging your script on the Script tab Running and stepping through a script To start a script running click the green button labeled Run Script Your script will be processed by the Maestro one instruction at a time until a QUIT instruction is reached or an error occurs In many cases it will be useful to use a loop of some kind to cause a script to
45. d 254 0 mini_ssc set servo 0 to position 254 repeat sub mini_ssc OxFF serial send byte serial send byte serial send byte return 6 d Script Specifications The user scripting language available on the Mini Maestros is more powerful than that available on the Micro Maestro The differences are summarized in the table below Micro Maestro Mini Maestro 12 18 and 24 Script size 1KB 8 KB Stack size 32 126 Call stack size 10 126 Number of subroutines 128 unlimited Extra commands PEEK POKE PWM SERIAL SEND BYTE Script size This is the number of bytes of persistent memory that can be used to store your code A bigger script size allows you to store more servo motion frames and to write more complex programs Stack size This is the maximum number of values that can be on the stack at the same time A bigger stack allows you to have more variables do bigger computations and worry less about whether the stack will overflow Call stack size This is the maximum subroutine nesting depth the maximum number of subroutines that can be called without returning Number of subroutines This is the number of different subroutines you are allowed to have The first 128 subroutines defined in your script are special these subroutines can be started using a serial or native USB command and each call from within your script requires only one byte of script space The Micro Maestro only supports having up to 128 subroutines The Mini
46. d the virtual serial port The native USB interface provides more features than the serial port such as the ability to change configuration parameters and select the Maestro by its serial number Also the USB interface allows you to recover more easily from temporary disconnections The virtual serial port interface is easier to use if you are not familiar with programming and it can work with existing software programs that use serial ports such as LabView Native USB Interface The Pololu USB Software Development Kit http www pololu com docs 0341 supports Windows and Linux and includes the source code for Cuneo _Qumie Temet i000 MaestroLasyExampie n Visual Bas s Maestrotasyixemple in C8 e MaestroEasyExample a _ simple example application that uses native USB and has three buttons The Pololu USB SDK contains example code for that control the Maestro Versions of this example are the Maestro in C Visual C and Visual Basic available in CH Visual Basic NET and Visual C NET e MaestroAdvancedExample an example graphical application that uses native USB to send commands and receive feedback from the Maestro and automatically recover from disconnection written in C e UseCmd a command line utility for configuring and controlling the Maestro written in CF e C NET class libraries that enable native USB communication with the Maestro written in C You can modify the applications in the SDK to suit your nee
47. depth while 100 times 0 servo 100 delay repeat return In this version of the code we have rewritten the FRAME subroutine using the DEPTH command to automatically load frames from the stack until there are none left This program uses 34 bytes to store 31 frames for an average of 6 The Maestro Scripting Language Page 58 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation just 1 1 bytes per frame We could store a sequence containing 900 different positions in the memory of the Micro Maestro using this kind of script Making smooth sequences with GET MOVING STATE Speed and acceleration settings can be used to make smooth motion sequences with the Maestro However a common problem is that you do not know how much you need to delay between frames to allow the servo to reach its final position Here is an example of how to use the built in function GET _MOVING_STATE to make a smooth sequence instead of DELAY This example uses speed and acceleration to make a smooth motion back and forth between 1 and 2 ms 3 0 acceleration 30 0 speed begin 4000 0 servo set servo 0 to 1 00 ms moving wait 8000 0 servo 2 00 ms moving _wait repeat sub moving wait begin get moving state while E wait until it is no longer moving repeat return GET_MOVING_STATE returns a l as long as there is at least one servo that is limited by a speed or acceleration setting still moving so you can use it whene
48. ds or you can use the class libraries to integrate the Maestro in to your own applications Example code that uses the native USB interface from other languages can be found in Section 10 Virtual Serial Ports Almost any programming language is capable of accessing the COM ports created by the Maestro We recommend the Microsoft NET framework which is free to use and contains a SerialPort class that makes it easy to read and write bytes from a serial port You can download Visual Studio Express for either C C or Visual Basic and write programs that use the SerialPort class to communicate with the Maestro You will need to set the Maestro s serial mode to be either USB Dual Port or USB Chained The serial interface is documented in Section 5 For example serial code in many different languages see Section 5 h and Section 10 8 Writing PC Software to Control the Maestro Page 69 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 9 Maestro Settings Limitations Mini Maestro serial baud rate limitations On the Mini Maestro 12 18 and 24 the following baud rates should not be exceeded or the processor may become overloaded causing degraded performance 10 100 Hz 111 250 Hz 333 Hz Serial mode UART USB chained 200 kbps 115 2 kbps 115 2 kbps Serial mode Dual port 115 2 kbps 57 6 kbps 57 6 kbps Assuming bytes are not sent and received simultaneously as required for the
49. dundancy check CRC byte at the end of every serial command except the Mini SSC command see Section 5 d Device Number This is the device number 0 127 that is used to address this device in Pololu Protocol commands This setting is useful when using the Maestro with other devices in a daisy chained configuration see Section 5 g 5 Serial Interface Page 36 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Mini SSC offset This parameter determines which servo numbers the device will respond to in the Mini SSC protocol see Section 5 e Timeout This parameter specifies the duration before which a Serial timeout error will occur This error can be used as a safety measure to ensure that your servos and digital outputs go back to their default states whenever the software sending commands to the Maestro stops working The serial timeout error will occur whenever no valid serial commands or qualifying native USB commands are received within the specified timeout period A timeout period of 0 00 disables the serial timeout error The resolution of this parameter is 0 01 s and the maximum value available is 655 35 s The native USB commands that qualify correspond to the following methods in the Usc class setTarget setSpeed setAcceleration setPwm disablePWM and clearErrors Running the Maestro Control Center will not prevent the serial timeout error from occurring but setting targets in the Status tab
50. e from RX has been lost as a result This error should not occur during normal operation 4 Using the Maestro Control Center Page 24 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Serial CRC error bit 3 This error occurs when the Maestro is running in CRC enabled mode and the cyclic redundancy check CRC byte at the end of the command packet does not match what the Maestro has computed as that packet s CRC Section 5 d In such a case the Maestro ignores the command packet and generates a CRC error Serial protocol error bit 4 This error occurs when the Maestro receives an incorrectly formatted or nonsensical command packet For example if the command byte does not match a known command or an unfinished command packet is interrupted by another command packet this error occurs Serial timeout error bit 5 When the serial timeout is enabled this error occurs whenever the timeout period has elapsed without the Maestro receiving any valid serial commands This timeout error can be used to make the servos return to their home positions in the event that serial communication between the Maestro and its controller is disrupted Script stack error bit 6 This error occurs when a bug in the user script has caused the stack to overflow or underflow Any script command that modifies the stack has the potential to cause this error The stack depth is 32 on the Micro Maestro and 126 on the
51. e bottom of the board between VIN and one of the servo f S y power connections as shown in the picture to the right Only one ground AS Pololu connection is needed because all ground pins on the board are connected a Engage 2009 www pololu com The 5V out power output allows you to power your own 5V devices from y qu e the on board 50mA regulator or directly from USB The on board regulator is used whenever VIN is powered in this case since the Maestro requires Micro Maestro configured to use 30 mA there is about 20 mA available to power other devices a single power supply for both board and servos The SIG lines 0 1 2 are used for sending pulses to servos controlling digital outputs and measuring analog voltages These lines are protected by 2204 resistors The total current limit in or out for these pins is 60 mA but when using the on board regulator the current out is limited to 20 mA see above The RX line is used to receive non inverted TTL 0 5 V serial bytes such as those from microcontroller UARTs These bytes can either be serial commands for the Maestro arbitrary bytes to send back to the computer via the USB connection or both For more information about the Maestro s serial interface see Section 5 a Note that the Maestro will probably be able to receive 3 3V TTL serial bytes but it is not guaranteed to read 3 3V as high on the RX pin so you should boost 3 3V TTL serial signals to above 4V 1
52. e number for a particular subroutine click the View Compiled Code button and look at the list below Subroutines used this way should not end with the RETURN command since there is no place to return to instead they should contain infinite loops or end with a QUIT command 5 Serial Interface Page 44 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Restart Script at Subroutine with Parameter Compact protocol 0xA8 subroutine number parameter low bits parameter high bits Pololu protocol 0xAA device number 0x28 subroutine number parameter low bits parameter high bits This command is just like the Restart Script at Subroutine command except it loads a parameter on to the stack before starting the subroutine Since data bytes can only contain 7 bits of data the parameter must be between 0 and 16383 Get Script Status Compact protocol 0xAE Pololu protocol 0xAA device number 0x2E Response 0x00 if the script is running 0x01 if the script is stopped This command responds with a single byte either 0 or 1 to indicate whether the script is running 0 or stopped 1 Using this command together with the commands above you can activate a sequence stored on the Maestro and wait until the sequence is complete before moving on to the next step of your program 5 g Daisy Chaining This section is a guide to integrating the Maestro in to a project that has multiple TTL serial device
53. e of the microcontroller to the RX line of the Maestro so that the microcontroller can send commands If you need to receive serial responses from the Maestro then you will need to connect the RX serial receive line of the microcontroller to the Maestro s TX line For more information on the different serial modes and commands see Section 5 optional If you want your microcontroller to have the ability to reset the Diagram showing how to connect the Maestro then connect the RST line of the Maestro to any general Micro Maestro servo controller to a purpose I O line of the microcontroller You should have the I O line microcontroller tri stated or at 5 V when you want the Maestro to run and drive it low 0 V temporarily to reset the Maestro If you want your microcontroller to have the ability to detect errors from the Maestro using a digital input instead of the serial command or you want to receive direct feedback from the user script then connect the ERR line of the Maestro to any general purpose I O line of the microcontroller The ERR line is only available on the Mini Maestro 12 18 and 24 channel servo controllers See Section 1 b for more information about the ERR line 7 Wiring Examples Page 68 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 8 Writing PC Software to Control the Maestro There are two ways to write PC software to control the Maestro the native USB interface an
54. e your computer is off you can powered Cae while tHe ern are use the Never sleep ignore USB suspend option in the Serial aa di Settings tab of the Maestro Control Center Note that this will only work if the computer is supplying power to the USB port while it is asleep and it will make your Maestro be non USB compliant Two power supplies If you connect a power supply to the servo power terminal and connect another power supply to GND VIN then the Maestro s processor will be powered from the VIN supply while the servos are powered from their own supply The VIN supply must be within 5 16 V and be capable of supplying at least 30 mA to the GND 0V Micro Maestro or 50 mA to the Mini Maestro The servo power KLE dy supply must output a voltage within the servos respective E ANI operating ranges and must be capable of supplying all the be Se current that the servos will draw oa The Micro Maestro s processor and servos can be powered separately 7 Wiring Examples Page 65 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation One power supply If you connect a single power supply to VIN and the servo power terminal then the Maestro s processor and the servos will be powered from that supply The supply must be within 5 16 V and be within the servos respective operating ranges and must be capable of supplying all the current that the servos will draw GND 0V On the Micro Ma
55. ed a name for your convenience Channel names are not stored on the device but instead in the system registry on your computer if you want to use your Maestro on a different computer without losing the names save a settings file on the old computer and load it into the Maestro with the new one Mode The mode of the channel is the most basic setting determining its operation There are three options e Servo the default indicates an R C servo PWM output Input specifies that the channel should be used as an analog or digital input The inputs on channels 0 11 are analog they are measured continuously as a value between 0 and 1023 VCC at a maximum rate of about 20 kHz The inputs on channels 12 23 are digital their values are either exactly 0 or exactly 1023 Note that the values displayed in the Target and Position boxes in the Status tab are one quarter of the actual input value so 1023 is displayed as 255 75 4 Using the Maestro Control Center Page 29 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation e Output specifies that the channel should be used as a simple digital output Instead of indicating a pulse width the position value of the channel is used to control whether the output is low 0 V or high VCC Specifically the output is low unless the position value is greater than or equal to 1500 00 us Rate specifies the pulse rate for each Servo channel On the Micro Maestro 6 all servos m
56. en as 6 The Maestro Scripting Language Page 50 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 1 3 miNUS 4 this is a comment times with absolutely no effect on the compiled program We generally use lower case for commands and two or four spaces of indentation to indicate control structures and subroutines but feel free to arrange your code to suit your personal style Control structures The Maestro script language has several control structures which allow arbitrarily complicated programs to be written Unlike subroutines there is no limit to the level of nesting of control structures since they are all ultimately based on GOTO commands discussed below and simple branching By far the most useful control structure is the BEGIN REPEAT infinite loop an example of which is given below move servo 1 back and forth with a period of 1 second begin 8000 1 servo 500 delay 4000 1 servo 500 delay repeat This infinite loop will continue forever If you want a loop that is bounded in some way the WHILE keyword is likely to be useful WHILE consumes the top number on the stack and jumps to the end of the loop if and only if it is a zero For example suppose we want to repeat this loop exactly 10 times 10 start with a 10 on the stack begin dup copy the number on the stack the copy will be consumed by WHILE while jump to the end if the count reaches 0 8000 1 servo 500 delay
57. es the selected frame s with the current target values from the Maestro If the Play in a loop checkbox is checked sequence playback will loop back to the beginning of the sequence whenever it reaches the end 4 Using the Maestro Control Center Page 26 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation The Sequence dropdown box along with the Rename Delete and New Sequence buttons allow you to create and manage multiple sequences A sequence can also be used to create a script which is stored on the Maestro There are two buttons for copying the sequence into the script e Copy Sequence to Script sets the script to a looped version of the sequence In most cases you will also want to check the Run script on startup option in the Script tab so that the script runs automatically when the Maestro is powered up enabling fully automatic operation without a connection to a computer e Copy all Sequences to Script is an advanced option that adds a set of subroutines to the end of the current script Each subroutine represents one of the sequences calling the subroutine from the script will cause the sequence to be played back a single time These subroutines must be used together with custom script code for example you could make a display in which a button connected to an input channel triggers a sequence to play back Sequence Editing Tips e You can select multiple frames by holding down the Ct
58. estro 6 channel servo controller one way to do the wiring for this configuration is to add a wire to between the servo power rail and the VIN line Servos On the Mini Maestro 12 18 and 24 channel servo controllers the recommended way to do the wiring for this configuration is to connect your power supply to the dedicated servo power pins Vservo VIN 5 16V in the corner of the board and use the included blue shorting block to connect the pins labeled VSRV VIN The Micro Maestro s processor and servos can be powered from a single 5 16V supply if you connect the positive servo power rail to VIN 7 b Attaching Servos and Peripherals On the Maestro any of the channels can be used as RC servo pulse output as an analog digital input or as a digital output This allows the Maestro to control servos read button presses read potentiometer positions drive LEDs and more The channels can be controlled from the user script within the Maestro or externally over TTL level serial or USB Servo To connect a servo to the Maestro you must first decide which channel you would like to use If the channel is not already configured to be in servo mode the default then in the Maestro Control Center under the Channel Settings tab change that channel to Servo mode and click Apply Settings Connect your servo cable to the channel being careful not to plug it in backwards Make sure to connect your servo correctly or it might be d
59. estroyed The signal usually white orange or yellow wire should be toward the inside of the board and the ground wire usually black or brown should be closest to the edge of the board You will need to connect a DC power supply for your servos See Section 7 a for powering information You can test your servo by setting the target of the servo channel in the Status tab of the Maestro Control Center If you enable the servo channel by checking the Enabled checkbox you should be able to make the servo move by dragging the slider bar left and right Now you can control the servos in your script using the SERVO command or over serial using the Set Target command These commands take arguments in units of quarter microseconds so you should multiply the Target values you see in the Status tab by four to compute correct arguments to these commands More advanced commands are also available for controlling your servos 7 Wiring Examples Page 66 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Button or switch To connect a button or switch to the Maestro you must first decide which channel you would like to use In the Maestro Control Center under the Channel Settings tab change that channel to Input mode and click Apply Settings Next wire a pull up resistor 1 100 kilo ohms between the signal line of that channel and 5 V so that the input is high a p 5 V when the switch is open Wi
60. f you want to ensure reliable operation The TX line transmits non inverted TTL 0 5 V serial bytes These bytes can either be responses to serial commands sent to the Maestro or arbitrary bytes sent from the computer via the USB connection The RST pin can be driven low to reset the Maestro s microcontroller but this should not be necessary for typical applications The line is internally pulled high so it is safe to leave this pin unconnected Driving RST low is roughly equivalent to powering off the Maestro it will not reset any of the configuration parameters stored in non volatile memory To reset the configuration parameters select Device gt Reset to default settings in the Maestro Control Center 1 Overview Page 8 of 73 Pololu Maestro Servo Controller User s Guide OM EK EK EE E e3 es e 5 RST TX RX VIN 069000500 2001 2014 Pololu Corporation 5v tout A a 0 y GND 0 1433 USCIZA EN Pololu Engage 2009 Your Brain www pololu com Micro Maestro 6 channel USB servo controller bottom view with quarter for size reference The dimensions of the Micro Maestro PCB are 1 2 x 0 85 The mounting holes have a diameter of 0 086 and are intended for 2 or M2 screws The vertical and horizontal distances between the two mounting holes are 0 65 and 0 575 The Micro Maestro weighs 3 0 g 0 11 oz without header pins 1 b Mini Maestro Pinout and Components USB mini B connector green
61. finished your start menu should have a shortcut to the Maestro Control Center in the Pololu folder This is a Windows application that allows you to configure control debug and get real time feedback from the Maestro There will also be a command line utility called UscCmd which you can run at a Command Prompt Windows 8 Windows 7 and Windows Vista users Your computer should now automatically install the necessary drivers when you connect a Maestro No further action from you is required Windows XP users Follow steps 5 9 for each new Maestro you connect to your computer 5 Connect the device to your computer s USB port The Maestro shows up as three devices in one so your XP computer will detect all three of those new devices and display the Found New Hardware Wizard three times Each time the Found New Hardware Wizard pops up follow steps 6 9 6 When the Found New Hardware Wizard is displayed select No not this time and click Next 3 Getting Started Page 15 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Found New Hardware Wizard Welcome to the Found New Hardware Wizard Windows will search for current and updated software by looking on your computer on the hardware installation CD or on the Windows Update Web site with your permission Read our privacy policy Can Windows connect to Windows Update to search for software O Yes this
62. he Maestro Control Center Page 22 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation The Speed and Acceleration inputs allow the speed and acceleration of individual servo channels to be adjusted in real time The default values are specified in the Settings tab but it can be useful to adjust them here for fine tuning All of the controls on this tab always display the current values as reported by the Maestro itself so they are useful for monitoring the actions caused by another program or device For example ifa microcontroller uses the TTL serial interface to change the speed of servo channel 2 to a value of 10 this value will be displayed immediately in the corresponding input even if something else was formerly entered there PWM Output Mini Maestro 12 18 and 24 only On the Mini Maestro 12 18 and 24 one of the channels may be used as a general purpose PWM output with a frequency from 2 93 kHz to 12 MHz and up to 10 bits of resolution This could be used for example as an input to a motor driver or for LED brightness control The PWM output is on channel 8 for the Mini Maestro 12 and on channel 12 for the Mini Maestro 18 and 24 This channel FI Peto Maestro Control Center Fe Dexe fet Help Corrected to 00000101 Ae verso 100 Eror code O90000 Sats Emam Chamel Setinga Senai Senings Sequence Sora 23 Serve PWM Ott Y rabia PAN on dume 12 must be configured as an
63. he Mini SSC Offset parameter to different values for each Maestro The Mini SSC Offset is added to the channel number to compute the correct channel address to use with this command For example a Micro Maestro 6 channel servo controller with a Mini SSC Offset of 12 will obey Mini SSC commands whose address is within 12 17 Set Multiple Targets Mini Maestro 12 18 and 24 only Compact protocol 0x9F number of targets first channel number first target low bits first target high bits second target low bits second target high bits Pololu protocol 0xAA device number 0x1F number of targets first channel number first target low bits first target high bits second target low bits second target high bits This command simultaneously sets the targets for a contiguous block of channels The first byte specifies how many channels are in the contiguous block this is the number of target values you will need to send The second byte specifies the lowest channel number in the block The subsequent bytes contain the target values for each of the channels in order by channel number in the same format as the Set Target command above For example to set channel 3 to 0 off and channel 4 to 6000 neutral you would send the following bytes Ox9F 0x02 0x03 0x00 0x00 0x70 0x2E The Set Multiple Targets command allows high speed updates to your Maestro which is especially useful when controlling a large number of servos in a chained
64. id 0J266 SMB zip 2 Open the ZIP archive and run setup exe The installer will guide you through the steps required to install the Maestro Control Center the Maestro command line utility UscCmd and the Maestro drivers on your computer If the installer fails you may have to extract all the files to a temporary directory right click setup exe and select Run as administrator 3 During the installation Windows will ask you if you want to install the drivers Click Install Windows 7 8 and Vista or Continue Anyway Windows XP Would you like to install this device software Software Installation Name Pelolu USE AVR Programmer Drivers Publisher Polelu Comonuton The software you are installing has not passed Windows Logo testing to vesty its compatibuity wath Windows XP Tel me very Ajans trust software focen Poloha Corporation instal Dog install UE Vou should ordy instal driver software from publinhers you trust How can decide ang your installation of this software may impair mitch dence software ade to natal or the correct operation ol your system Would you like to install this device software Name Polotu USB to Senat Orivers y Pobisher Pololu Corporation Aways trust software faon Poloks Corporation instal Don t install Vou should only install driver software from publishers you trust How can decide miech dence software i sate to install 4 After the installation is
65. ifthe E 4 e O VIN 5 16V board voltage external supply falls below 5 V correct operation is not guaranteed Le El 5V regulator output even if USB is also connected oo Servo power connections are provided in the lower right corner of the Mini Maestro board On the Mini Maestro 18 and 24 you can make servo power connections via a 2 pin terminal block or a 2 pin 0 1 header the Mini Maestro 12 only has a 2 pin 0 1 header for connecting servo power Servo power is passed directly to the servos without going through a regulator so the only restrictions on your servo power supply are that 1t must be within the operating range of your servos and provide enough current for your Ada of El GNO groundiov application Please consult the datasheets for your servos to p O VSRV servo voltage determine an appropriate servo power source and note that a ooon een O VIN 5 16V board voltage ballpark figure for the current draw of an average straining servo is O 5V regulator output 1A cuttable trace on bottom You can power the Maestro s processor and servos from a single power supply by connecting the positive power line to both VIN and the servo power ports only one ground connection is needed because all ground pins on the board are connected The recommended way to do this is to connect your power supply to the dedicated servo power pins in the corner of the board and use the included blue shorting b
66. individually addressed and it allows responses to be sent without collisions If the devices are configured to detect the baud rate then when you issue your first Pololu Protocol command the devices can automatically detect the baud from the initial OxAA byte Some older Pololu devices use 0x80 as an initial command byte If you want to chain these together with devices expecting OXAA you should first transmit the byte 0x80 so that these devices can automatically detect the baud rate and only then should you send the byte OxAA so that the Maestro can detect the baud rate Once all devices have 5 Serial Interface Page 46 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation detected the baud rate Pololu devices that expect a leading command byte of 0x80 will ignore command packets that start with OxAA and the Maestro will ignore command packets that start with 0x80 5 h Serial Example Code 5 h 1 Cross platform C The example C code below works on Windows Linux and Mac OS X 10 7 or later It demonstrates how to set the target of a Maestro channel by sending a Set Target command to its Command Port and how to read the position of a channel by sending the Get Position command The Maestro s serial mode needs to be set to USB Dual Port for this code to work You will also need to modify the line that specifies the name of the COM port device 3 This code will work in Windows if compiled with MinGW
67. ining serial devices using the Pololu protocol An optional AND gate is used to join multiple TX lines The Mini Maestro 12 18 and 24 have a special input called TXIN that eliminates the need for an external AND gate the AND gate is built in to the Maestro To make a chain of devices using the TXIN input connect them like this 5 Serial Interface Page 45 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Pololu USB device Serial devices using or microcontroller Pololu protocol o B DNA Nje Daisy chaining serial devices that have a TXIN input Using a PC and a Maestro together as the master device The Maestro can enable a personal computer to be the master device The Maestro must be connected to a PC with a USB cable and configured to be in either USB Dual Port or USB Chained serial mode In USB Dual Port mode the Command Port on the PC is used for sending commands directly to the Maestro and the TTL Port on the PC is used to send commands to all of the slave devices In the USB Chained mode only the Command Port is used on the PC to communicate with the Maestro and all of the slave devices Select the mode that is most convenient for your application or easiest to implement in your programming language Using a Maestro as a slave device The Maestro can act as a slave device when configured to be in the UART serial mode In this mode commands are received on the RX line and responses are se
68. ist you should see an entry for the Maestro 3 Getting Started Page 18 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation gy Device Manager File Action View Help sio Bale D amp P Network adapters a fi Pololu USB Devices 3 H Pololu Micro Maestro 6 Servo Controller a 7 Ports COM amp LPT vy Communications Port COM1 E Pololu Micro Maestro 6 Servo Controller Command Port COM3 ed gt Pololu Micro Maestro 6 Servo Controller TTL Port COM4 gt A Processors Windows 7 device manager showing the Micro Maestro 6 channel USB servo controller Device Manager File Action view Help gt amp g 2 Network Bus Enumerator Pololu USB Devices Pololu Micro Maestro 6 Servo Controller Ports COM amp LPT Pololu Micro Maestro 6 Servo Controller Command Port COM F Pololu Micro Maestro 6 Servo Controller TTL Port COMS SB Processors BABA Soanste Naviac Windows XP device manager showing the Micro Maestro 6 channel USB servo controller Some software will not allow connection to higher COM port numbers If you need to change the COM port number assigned to your USB device you can do so using the Device Manager Bring up the properties dialog for the COM port and click the Advanced button in the Port Settings tab From this dialog you can change the COM port assigned to your device 3 Getting Started Page 19 of 73 Pololu Maestro Servo
69. ler User s Guide 2001 2014 Pololu Corporation 4 c Sequencer Ed Pololu Maestro Control Center File Device Edit Help Connected to Firmware version 1 01 Sequence Fanes E Play in a loop Frame 4 Frame 5 Move Move Frame Down Tip select multiple frames with Ctrl Click or Shift Click The Sequence tab in the Maestro Control Center The Sequence tab allows simple motion sequences to be created and played back on the Maestro A sequence is simply a list of frames specifying the positions of each of the servos and a duration in milliseconds for each frame Sequences are stored in the registry of the computer where the sequence was created Sequences can be copied to the script which is saved on the Maestro Sequences can also be exported to another computer via a saved settings file To begin creating a sequence click the New Sequence button and enter a name for the sequence Using the controls in the Status tab set each of the servos to the position you would like for the first frame then click Save Frame at the bottom of the window Repeat to create several frames then switch back to the Sequence tab You can now play back the sequence using the Play Sequence button or you can set the servos to the positions of the specific frame by clicking the Load Frame button The Frame properties button allows you to set the duration and name of a frame The Save Over Current Frame button overwrit
70. lock to connect the pins labeled VSRV VIN The 5V out power output allows you to power your own 5V devices from the 150mA on board regulator or directly from USB The on board regulator is used whenever VIN is powered in this case since the Maestro requires 50 mA there is about 50 mA N Hea r 1 O VSRV servo voltage available to power other devices PBA O VIN 5 16V board voltage i Oo 5V regulator output The signal lines 0 1 2 are used for sending pulses to servos 4 w cuttable trace on botiom controlling digital outputs and measuring voltages The total current limit in or out for these pins is 150 mA but when using the on board regulator the current out is limited to 50 mA see above Mini Maestro 24 power pins The RX line is used to receive non inverted TTL 0 5 V serial bytes such as those from microcontroller UARTs These bytes can either be serial commands for the Maestro arbitrary bytes to send back to the computer via the USB connection or both For more information about the Maestro s serial interface see Section 5 a Note that the Maestro will probably be able to receive 3 3V TTL serial bytes but it is not guaranteed to read 3 3V as high on the RX pin so you should boost 3 3V TTL serial signals to above 4V if you want to ensure reliable operation The TX line transmits non inverted TTL 0 5 V serial bytes These bytes are either generated by the Mini Maestro itself as respo
71. lu Corporation A USB A to mini B cable http www pololu com product 130 not included is required to connect this device to a computer 1 Overview Page 4 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Features Three control methods USB TTL 5 V serial and internal scripting 0 25us output pulse width resolution corresponds to approximately 0 025 for a typical servo which is beyond what the servo could resolve Configurable pulse rate and wide pulse range see the Maestro comparison table below Individual speed and acceleration control for each channel Channels can be optionally configured to go to a specified position or turn off on startup or error Alternate channel functions allow the channels to be used as o General purpose digital outputs 0 or 5 V o Analog or digital inputs channels 0 11 can be analog inputs channels 12 can be digital inputs o One channel can be a PWM output with frequency from 2 93 kHz to 12 MHz and up to 10 bits of resolution see Section 4 a for details A simple scripting language lets you program the controller to perform complex actions even after its USB and serial connections are removed Linux makes it easy to Free configuration and control application for Windows and gt Configure and test your controller Create run and save sequences of servo movements for animatronics and walking robots o Write step through and
72. lue send 10 bit value send 10 bit value 0 1 8000 1 servo servo toggle the latch pin return sends a numerical value as a sequence of 10 bits sub send 10 bit value 512 OO E begin dup while over over bitwise and send bit 1 shift right 7 7 repeat drop drop return sends a single bit sub send bit if 8000 else 0 endif 2 servo set DATA to 0 or 1 0 0 8000 0 servo servo toggle CLOCK return Note that we use 0 to set the output low and 8000 to set the output high These are reasonable choices but any value from 0 to 5999 could be used for low and anything from 6000 to 32767 could be used for high if desired 6 The Maestro Scripting Language Page 63 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Serial output Mini Maestro 12 18 and 24 only On the Mini Maestro 12 18 and 24 a script can be used to send serial data out on the TTL level serial port TX This means that the Maestro can control additional Maestros allowing for large numbers of channels without a separate microcontroller Here is a simple program that shows how a serial command can be used to control another Maestro To use this code configure both Maestros in UART mode at the same baud rate and connect TX on the master to RX on the slave 100 delay initial delay to make sure that the other maestro has time to initialize begin 127 0 mini_ssc set servo 0 to position 127 using the mini SSC comman
73. m servo scriber software free 4 channel release 10 Related Resources Page 72 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Accessories e Pololu Maestro Case http www thingiverse com thing 6876 This is a 3D design on Thingiverse for a case designed to fit the Micro Maestro 6 channel USB Servo Controller 10 Related Resources Page 73 of 73
74. minimums and maximums for specific channels according to the restrictions given in that row However you do not need to specify the ranges of your servos in advance you can switch some channels off or adjust their positions to access a wider range on other 9 Maestro Settings Limitations Page 70 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation channels If your settings happen to violate these restrictions the servo period might increase and the units of speed and acceleration limits will change accordingly but the operation of the Maestro will not be affected in any other way For example with a Mini Maestro 24 running at 250 Hz a 4 ms period you may use 12 servos with a range of 576 2880 us and 6 servos with a range of 64 2880 us The remaining 6 channels must each be off or have their mode set to Input or Output not Servo Allowed pulse ranges at 333 Hz Allowed pulse ranges at 250 Hz Allowed pulse ranges at 200 Hz Servos Min Max Servos Min Max Servos Min Max 6 64 2328 6 64 3000 6 64 3000 6 192 2648 12 64 2752 12 64 3000 12 64 1752 12 384 3000 6 6 384 64 3000 12 384 2456 6 6 384 64 3000 18 64 3000 6 6 384 64 2072 18 64 2176 12 6 576 64 3000 18 64 1176 18 576 3000 24 64 2600 18 576 2264 12 6 576 64 2880 24 768 3000 24 768 2072 24 64 1600 18 6 768 64 3000 24 768 3000 18 6 768 64 2688
75. mmand is received or when the main blinking occurs whichever happens first Mini Maestros with firmware version 1 00 only emit single flashes unless a servo channel with a speed or acceleration limit is enabled This behavior was fixed in firmware version 1 02 to be consistent with the Micro Maestro When the Maestro is reset in some other way than being initially powered up the red and or yellow LEDs blink four times to indicate the reset condition e Yellow off red blinking A brownout reset This occurs when the Maestro s 5 V line drops below about 3 0 V usually due to low batteries or an inadequate power supply e Yellow blinking red off The Maestro was reset by a low voltage on its RST line e Yellow and red blinking together A firmware crash resulted in a watchdog reset This also occurs immediately following a firmware upgrade as a normal part of the upgrade process e Yellow blinking red steady A firmware error resulted in a soft reset This should never occur during normal usage 1 d Supported Operating Systems The Maestro USB drivers and configuration software work under Microsoft Windows XP Windows Vista Windows 7 Windows 8 and Linux We do not provide any software for Mac OS X but the Maestro s two virtual COM ports are compatible with Mac OS X 10 7 Lion and later The Maestro must be initially configured from a Windows or Linux computer but after that it can be controlled from a Mac 3 Mac OS X co
76. mpatibility we have confirmed that the Maestro works on Mac OS X 10 7 and we can assist with advanced technical issues but most of our tech support staff does not use Macs so basic support for Mac OS X is limited 1 Overview Page 13 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 2 Contacting Pololu You can check the product page of your particular Maestro model for additional information We would be delighted to hear from you about any of your projects and about your experience with the Maestro You can contact us http www pololu com contact directly or post on our forum http forum pololu com Tell us what we did well what we could improve what you would like to see in the future or anything else you would like to say 2 Contacting Pololu Page 14 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 3 Getting Started 3 a Installing Windows Drivers and Software Y If you are using Windows XP you will need to have Service Pack 3 http www microsoft com downloads details aspx FamilyId 68C48D A D BC34 40BE 8D85 6BB4F56F5110 installed before installing the drivers for the Maestro See below for details Before you connect your Maestro to a computer running Microsoft Windows you should install its drivers 1 Download the Maestro Servo Controller Windows Drivers and Software http www pololu com file download maestro windows 130422 zip file_
77. nnel 12 Ry channel 13 lt mo channel 14 As channel 15 GND HHW HIE channel 16 SV out EEE E E ON E channel 17 signal SE E S O VSRV 3388 SRISS Mini Maestro 24 channel USB servo controller fully assembled labeled top view 81 wi servo power O 2001 2014 Pololu Corporation Note This section applies to the Mini Maestro 12 18 and 24 servo controllers Please see Section 1 a for Micro Maestro pinout and component information The Pololu Mini Maestro 12 18 and 24 channel servo controllers can connect to a computer s USB port via a USB A to mini B cable not included The USB connection is used to configure the servo controller It can also be used to send commands to the servo controller get information about the servo controller s current state and send and receive TTL serial bytes on the TX and RX lines http www pololu com product 130 1 Overview Page 10 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation The processor and the servos can have separate power supplies Processor power must come either from USB or from an external 5 16V power supply connected to the VIN and GND inputs on the E GND ground 0V left side of the board It is safe to have an external power supply ye is connected at the same time that USB is connected in that case the i REDE O VSRV servo voltage processor will be powered from the external supply Note that
78. nses to serial commands or arbitrary bytes sent from the computer via the USB connection or they come from the TXIN line 1 Overview Page 11 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation The RST pin can be driven low to reset the Maestro s microcontroller but this should not be necessary for typical applications The line is internally pulled high so it is safe to leave this pin unconnected Driving RST low is roughly equivalent to powering off the Maestro it will not reset any of the configuration parameters stored in non volatile memory To reset the configuration parameters select Device gt Reset to default settings in the Maestro Control Center The ERR line is an output that is tied to the red error user LED It is driven high when the red LED is on and it is a pulled low through the red LED when the red LED is off The red LED turns on when an error occurs turns off when the error flags have been cleared and can also be controlled by the user script Since the ERR line is never driven low it is safe to connect the ERR line of multiple Mini Maestros together Please note however that doing this will cause the red LEDs of all connected Mini Maestros to turn on whenever one of the Mini Maestros turns on its red LED For more information on the possible error conditions and response options please see Section 4 b The TXIN line is a serial input line that makes it easy to chain together mul
79. nt on the TX line A USB connection to a PC is not required though an RX only Comand Port is available on the PC for debugging or other purposes Connections Connect the TX line of the master device to the RX lines of all of the slave devices Commands sent by the master will then be received by all slaves Receiving serial responses from one of the slave devices on the PC can be achieved by connecting the TX line of that slave device to the RX line of the Maestro Receiving serial responses from multiple slave devices is more complicated Each device should only transmit when requested so if each device is addressed separately multiple devices will not transmit simultaneously However the TX outputs are driven high when not sending data so they cannot simply be wired together Instead you can use an AND gate as shown in the diagram to combine the signals Note that in many cases receiving responses is not necessary and the TX lines can be left unconnected Y Whenever connecting devices remember to wire the grounds together and ensure that each device is properly powered Unpowered devices with a TTL serial port can turn on or partially on drawing power from the serial line which means that extra care must be taken when turning power off and on to reset the devices Sending commands The Pololu Protocol or Mini SSC protocol should be used when multiple Pololu devices are receiving the same serial data This allows the devices to be
80. oise this will prevent the random jumping Note that this example will only work if you connect your potentiometer to one of the analog input capable channels channels 0 11 The inputs on the other channels are digital Using a button or switch to control servos It is possible to connect a button or switch to a Maestro and detect the state of the button in your script The script below moves a servo through a predefined sequence of movements advancing to the next step each time the button is pushed It uses channel 0 for the button and channel for the servo The button channel must be configured as an input and wired correctly See Section 7 b for instructions on how to wire a button to your Maestro using a pull up resistor so that the input is normally high and when the button is pressed it goes low goto main_loop Run the main loop when the script starts see below This subroutine returns 1 if the button is pressed 0 otherwise To convert the input value 0 1023 to a digital value 0 or 1 representing the state of the button we make a comparison to an arbitrary threshold 500 This subroutine puts a logical value of 1 or a 0 on the stack depending on whether the button is pressed or not sub button 6 The Maestro Scripting Language Page 60 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 0 get_position 500 less than return This subroutine uses the BUTTON subroutine a
81. olling the Maestro s outputs and for monitoring its status in real time A separate row of controls is displayed for each of the Maestro s channels In the screenshot above there are 12 channels displayed because the Maestro Control Center is connected to the Mini Maestro 12 channel servo controller When the Maestro Control Center connects to Maestro models with more or fewer channels it displays more or fewer channels on the screen For a channel configured as a servo or output the checkbox enables the output dragging the slider adjusts the target setting of the channel and the green ball indicates the channel s current position For example if the channel is set to a relatively slow speed when the slider is moved to a new position the green ball will slowly move until it has reached the slider indicating that the output has reached its target For more precise control a target value may also be entered directly into the Target input box The slider is automatically scaled to match the minimum and maximum values specified in the Settings tab For a channel configured as input the slider green ball Target and Position display the current value of the input There is no control available for inputs The inputs on channels 0 11 are analog their values range from 0 to 255 75 representing voltages from 0 to 5 V The inputs on channels 12 23 are digital their values are either exactly 0 or exactly 255 75 4 Using t
82. olu Corporation Found New Hardware Wizard Completing the Found New Hardware Wizard The wizard has finished installing the software for F Pololu Micro Maestro 6 Servo Controller pa Click Finish to close the wizard If you use Windows XP and experience problems installing or using the serial port drivers the cause of your problems might be a bug in older versions of Microsoft s usb to serial driver usbser sys Versions of this driver prior to version 5 1 2600 2930 will not work with the Maestro You can check what version of this driver you have by looking in the Details tab of the Properties window for usbser sys in C Windows System32 drivers To get the fixed version of the driver you will need to install Service Pack 3 http www microsoft com downloads details aspx FamilyId 68C48DAD BC34 40BE 8D85 6BB4F56F5110 If you do not want Service Pack 3 you can try installing Hotfix KB918365 instead but some users have had problems with the hotfix that were resolved by upgrading to Service Pack 3 The configuration software will work even if the serial port drivers are not installed properly After installing the drivers if you go to your computer s Device Manager and expand the Ports COM amp LPT list you should see two COM ports the Command Port and the TTL Port In parentheses after these names you will see the name of the port e g COMS5S or COM6 If you expand the Pololu USB Devices l
83. on parameter to identify which protocol you are using and you can freely mix commands in the three protocols 5 d Cyclic Redundancy Check CRC Error Detection For certain applications verifying the integrity of the data you are sending and receiving can be very important Because of this the Maestro has optional 7 bit cyclic redundancy checking which is similar to a checksum but more robust as it can detect errors that would not affect a checksum such as an extra zero byte or bytes out of order Cyclic redundancy checking can be enabled by checking the Enable CRC checkbox in the Serial Settings tab of the Maestro Control Center application In CRC mode the Maestro expects an extra byte to be added onto the end of every command packet except Mini SSC command packets The most significant bit of this byte must be cleared and the seven least significant bits must be the 7 bit CRC for that packet If this CRC byte is incorrect the Maestro will set the Serial CRC error bit in the error register and ignore the command The Maestro does not append a CRC byte to the data it transmits in response to serial commands 5 Serial Interface Page 39 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation A detailed account of how cyclic redundancy checking works is beyond the scope of this document but you can find a wealth of information using Wikipedia http en wikipedia org wiki Cyclic_redundancy_check
84. on time and period are both encoded with 7 bits per byte in the same way as the target in command 0x84 above For more information on PWM see Section 4 a The PWM output is not available on the Micro Maestro Get Position Compact protocol 0x90 channel number Pololu protocol OxAA device number 0x10 channel number Response position low 8 bits position high 8 bits This command allows the device communicating with the Maestro to get the position value of a channel The position is sent as a two byte response immediately after the command is received If the specified channel is configured as a servo this position value represents the current pulse width that the Maestro is transmitting on the channel reflecting the effects of any previous commands speed and acceleration limits or scripts running on the Maestro If the channel is configured as a digital output a position value less than 6000 means the Maestro is driving the line low while a position value of 6000 or greater means the Maestro is driving the line high If the channel is configured as an input the position represents the voltage measured on the channel The inputs on channels 0 11 are analog their values range from 0 to 1023 representing voltages from 0 to 5 V The inputs on channels 12 23 are digital their values are either exactly 0 or exactly 1023 Note that the formatting of the position in this command differs from the target speed acceleration formatting in the
85. op PICK EES takes a number n between 0 and 63 then puts the nth number below the top onto the stack 0 PICK is equivalent to DUP SWAP A swaps the top two numbers ROT ve permutes the top three numbers so that the 3rd becomes the top and the others move down bea one position ROLL A takes a number n then permutes the top n numbers so that the n th becomes the top and all of the others move down one PEEK A Mini Maestro 12 18 and 24 only takes a number n then copies the nth value on the stack gt measured from the bottom to the top of the stack POKE 24 Mini Maestro 12 18 and 24 only takes a number n then removes the next value from the stack and puts it at the nth location on the stack measured from the bottom Mathematical commands unary These commands take a single argument from the top of the stack then return a single value as a result Some of these have equivalents in C and most other languages listed in the C equivalent column below We use false to mean 0 and true to mean any non zero value A command returning true always returns a 1 command C equivalent description BITWISE NOT l inverts all of the bits in its argument LOGICAL NOT replaces true by false false by true NEGATE replaces x by x POSITIVE none true if and only if the argument is greater than zero NEGATIVE none true if and only if the argument is less than zero NONZERO none true 1 if and only if
86. or most applications using serial control it is a good idea to check errors continuously and take appropriate action if errors occur Go Home Compact protocol 0xA2 Pololu protocol OxAA device number 0x22 This command sends all servos and outputs to their home positions just as if an error had occurred For servos and outputs set to Ignore the position will be unchanged 3 Note For servos marked Off if you execute a Set Target command immediately after Go Home it will appear that the servo is not obeying speed and acceleration limits In fact as soon as the servo is turned off the Maestro has no way of knowing where it is so it will immediately move to any new target Subsequent target commands will function normally 5 f Serial Script Commands The Maestro has several serial commands for controlling the execution of the user script Stop Script Compact protocol 0xA4 Pololu protocol OxAA device number 0x24 This command causes the script to stop if it is currently running Restart Script at Subroutine Compact protocol 0xA7 subroutine number Pololu protocol 0xAA device number 0x27 subroutine number This command starts the script running at a location specified by the subroutine number argument The subroutines are numbered in the order they are defined in your script starting with 0 for the first subroutine The first subroutine is sent as 0x00 for this command the second as 0x01 etc To find th
87. other types of button control Using multiple buttons or switches to control servos This script demonstrates how to connect your Maestro to multiple buttons When a button is pressed it runs the corresponding sequence When the script is not doing anything else this loop will listen for button presses When a button is pressed it runs the corresponding sequence begin button_a if sequence_a endif button_b if sequence_b endif 6 The Maestro Scripting Language Page 61 of 73 Pololu Maestro Servo Controller User s Guide repeat button is pressed button b is assigned button _c is assigned Channel Settings tab b button_a Q e Sh SE SE SE SE SHE e return sub button b return sub button_c button c if sequence _ c endif to channel 1 and to channel 2 0 get position 500 less than 1 get position 500 less than 2 get position 500 less than return These subroutines each return 1 if the corresponding and return 0 otherwise Currently button a is assigned to channel 0 These channels must be configured as Inputs in the These subroutines each perform an arbitrary sequence You should change these to fit of servo movements your application sub sequence a 4000 3 servo 1000 delay 6000 3 servo 500 delay return sub sequence b 8000 4 servo 900 delay 7000 4 servo 900 delay 6000 4 servo 900 delay return sub sequence c 10 4 speed 7000 4 servo 3000 delay 6000 4 servo
88. output for PWM to be available One 816057 Unts 1 48 ya 20 f ra You may use the PWM Output control at the bottom of the Status tab to test out PWM by checking the checkbox and entering specific values for the on time and period in units of 1 48 us A period of 4800 for example will generate a frequency of 10 kHz The resolution on these values depends on the period as shown in the table below The PWM Output control in the Status tab in the Maestro Control Center only available on the Mini Maestro 12 18 and 24 Period Period On time range resolution resolution 1 1024 4 1 1025 4096 16 4 4097 16384 64 16 The special periods 1024 4096 and 16384 are not recommended since 100 duty cycle is not available at these values If the on time is set equal to the period at one of the special values the duty cycle will be 0 a low output The periods 1020 47 1 kHz 4080 11 7 kHz and 16320 2 9 kHz provide the best possible resolution with 100 and 0 duty cycle options so you should use one of these periods if possible You will probably want to use serial commands or a script to make use of PWM in your project See Section 5 e and Section 6 b for more information 4 Using the Maestro Control Center Page 23 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation 4 b Errors bi Pololu Maestro Control Center File Device Edit
89. r Mini Maestros and can generate a wide range of pulses to allow maximum responsiveness and range from modern servos Units can be daisy chained with additional Pololu servo and motor controllers on a single serial line 1 10 Miri Maestro 24 edhe 0J1970 4 ee 58 WJ Polotu 2010 Mini Maestro 18 ee U JE Bow Engage Your Brain www polotu com a e Engege Your Brain www polotu com oo WEY rx Rx ww 5946060900 Micro Maestro 6 Mini Maestro 12 Mini Maestro 18 Mini Maestro 24 aoe ee o ooje ume eee ele A free configuration and control program is available for Windows and Linux see Section 4 making it simple to configure and test the board over USB create sequences of servo movements for animatronics or walking robots and write step through and run scripts stored in the servo controller The Maestro s internal script memory allows storage of servo positions that can be automatically played back without any computer or external microcontroller connected see Section 6 The Maestros channels can also be used as general purpose digital outputs and analog or digital inputs providing an easy way to read sensors and control peripherals directly from a PC over USB These inputs can be used with the scripting system to enable creation of self contained animatronic displays that respond to external stimuli 1 Overview Page 3 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Polo
90. r Page 30 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation _ Period T Rate Speed units Acceleration units T 20ms 50Hz 0 25 us 10 ms 0 25 us 10 ms 80 ms T 3 19 ms gt 50 Hz 0 25 usy T 0 25 ps T 8T T gt 20 ms lt 50 Hz 0 25 us T 2 0 25 ps T 2 4T Servos available is an advanced option for the Micro Maestro only specifying the number of channels that may be used to control servos For example if this value is set to 4 only the channels 0 3 will be available as servo channels The other channels must all be set to Input or Output The only reasons to make fewer servos available are to allow a longer maximum pulse length or a shorter period Period multiplier is an advanced option for the Mini Maestro 12 18 and 24 that allows a larger period lower pulse rate on some of the channels For example if you select a period of 3 and a multiplier of 6 you can have some servos run at 3 ms 333 Hz and the others at 18 ms 55 Hz When the multiplier is greater than 1 the pulse rate options will be shown in each channel in the Rate column For the Mini Maestro 24 channel servo controller one extra option is available Enable pull ups on channels 18 20 turns on pull up resistors for all of the channels 18 20 that are configured as inputs This guarantees that the input value will be high when nothing else is driving the line When enabled this feature allows you to connec
91. r receives data over UDP and uses libusb to control two servos e Joystick controlled servos under Windows 7 in Perl http forum pololu com viewtopic php f 168 t 4766 C libusb example code http forum pololu com viewtopic php f 16 amp t 3620 e Visual C serial example code http forum pololu com viewtopic php f 16 amp t 3729 amp p 17585 p17585 e Visual Basic 6 VB6 serial example code http forum pololu com viewtopic php p 24711 p24711 PHP serial example code http forum pololu com viewtopic php f 16 amp t 5951 MATLAB serial example code http forum pololu com viewtopic php f 15 amp t 5090 amp p 24142 p24142 LabVIEW VI for Micro Maestro http forum pololu com viewtopic php f 23 amp t 4538 libusc https github com mojocorp Pololu_Maestro This project contains a library named libusc that is written in C and uses libusb to expose almost every part of the Maestro s native USB protocol It also has an example GUI written with Qt Pololu USB SDK http www pololu com docs 0J41 This is the official source for information about the Maestro s native USB interface It contains example code written in C Visual C and Visual Basic NET More information is in Section 8 Commercial software These software packages have integrated support for the Maestro e Maestro support for RoboRealm http www roborealm com help Pololu_Maestro php e Robodyssey Servo Scriber Software http www robodyssey co
92. re the button or switch between the E signal line and GND 0 V so that when the button switch is active the EF input will fall to 0 V The picture to the right shows how to connect a button or switch to channel 0 on the Micro Maestro 6 channel servo 1 100kQ button or pull up resistor switch Diagram for connecting a button or switch to the Micro Maestro Servo controller Controller Note An external pull up resistor is not needed if you use channel 18 19 or 20 on the Mini Maestro 24 channel servo controller and enable its internal pull up resistor in Channel Settings tab of the Maestro Control Center You can test your input by toggling the button switch and verifying that the Position variable as shown in the Status tab of the Maestro Control Center reflects the state of your button switch it should be close to 255 75 when the button switch is inactive and close to 0 when it is active Now you can read the state of the button switch in your script using the GET POSITION command or over serial using the Get Position command These commands will return values that are close to 1023 when the button switch is inactive and close to 0 when it is active Potentiometer To connect a potentiometer to the Maestro you must first decide which potentiometer gt 1 kQ channel you would like to use If you have the Mini Maestro 18 or 24 channel servo controller be sure to pick one of the analog input capable channels channels
93. rl or Shift buttons while clicking on them This allows you to quickly move delete set the duration of cut copy or save over several frames at once e You can drag any of the tabs out of the main window in to their own windows If you drag the Sequence tab out of the window then you will be able to see the Status tab and the Sequence tab at the same time e You can cut copy and paste frames by selecting them and then using the Edit menu or the standard keyboard shortcuts Frames are stored on the clipboard as tab separated text so you can cut them from the frame list paste them in to a spreadsheet program edit them and then copy them back in to the frame list when you are done This feature does not work in Linux Keyboard Shortcuts The following keyboard shortcuts can be used in the frame list e Ctri A Select all frames e Ctrl C Copy selected frames e Ctrl V or Shift Insert Paste insert frames from clipboard e Ctrl X Cut selected frames e Ctrl Up Move selected frames up e Ctrl Down Move selected frames down e Del Delete selected frames 4 Using the Maestro Control Center Page 27 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 4 d Entering a Script EN Pololu Maestro Control Center File Device Edit Help Connected to 00000101 w Firmware version 1 00 Error code 00000 Status Errors Channel Settings Serial Settings Sequence Script Code Run s
94. roller User s Guide 2001 2014 Pololu Corporation putc OxAA putc 0x0C putc 0x04 putc 0x00 putc 0x70 Target position 1500 us typical neutral for servos putc 0x2E 1 delay ms 1000 5 h 4 Bash script The following shell script sends Set Target commands to the Maestro s virtual COM port This script allows you to easily control a Maestro over USB from a computer running Linux or Mac OS X 10 7 Lion or later To use it you will need to first run the Maestro Control Center on a Linux or Windows computer and set the Maestro s serial mode to USB Dual Port Then on the computer you want to control the Maestro from you should copy the code below into a file named maestro set target sh You can run it using the example commands given below You will need to change the DEVICE argument to be the name of the Maestro s Command Port see Section 5 a bin bash Sends a Set Target command to a Pololu Maestro servo controller via its virtual serial port Usage maestro set target sh DEVICE CHANNEL TARGET Linux example bash maestro set target sh dev ttyACMO 0 6000 Mac OS X example bash maestro set target sh dev cu usbmodem00234567 0 6000 Windows example bash maestro set target sh USBSERO0OO0O 0 6000 Windows example bash maestro set target sh COM6 0 6000 CHANNEL is the channel number TARGET is the target in units of quarter microseconds The Maestro must be configured to be in USB Dual Port
95. run scripts stored in the servo controller Two ways to write software to control the Maestro from a PC o Virtual COM port makes it easy to send serial commands from any development environment that supports serial communication o Pololu USB Software Development Kit http www pololu com docs 0J41 allows use of more advanced native USB commands and includes example code in C Visual Basic NET and Visual C The Channel Settings tab in the Maestro Control Center TTL serial features gt Supports 300 200 000 bps in fixed baud mode 300 115 200 bps in autodetect baud mode The Status tab in the Maestro Control Center e Simultaneously supports the Pololu protocol which gives access to advanced functionality and the simpler Scott Edwards MiniSSC II protocol there is no need to configure the device for a particular protocol mode Can be daisy chained with other Pololu servo and motor controllers using a single serial transmit line o Chain input allows reception of data from multiple Mini Maestros using a single serial receive line without extra components does not apply to Micro Maestros o Can function as a general purpose USB to TTL serial adapter for projects controlled from a PC Board can be powered off of USB or a 5 16 V battery and it makes the regulated 5V available to the user e Upgradable firmware 1 Overview Page 5 of 73 Pololu Maestro Servo Controller User s Guide Maestro Compari
96. s 0x84 Command byte Set Target channel First data byte holds channel number target amp Ox7F Second byte holds the lower 7 bits of target target gt gt 7 amp 0x7F Third data byte holds the bits 7 13 of target serialBytes 0 serialBytes 1 serialBytes 2 serialBytes 3 Many servo control applications do not need quarter microsecond target resolution If you want a shorter and lower resolution set of commands for setting the target you can use the Mini SSC command below Set Target Mini SSC protocol Mini SSC protocol OxFF channel address 8 bit target This command sets the target of a channel to a value specified by an 8 bit target value from 0 to 254 The 8 bit target value is converted to a full resolution target value according to the range and neutral settings stored on the Maestro 5 Serial Interface Page 41 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation for that channel Specifically an 8 bit target of 127 corresponds to the neutral setting for that channel while 0 or 254 correspond to the neutral setting minus or plus the range setting These settings can be useful for calibrating motion without changing the program sending serial commands The channel address is a value in the range 0 254 By default the channel address is equal to the channel number so it should be from 0 to 23 To allow multiple Maestros to be controlled on the same serial line set t
97. s Asynchronous serial output can also be bit banged by a standard digital output line under software control The data format is 8 data bits one stop bit with no parity which is often expressed as 8 N 1 The diagram below depicts a typical asynchronous non inverted TTL serial byte LSB MSB y 10011010 cc ov ULI UU ys 2 start bit stop bit Diagram of a non inverted TTL serial byte A non inverted TTL serial line has a default non active state of high A transmitted byte begins with a single low start bit followed by the bits of the byte least significant bit LSB first Logical ones are transmitted as high VCC and logical zeros are transmitted as low 0 V which is why this format is referred to as non inverted serial The byte is terminated by a stop bit which is the line going high for at least one bit time Because each byte requires a start bit 8 data bits and a stop bit each byte takes 10 bit times to transmit so the fastest possible data rate in 5 Serial Interface Page 37 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation bytes per second is the baud rate divided by ten At the Maestro s maximum baud rate of 250 000 bits per second the maximum realizable data rate with a start bit coming immediately after the preceding byte s stop bit is 25 000 bytes per second Y Whenever connecting devices remember to wire the grounds together and ensure that ea
98. s acceleration high bits Pololu protocol OxAA device number 0x09 channel number acceleration low bits acceleration high bits This command limits the acceleration of a servo channel s output The acceleration limit is a value from 0 to 255 in units of 0 25 us 10 ms 80 ms except in special cases see Section 4 e A value of 0 corresponds to no 5 Serial Interface Page 42 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation acceleration limit An acceleration limit causes the speed of a servo to slowly ramp up until it reaches the maximum speed then to ramp down again as position approaches target resulting in a relatively smooth motion from one point to another With acceleration and speed limits only a few target settings are required to make natural looking motions that would otherwise be quite complicated to produce At the minimum acceleration setting of 1 the servo output takes about 3 seconds to move smoothly from a target of 1 ms to a target of 2 ms The acceleration setting has no effect on channels configured as inputs or digital outputs Set PWM Mini Maestro 12 18 and 24 only Compact protocol 0x8A on time low bits on time high bits period low bits period high bits Pololu protocol OxA A device number 0x0A on time low bits on time high bits period low bits period high bits This command sets the PWM output to the specified on time and period in units of 1 48 us The
99. s Guide 2001 2014 Pololu Corporation goto mylabel any code here is skipped 4000 1 servo mylabel the program continues here 4000 2 servo In this example only servo 2 will get set to 4000 while servo 1 will be unchanged Subroutines It can be useful to use the same sequence of commands many times throughout your program Subroutines are used to make this easier and more space efficient For example suppose you often need to set servo and servo 2 back to their neutral positions of 6000 1 5 ms using the sequence 6000 1 servo 6000 2 servo You can encapsulate this in a subroutine as follows sub neutral 6000 1 servo 6000 2 servo return Then whenever you want send these two servos back to neutral you can just use neutral as a command More advanced subroutines take values off of the stack For example the subroutine sub set servos 2 servo 1 servo return will set channel 2 to the value on the top of the stack and channel 1 to the next value So if you write 4000 6000 set_servos your script will set channel 1 to 4000 and channel 2 to 6000 Subroutines can call other subroutines up to a limit of 10 levels of recursion For example the subroutine neutral above can be implemented by calling set_servos sub neutral 6000 6000 set_servos return 6 b Command Reference The following is the entire list of commands and keywords in the Maestro script language The stack effect column
100. s are not equal PLUS SHIFT_LEFT adds the arguments shifts the binary representation of the second argument to the left by a number of bits given in the second argument without wrapping SHIFT_RIGHT TIMES shifts the binary representation of the first argument to the right by a number of bits given in the second argument without wrapping multiplies the arguments 6 The Maestro Scripting Language Page 55 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Servo LED and other output commands command eer description SPEED sets the speed of the channel specified by the top element to the value in the second element see Section 4 e sets the acceleration of the channel specified by the top element to the value in ACOELERATINY the second element see Section 4 e GET_POSITION 1 1 gets the position of the channel specified by the top element GET MOVING STATE 1 true if any servos that are limited by speed or acceleration settings are still moving sets the target of the channel specified by the top element to the value in the SERVO 2 second element in units of 0 25 ps sets the target of the channel specified by the top element to the value in the SERVO_8BIT 2 second element which should be a value from 0 to 254 see the Mini SSC command in Section 5 e LED_ON none turns the red LED on LED_OFF none turns the red LED off assuming no errors
101. s easy to write subroutines for delays of hours days weeks or whatever you want Keep in mind however that the timer on the Micro Maestro is not as accurate as a stopwatch these delays could easily be off by 1 Digital output The digital output feature of the Maestro is capable of controlling anything from simple circuits to intelligent devices such as the ShiftBrite LED Modules http www pololu com product 1222 and ShiftBar LED Controllers http www pololu com product 1242 which use a simple synchronous serial protocol In this example the clock latch and data pins of a ShiftBrite or ShiftBar are connected to servo channels 0 1 and 2 respectively and these channels are all configured as outputs The subroutine RGB defined here takes 10 bit red green and blue values from the stack then sends a 32 byte color packet and toggles the latch pin to update the ShiftBrite with the new color value The subroutine could be modified to control a larger chain of ShiftBrites if desired begin 1023 0 0 rgb 500 delay red 0 1023 0 rgb 500 delay green 0 0 1023 rgb 500 delay blue repeat Connecting the Micro Maestro to a chain of ShiftBars A single 12V supply powers all of the devices Subroutine for setting the RGB value of a ShiftBrite ShiftBar example usage 1023 511 255 rgb sub rgb 0 send bit this bit does not matter 0 send bit the address bit 0 means a color command swap rot rot send 10 bit va
102. s that use a compatible protocol This section contains no new information about the Maestro all of the information in this section can be deduced from the definitions of the three serial modes Section 5 a and the serial protocols used by the Maestro Section 5 c First of all you will need to decide whether to use the Pololu protocol the Mini SSC protocol or a mix of both You must make sure that no serial command you send will cause unintended operations on the devices it was not addressed to If you want to daisy chain several Maestros together you can use a mixture of both protocols If you want to daisy chain the Maestro with other devices that use the Pololu protocol you can use the Pololu protocol If you want to daisy chain the Maestro with other devices that use the Mini SSC protocol you can use the Mini SSC protocol Secondly assign each device in the project a different device number or Mini SSC offset so that they can be individually addressed by your serial commands For the Maestro this can be done in the Serial Settings tab of the Maestro Control Center application The following diagram shows how to connect one master and many slave devices together into a chain Each of the devices may be a Maestro or any other device such as a jrk http www pololu com product 1392 qik http www pololu com product 1110 or other microcontroller Pololu USB device Serial devices using or microcontroller Pololu protocol Daisy cha
103. son Table Channels Analog input channels Digital input channels Width Length Weight Configurable pulse rated Pulse range Script size 1 This is the weight of the board without header pins or terminal blocks Micro Maestro 6 6 0 0 85 2 16 cm 1 20 3 05 cm 3 0 g 33 100 Hz 64 3280 us 1KB Mini Maestro 12 12 12 0 1 10 2 79 cm 1 42 3 61 cm 4 2g 1 333 Hz 64 4080 us 8 KB O 2001 2014 Pololu Corporation Mini Maestro 18 18 12 6 1 10 2 79 cm 1 80 4 57 cm 4 9 g 1 333 Hz 64 4080 us 8 KB Mini Maestro 24 24 12 112 1 10 2 79 cm 2 30 5 84 cm 6 0 g 1 333 Hz 64 4080 us 8 KB 2 The available pulse rate and range depend on each other and factors such as baud rate and number of channels used See Section 9 for details 3 The user script system is more powerful on the Mini Maestro than on the Micro Maestro See Section 6 d for details 1 Overview Page 6 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Application Examples e Serial servo controller for multi servo projects e g robot arms animatronics fun house displays based on microcontroller boards such as the BASIC Stamp Orangutan robot controllers http www pololu com category 8 robot controllers or Arduino platforms e Computer based servo control over USB port e Computer interface for sensors
104. stro The result of loading the wrong firmware is that your Maestro will have corrupted unusable firmware The Maestro will not be recognized by your computer and it will probably not blink any of its LEDs In this case the normal method for getting the Maestro into bootloader mode through the Maestro Control Center will not work and you will have to resort to a hard bootloader reset After that the Maestro will be in bootloader mode and you can restore the Maestro s correct firmware 1 To perform a hard bootloader reset first make sure the Maestro is powered off It is best if you can just disconnect everything from it 2 Using a screwdriver a small piece of wire or some other conductive tool short the two exposed bootloader pads together The pads are shown in the pictures below 9 E oe NN 3 gt ie Meili iiiit 4s TETT za Bootloader pads for the Micro Maestro 6 Channel USB Servo Controller 4 Using the Maestro Control Center Page 33 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation Bootloader pads for the Mini Maestro 12 18 or 24 Channel USB Servo Controller 3 While the pads are shorted together connect the Maestro to USB Usually the easiest way to do this is to have one end of the USB cable already plugged into the Maestro and connect the other end to the computer after you have shorted the pads This might require a few tries Once it works you should see
105. t buttons or switches to channels 18 19 or 20 without supplying your own external pull up resistor simply connect the button switch between ground and signal line 4 f Upgrading Firmware Please do not attempt to upgrade your Maestro s firmware unless you know what you are doing Most customers do not need to upgrade their firmware The firmware is the program that runs on the Maestro The Maestro has field upgradeable firmware that can be easily updated with bug fixes or new features There are four types of Maestros the Micro Maestro 6 Channel USB Servo Controller usc02a the Mini Maestro 12 Channel USB Servo Controller usc03a the Mini Maestro 18 Channel USB Servo Controller usc03b and the Mini Maestro 24 Channel USB Servo Controller usc03c Each type of Maestro has its own firmware and you cannot load the firmware for one type onto another Firmware Versions e Firmware Version 1 00 This is the original version of the firmware Currently all Mini Maestros still ship with this version of the firmware Firmware Version 1 01 for the Micro Maestro 6 Channel USB Servo Controller This firmware version was released for the Micro Maestro only It contains a bug fix that makes Ignore mode servos behave correctly at startup All Micro Maestros shipped on or after November 19 2009 come with this firmware version e Firmware Version 1 02 This firmware version was released on 2013 06 20 for all four types of Maestros
106. the Micro Maestro or 744 servo positions in the 8192 byte memory of the Mini Maestros To get the most out of the limited memory there are a variety of ways to compress the program Most important is to make use of subroutines For example since we repeat the instructions 0 servo 500 delay several times we can move them into a subroutine to save space At the same time this simplifies the code and makes it easier to make future modifications such as changing the speed of the entire sequence Move servo 0 to five different positions in a loop begin 4000 frame 5000 frame 6000 frame 7000 frame 8000 frame repeat sub frame 0 servo 500 delay return 6 The Maestro Scripting Language Page 57 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Using the subroutine brings the script down to 31 bytes 4 per position and 11 bytes of overhead for the loop and to define FRAME We can go further inspecting the compiled code shows that putting each number on the stack requires 3 bytes one byte as a command and two for the two byte number Numbers from 0 to 255 can be loaded onto the stack with just two bytes Suppose in our application we do not need the full 0 25 us resolution of the device since all of our settings are multiples of 100 Then we can use smaller numbers to save another byte Move servo 0 to five different positions in a loop begin 40 frame 50 frame 60 frame 70 frame
107. the servo controller s current state and send and receive TTL serial bytes on the TX and RX lines The processor and the servos can have separate power supplies Processor power must come either from USB or from an external 5 16V power supply connected to the VIN and GND inputs It is safe to have an external power supply connected at the same time that USB is connected in such cases the processor will be powered from the external supply Note that if the external supply falls below 5 V correct operation is not guaranteed even if USB is also connected E GND ground 0v VIN 5 16V board voltage Servo power connections are provided in the upper right corner of vsrv servo voltage 5V regulator output the Micro Maestro board Servo power is passed directly to the servos without going through a regulator so the only restrictions on your servo power supply are that it must be within the operating range of your servos and provide enough current for your application Please consult the datasheets for your servos to determine an appropriate servo power source and note that a ballpark figure for the current draw of an average straining servo is 1 A Micro Maestro power pins You can power the Maestro s processor and servos from a single power e OY supply by connecting the positive power line to both VIN and the servo MET ct MN O power ports An easy way to accomplish this on the Micro Maestro is to 7 A 3 solder a wire on th
108. tile dete tints Th SA et ON de Ae elt des ta lady 35 Sps FPS EAN AA ee ee el a Bh ue he A ey BR Sh a ee Re Ee 37 5 c Comimnand Protocols ii bist A ace hh te aye Be Bw Se A tg a 38 5 d Cyclic Redundancy Check CRC Error Detection 2 o e a 39 5 e Serial Servo Commands s pea ahe a e a a a ee 41 SfeSerialiScrpt Commands 4c A E E a EE A RA a E E A E da e 44 5 2 Daisy Chaining ta to Ge a a ta tee ee ied 45 5Sh Senal Example Code ere Sale we SOLA ES A a ERE a 47 5 H Cross platformeC tdt E dd ed BE ES a bal cid amp 47 5h 2 Windows G ae eee Sve da PAS da Be Bh ear ea OS ER es 48 13 PICISEAS SO at a e dati aed et eid Oa ae eo eae Ee eon A 48 ShA Bashtoscrpt olas 6 44 6 Rb wie SESS SEES Se Ge ht RES td ARS 49 6 The Maestro Scripting Language 50 6 a Maestro Script Language Basics 2 ee 50 6 b Commiand Reference aa a Boi rnd ee Be ig ok EG ere 52 6 Example Scripts sic 60 5 4 5 cot hh A ae B Sete A See oR 56 6 d Script Specifications 4 a a A ds tl eA hk de Lol te des ta cloak y 64 Te Winne Examples a a aoe Ve A ee A Ae ee RE BG 65 Ta Powering the Maestro olin ee tte ek elie ad ee em ae ee a ht et 65 7 b Attaching Servos and Peripherals 2 ee 66 7 c Connecting toa Microcontroller 2 ee 68 8 Writing PC Software to Control the Maestro 2 ee ee 69 9 Maestro Settings Limitations aai gd e e a a aaa a a A e E ea e a e Aa a 70 10 Related RESOUICES 040 ie eee Ae Ae ee AAS e beh
109. time only O Yes now and every time connect a device No not this time Click Next to continue 7 On the second screen of the Found New Hardware Wizard select Install the software automatically and click Next 3 Getting Started Page 16 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation Found New Hardware Wizard This wizard helps you install software for Pololu Micro Maestro 6 Servo Controller f E K If your hardware came with an installation CD lt 6 or floppy disk insert it now What do you want the wizard to do Install the software automatically Recommended Install from a list or specific location Advanced Click Next to continue 8 Windows XP will warn you again that the driver has not been tested by Microsoft and recommend that you stop the installation Click Continue Anyway MAA Pease mad mide the md ds the sohase ES lhe Aeee a me rs Pe haaye J Pretty USE A Progr Prag ar Port Pr SE AE Peng gene Prag rr Poot hat rot ad Loge String mt coro P Lele nte tu wirta 4 w g EL 9 When you have finished the Found New Hardware Wizard click Finish After that another wizard will pop up You will see a total of three wizards when plugging in the Maestro Follow steps 6 9 for each wizard 3 Getting Started Page 17 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pol
110. tiple Mini Maestros Any serial bytes received on this line will be buffered through an AND gate and transmitted on the TX line See Section 5 g for more information about daisy chaining eee e ele Micro Maestro 6 Mini Maestro 12 Mini Maestro 18 Mini Maestro 24 Bottom view with dimensions in inches of Pololu Micro and Mini Maestro servo controllers The dimensions of the Mini Maestro PCBs are shown in the picture above along with the Micro Maestro for comparison The mounting holes have a diameter of 0 086 and are intended for 2 or M2 screws The vertical and horizontal distances between the two mounting holes are as follows 1 2 and 0 5 for the Mini Maestro 12 1 58 and 0 5 for the Mini Maestro 18 and 1 5 and 0 5 for the Mini Maestro 24 1 c Indicator LEDs The Maestro has three indicator LEDs e The green USB LED indicates the USB status of the device When the Maestro is not connected to a computer via the USB cable the green LED will be off When you connect the Maestro to USB the green LED will start blinking slowly The blinking continues until the Maestro receives a particular message from the computer indicating that the Maestro s USB drivers are installed correctly After the Maestro gets this message the green LED will be on but it will flicker briefly when there is USB activity The control center application constantly streams data from the Maestro so when the control center is running and connected
111. ttings tab of the Maestro Control Center bi Pololu Maestro Control Center Device Edit UART fixed baud rate 9600 cal UART detect baud rate E Enable CRC Device Number 12 Mini SSC offset 0 Timeout s 000 H E Never sleep ignore USB suspend The Serial Settings tab in the Maestro Control Center 5 Serial Interface Page 35 of 73 Pololu Maestro Servo Controller User s Guide O 2001 2014 Pololu Corporation The Maestro can be configured to be in one of three basic serial modes USB Dual Port In this mode the Command Port can Host PC Pololu USB devica Any serial device be used to send commands to the Maestro and receive fi it The baud Command PRA command responses rom 1t e au rate you set in your Port processing terminal program when opening the Command Port is irrelevant The TTL Port can be used to send bytes on TTL TOA the TX line and receive bytes on the RX line The Port RXL AIX baud rate you set in your terminal program when mode opening the TTL Port determines the baud rate used ds to receive and send bytes on RX and TX This allows The USB Dual Port serial mode your computer to control the Maestro and simultaneously use the RX and TX lines as a general purpose serial port that can communicate with other types of TTL serial devices USB Chained In this mode the Command Port Serial device using is used to both transmit bytes on the TX line and ee Pole SE device Paton
112. ust have the same pulse rate while on the Mini Maestro 12 18 an 24 you can have two different rates and choose which rate to use on each channel The pulse rates available are controlled by the Period and Period multiplier settings described below Min and Max specify the allowed values for the channel s position For channels configured as Servo outputs the Min and Max settings correspond respectively to the minimum and maximum allowed pulse widths for the servo in units of microseconds On startup or error This option specifies what value the target of the channel should have when the device starts up power up or reset or when there is an error Note that if there is a speed or acceleration setting for the channel the output will smoothly transition to the specified position on an error but not during start up since it has no information about the previous position of the servo in this case e Off specifies that the servo should initially be off have a value of 0 and that it should be turned off whenever an error occurs Ignore specifies that the servo should initially be off but that its value should not change on error e Go to specifies a default position for the servo The servo target will be set to this position on start up or when an error occurs Speed This option specifies the speed of the servo in units of 0 25 us 10 ms For example with a speed of 4 the position will change by at most 1 us per 10 ms or 100 0
113. ver you want to wait for all motion to stop before proceeding to the next step of a script Using an analog input to control servos An important feature of the Maestro is that it can be used to read inputs from sensors switches or other devices As a simple example suppose we want to use a potentiometer to control the position of a servo For this example connect the potentiometer to form a voltage divider between 5V and 0 with the center tap connected to channel 1 Configure channel 1 to be an input and examine the signal on the Status tab of the Maestro Control Center You should see the position indicator vary from 0 to 255 us as you turn the potentiometer from one side to the other In your script this range corresponds to numbers from 0 to 1023 We can scale this number up to approximately the full range of a servo then set the servo position to this number all in a loop Sets servo 0 to a position based on an analog input begin 1 get_position get the value of the pot 0 1023 4 times 4000 plus scale it to 4000 8092 approximately 1 2 ms 0 servo set servo 0 based to the value repeat Alternatively you might want the servo to go to discrete positions depending on the input value Set the servo to 4000 6000 or 8000 depending on an analog input begin 1 get_position get the value of the pot 0 1023 dup 300 less than if B 4000 go to 4000 for values 0 299 else dup 600 less than if 7 6000 go to 6000 for values
114. ves a pulse every 20 ms The user script is empty 3 Getting Started Page 21 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation 4 Using the Maestro Control Center The Maestro s USB interface provides access to all configuration options as well as support for real time control feedback and debugging The Maestro Control Center is a graphical tool that makes it easy for you to use the USB interface for almost any project you will want to start by using the control center to set up and test your Maestro This section explains most of the features of the Maestro and the Maestro Control Center 4 a Status and Real time Control Ei Pololu Maestro Control Center File Device Edit Help Connectedto 00000101 Firmware version 1 00 Name Mode Enabled Target Left am A Servo W lo msn Left am B Servo r _ 108475 Left arm C Servo s 2203 00 Right arm A Servo i 1496 0 Right amB Servo r y 1652502 Right arm C _ 2203 06 Neck r 114125 2 1500 00 2 1500 00 255 751 52 501 2000 0 yl j S a BAIR a a gt a P li oo wo w P E EE EE EE E E EE EF lt p gt EF 0 1 2 3 4 5 6 7 8 9 10 11 The Status tab in the Maestro Control Center The Status tab is used for contr
115. y each line of your script This is available mostly as a tool for developers if you are interested in the details of the bytecode used on the Maestro for example if you want to write your own compiler please contact us http www pololu com contact At the end of the compiled code is a listing of all of the subroutines including their numbers in decimal and hex notation These numbers can be used with serial commands to enter the subroutines under external control 4 e Channel Settings File Device Edit Help Connected to 00000101 Fimware version 1 00 Status Erors Channel Settings Serial Settings Sequence Sort Name Mode Rate Hz Min Max Speed Left am A Sex 92 200015 76h ale 1500 00 Left am B 56 2000144 30 2 Os 1200251 Left am C 704 2304 704005 0 o 1500 00 Right arm A 2000124 76 95 1500 0 Right arm B 992 51 2000 57 3012 Os 17992515 Right am C Ti 2308164 4 00 0 OS 1500251 Neck 3845 24642 384 1201 13 1352251 9924 20005 9200 JE JE o 1 2 3 4 5 6 7 8 9 10 11 The Channel Settings tab in the Maestro Control Center The Channel Settings tab contains controls for many of the channel related parameters that are stored on the Maestro affecting its operation immediately on start up A separate row of controls is displayed for each of the Maestro s channels Name Each of the channels may be assign
116. y necessary data bytes For example if we want to set the target of servo 0 to 1500 us we could send the following byte sequence in hex 0x84 0x00 0x70 0x2E in decimal 132 0 112 46 The byte 0x84 is the Set Target command the first data byte 0x00 is the servo number and the last two data bytes contain the target in units of quarter microseconds Pololu Protocol This protocol is compatible with the serial protocol used by our other serial motor and servo controllers As such you can daisy chain a Maestro on a single serial line along with our other serial controllers including additional Maestros and using this protocol send commands specifically to the desired Maestro without confusing the other devices on the line To use the Pololu protocol you transmit OxAA 170 in decimal as the first command byte followed by a Device Number data byte The default Device Number for the Maestro is 12 but this is a configuration parameter you can 5 Serial Interface Page 38 of 73 Pololu Maestro Servo Controller User s Guide 2001 2014 Pololu Corporation change Any Maestro on the line whose device number matches the specified device number accepts the command that follows all other Pololu devices ignore the command The remaining bytes in the command packet are the same as the compact protocol command packet you would send with one key difference the compact protocol command byte is now a data byte for the command 0xAA and hen
117. you are still unable to connect to it see the instructions in Section 4 f 1 for doing a hard bootloader reset 7 Go to the Device menu and select Upgrade firmware You will see a message asking you if you are sure you want to proceed click OK 8 If you are using Windows XP and see a Found New Hardware Wizard window appear then you should follow steps 6 8 from Section 3 a to get the bootloader s driver working 9 Once the Maestro is in bootloader mode and the bootloader s drivers are properly installed the green LED should be blinking in a double heart beat pattern and there should be an entry for the bootloader in the Ports COM amp LPT list of your computer s Device Manager 10 Go to the window entitled Firmware Upgrade that the Maestro Control Center has opened 11 Click the Browse button and select the firmware file you downloaded Make sure that the selected file is the right file for your type of Maestro see steps 2 and 3 12 Select the COM port corresponding to the bootloader If you do not know which COM port to select go to the Device Manager and look in the Ports COM amp LPT section 13 Click the Program button You will see a message warning you that your device s firmware is about to be erased and asking you if you are sure you want to proceed click Yes 4 Using the Maestro Control Center Page 32 of 73 Pololu Maestro Servo Controller User s Guide 2001

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