ServoCenter 3.1 Chip
Contents
1. Rate Select Pins Package RATESELECTO Pin RATESELECTI Pin PDIP 26 23 TQFP 23 22 PLCC 29 28 20 User s Manual 6 Programming the ServoCenter 3 1 Chip 6 1 ServoCenter 3 1 Protocol 6 1 1 Protocol Overview The ServoCenter 3 1 controller receives messages from the controlling system in the form of sequences of serial communication bytes called packets Each byte is serial encoded using 8N1 serial encoding 8 data bits no parity and stop bit The packet size can range from three to six bytes in length depending upon the nature of the command being sent to the controller Each packet consists of an initial start of packet byte which includes a board ID specifier followed by a command value specifier byte followed by zero to three command data bytes and terminated by a packet checksum value byte The ServoCenter 3 1 controller buffers the incoming command stream and will only take an action once the entire packet has been received and the checksum has been verified as correct Incomplete packets packets with inappropriate chip IDs and packets with incorrect checksums will be ignored This allows the controlling system to send command data at leisure without loss of function The command buffer will however be cleared whenever the ServoCenter controller is either reset or powered Most ServoCenter commands return no result data Certain commands however are designe2. ES 0 80 TYP User s Manual 4 2 Electrical 4 2 1 Absolute Maximum Ratings Operating Temperature 55 C to 125 C Storage Temperature 65 C to 150 C Voltage on any pin except RESET with 0 5V to Vpp 0 5V respect to Ground Voltage on RESET with respect to 0 5V to 13 0V Ground Maximum Operating Voltage 6 0V DC Current per I O pin 40 0 mA DC Current Vpp and GND pins 200 0 mA Notice Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the ServoCenter Chip This is a stress rating only and functional operation of the chip at these or other conditions beyond those indicated here is not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability 4 2 2 DC Characteristics 40 C to 85 2 7V to 5 5V Unless Otherwise Noted Symbol Parameter Condition Min Max Units Supply Voltage 24 5 5 V ow 0 5 0 2 Voltage Input High 2 Vin Except RESET Pin 0 6 Vppt 0 5 V Voltage Vu RESET Pin 0 9 Vp O Von 0 5 V Voltage Output Low OHA 60 Ts Voltage Io 10mA Vpp 0 5 V Output High 20mA Vpp 5V 4 2 V Voltage Io 10mA Vpp 3V 22 Input Leakage 5 5V pin low 1 Current absolute value Input Leakage 5 5V pin high n Current ab
3. SPAI RESET SPAD RXD we we WPROT we RATESELECTO we AATESELECTI we BOARDID3 XTAL2 BOARDIDZ XTALI BOARDID1 vss BOARDIDO 3 1 3 TQFP User s Manual SPAS SPH RESET AAD NC TXD NC NC NC NC 3 2 Pin Descriptions of the Servo Control and Configuration pins are internally tied high through 20 50K pull up resistors The RESET pin 15 internally tied high through a 30 60K pull up resistor When used in the charts below logic levels 1 and 0 correspond to Vpp and Vss respectively SPAO0 7 These pins should be connected to the signal pin of servos 0 7 e SPBO 7 These pins should be connected to the signal pin of servos 8 15 e RESET This pin will reset the ServoCenter Chip when it is pulled low Use of a reset circuit will prevent unwanted chip resetting during power source fluctuation but such a circuit is not necessary for the operation of the chip e RXD amp TXD The RXD TXD pins can be used for serial communication between the ServoCenter Chip and another device This communication should follow the ServoCenter Protocol Vdo Vpp should be connected to a voltage in the range 2 7V 5 5V 5V is the nominal voltage e Vss Vss should be connected to the circuit s ground path User s Manual e RATESELECTO RATESELECTI These two pins determine the Data Rate for serial BOARDID0 BOARDID3 These 4 pins determine the Chip ID See char
4. The ServoCenter 3 1 Chip requires an 8 MHz clock signal for timing purposes The two circuits below are examples of how to generate this clock signal 5 5 1 Using a Crystal as a Clock Source In the following example an 8 MHz crystal 1s used as a clock source for the ServoCenter Chip Crystal Circuit Clock Input Pins Package XTALI Pin XTAL2 Pin PDIP 19 18 TQFP 15 14 PLCC 21 20 17 User s Manual 5 5 1 Using an Oscillator as a Clock Source In the following example an 8 MHz oscillator 15 used as the clock source for ServoCenter Chip Oscillator Circuit Clock Input Pins Package XTALI Pin XTAL2 Pin PDIP 19 18 15 14 PLCC 21 20 18 User s Manual 5 6 Setting the Board ID The following circuit shows how to interface a DIP switch to the BOARDID ID BOARDID pins The use of a DIP switch allows the BOARDID to be easily configured See Section 2 2 for more information Switch Selectable Board ID Board ID Pins Package BOARDID0 BOARDID1 Pins PDIP 21 24 TQFP 18 21 PLCC 24 27 19 User s Manual 5 Setting the Baud Rate The above circuit shows how to interface a DIP switch to the RATESELECT DR RATESELECT pins The use of a DIP switch allows the data rate to be easily configured See Section 2 2 for more information Switch Selectable Rate SHZ 3
5. TM pd ERIS 23 DEI 24 5 1 The Values 31 7 ServoCenter 3 1 Chip Sample 1 1 32 User s Manual 1 Introduction The ServoCenter Chip is a microcontroller that allows any serial communications capable device to control standard hobby servo motors The chip provides easy control of the seek position and seek speed of each of up to sixteen connected servos independently and simultaneously This independent control scheme allows one servo to be moving to a position slowly while another is moving to a different position quickly while yet another 15 moving to another position at a medium speed The ServoCenter Chip also offers advanced control features such as absolute amp relative control command sets raw amp scaled positional modes a simple yet reliable command protocol and on board settings storage The ability to independently control both position and speed combined with the controller s flexible and extensible feature set make the ServoCenter Chip especially useful for servo control applications such as robotics animatronics motion control automation retail displays and other areas where independent or coordinated fluid servo motion is necessary or desirable Up to 16 motors can be connected to each ServoCenter Chip and with proper support circuit
6. may have to be tweaked to get a full servo motion range out of all raw position modes The PwValue is measured in 10 microsecond units thus allowing the chip to produce any range of pulses in the range from 10 to 2390 microseconds Function Servo Invert Command Value 24 0x18 Data Bytes 1 Data Format SvNum 0 15 Description The Servo Invert command causes the servo channel specified by the first data byte SvNum to have its positions seek in an inverted manner This means that a raw position value of zero is the servo s extreme counter clockwise rotational position and 200 is the extreme clockwise position This function can be useful for dealing with paired servos or with servos that are mounted in such a way that an inverted positional system is more natural 29 User s Manual Function Servo Normal UnInvert Command Value 25 0x19 Data Bytes 1 Data Format SvNum 0 15 Description The Servo Normal command causes the servo channel specified by the first data byte SvNum to have its positions seek in the normal non inverted manner This means that a raw position value of zero is the servo s extreme clockwise rotational position and 200 is the extreme counter clockwise position Function Show Settings Command Value 235 Oxeb Data Bytes 0 Data Format None Description The Show Settings command causes the chi
7. specified by SvMaxSpeed and measured in centi seconds per 60 of travel that is allowed for a particular servo channel specified by SvNum This maximum speed is used to calculate all speed related seek commands Different servos have different rated travel speeds depending upon the manufacturer model and power supply voltage These speeds are generally rated in seconds per 60 of travel so the programmer will have to convert the rated speed in seconds to centi seconds by multiplying by 100 The ServoCenter 3 1 controller allows the maximum allowable travel speed to be set independently for each of the 16 servo channels Function Set Minimum to Current Command Value 8 0x08 Data Bytes 1 Data Format SvNum 0 15 Description The Set Minimum to Current command sets the minimum raw servo position set point to the current raw position of the servo of the specified servo specified by SvNum This minimum position is used in all scaled movement modes of operation Setting the minimum position above the start position will cause the start position to be set equal to the minimum Setting the minimum position above the maximum will cause the maximum position to be set equal to the minimum 23 User s Manual Function Set Maximum to Current Command Value 9 0x09 Data Bytes 1 Data Format SvNum 0 15 Description The Set Maximum to
8. 1 Data Format SvNum 0 15 Description The Get Min Position command causes the ServoCenter board to transmit a one byte message corresponding to the currently set minimum servo position of a particular servo specified by SvNum The ability of the chip to send these responses is partially dependent upon the wiring of the communications circuitry 26 User s Manual Function Get Max Position Command Value 13 0x0d Data Bytes 1 Data Format SvNum 0 15 Description The Get Max Position command causes the ServoCenter board to transmit a one byte message corresponding to the currently set maximum servo position of a particular servo specified by SvNum The ability of the chip to send these responses 15 partially dependent upon the wiring of the communications circuitry Function Get Start Position Command Value 14 0x0e Data Bytes 1 Data Format SvNum 0 15 Description The Get Start Position command causes the ServoCenter board to transmit a one byte message corresponding to the currently set starting servo position of a particular servo specified by SvNum The ability of the chip to send these responses 15 partially dependent upon the wiring of the communications circuitry Function Get Max Speed Command Value 15 0xOf Data Bytes 1 Data Format SvNum 0 15 Description The Get Max Spe
9. 32 Serial Communications The ServoCenter Chip can communicate with RS 232 capable devices via a level shifter and appropriate support circuitry The MAX232 in the example circuit shifts 12V RS 232 logic signals down to the 5V logic signals used by the ServoCenter Chip and shifts ServoCenter Chip logic signals up to RS 232 logic signals For more information about the MAX232 consult its data sheet 05232 Communications Circuit TLIN TLOUT 2 T2DUT RIOUT RAIN R20UT RIN 232 DBSFEMALE Serial Communication Pins Package TXD Pin RXD Pin PDIP 11 10 7 5 PLCC 11 13 13 User s Manual 5 3 2 TTL Serial Communications The ServoCenter Chip can communicate with serial controller devices at TTL signal levels This can be accomplished by simply connecting the RXD and TXD pins of the ServoCenter chip to the TX and RX pins of the controlling device Multiple ServoCenter Chips can receive commands from the same controller device by simply chaining the TX and RX lines together as shown here Non R8232 Communication ServoCenter 1 TTL Device Serial Communication Pins Package TXD Pin RXD Pin PDIP 11 10 7 5 PLCC 11 13 14 User s Manual 5 4 Powering The Servos In addition to providing power to the ServoCenter Chip itself the servos being controlled need must be powered The servos can be powered by a batte
10. Current command sets the maximum raw servo position set point to the current raw position of the specified servo specified by SvNum This maximum position is used in all scaled movement modes of operation Setting the maximum position below the start position will cause the start position to be set equal to the maximum Setting the maximum position below the minimum will cause the minimum position to be set equal to the maximum Function Set Start to Current Command Value 10 0x0a Data Bytes 1 Data Format SvNum 0 15 Description The Set Start to Current command sets the startup raw servo position set point to the current raw position of the specified servo specified by SvNum The start position is the position that the servo will assume when the system 15 powered up or reset The start position is capped and cannot be set greater than the maximum or less than the minimum Function Get Current Position Command Value 11 0xOb Data Bytes 1 Data Format SvNum 0 15 Description The Get Current Position command causes the ServoCenter board to transmit a one byte message corresponding to the raw servo position of a particular servo specified by SvNum The ability of the board to send these responses is partially dependent upon the jumper settings of jumper block 1 1 see section 3 4 1 of the user s manual for details Function Get Min Position Command Value 12 0x0c Data Bytes
11. T Vim M 12 Communica oS sencis D 13 5 51 2 32 COMMUNIC AIONS scu den boo toe D te 13 2 3 2 Sertab COMMUNICA TOTIS erue a 14 SA ENC SEV OS nada 15 5 4 Connecting ETT TU T UT UL LT IL 16 SE CLOCK rau UT 17 5 5 1 Using a Crystal as a Clock 17 5 5 1 Using an Oscillator as Clock 18 Setting Board E E EUa 19 5 7 settine the Baud 20 6 Programming ServoCenter 3 1 Chip Lecce eee ee eee eee eee eee eerte 21 01 servoCenter 5 T Protocol eie ta ee edge eo oae e EE vb Do eve dI 21 1 1 Protocol Oy Give Wegen aesti aedes An eben in pneri iin tette ees ae 21 CLZ NON Oy 22 D LO Siar Ol PAC 22 6 14 Command eas 23 Command DUMI y a en
12. The purpose of the checksum is to minimize the chances of the ServoCenter 3 1 chip receiving and acting upon corrupted or erroneous control messages In most instances the checksum should be used to enhance the reliability and robustness of the control system but as noted above a zero value can be placed in the checksum byte position to ignore the checksum calculation This placing of a 0 value in the checksum position can free the sender from having to worry about calculating the actual checksum This is useful in situations where simplicity of implementation is necessary and reliable communication is not a requirement 3l User s Manual 7 ServoCenter 3 1 Chip Sample Schematic Sample ServoCenter Implementation gt au 0 POWERCONNECTOR rur BAR PIN EXTPWR n Power 4 4 9 ye LM10B4IT ADJ D UDD 4 7k SPAL fut p m rm Reset 18pf 18pf PBL PB2 PB3 PB4 GPBb PB7 USS 1755 WPROT RATESELECTL RATESELECT2 BOARDID BOARDID2 BOARDIDS BOARDID4 Lt TUN TxD 24 TON RXD SK ROUT RAIN SERUDCENTERCHID34 J R20UT MAX232 7 DBSFENALE Note The pin numbers used in this schematic correspond to those of the PLCC package 32
13. User s Manual ServoCenter 3 1 Chip User s Manual amp Programming Guide Yost Engineering Inc 630 Second Street Portsmouth Ohio 45662 www YostEngineering com 2002 2005 Yost Engineering Inc Printed in USA User s Manual Table of Contents U COLON oiii EDO eL ELS UO EU OU D EL DEI GOD 3 PA igcemc e T M OT 3 3 OVER VICW DTE TIT 4 SJ Chip Package Din Gr ais eee 4 SPRL err nce E ene 4 tu PLUIE 4 TOF 5 Dol Pin dli ET E m 5 segui ir eee C ORT 7 AMP WY ces casas 7 AERECO rr 7 ET LI 8 TOPP 9 2 10 2 2 1 Absolute Maximum RINI S o oco hatch orig ol coats 10 Be DS CAL AC Le MIR CENTER E eee is 10 5 ServoCenter 3 1 Chip Example Support Circultry cccccssssssccsssssscccsssscceeees 11 S LPoWEESUDDIN ouo ePi obo inea ioo aa 11 Del C
14. by ASvPosition at a particular speed specified by SvSpeed Function Move Raw CCW Counter Clockwise Command Value 18 0x12 Data Bytes 3 Data Format SvNum 0 15 ASvPosition 0 200 SvSpeed 1 100 Description The Move Raw CCW command is used to move a servo s position counter clockwise by a certain amount at a specified speed The move raw counter clockwise command moves a servo specified by SvNum clockwise by a certain number of units specified by ASvPosition at a particular speed specified by SvSpeed Function Move Scaled Command Value 19 0x13 Data Bytes 3 Data Format SvNum 0 15 SvPosition 0 100 SvSpeed 1 100 Description The Move Scaled command 15 used to move servo s position at a specified speed The move scaled command moves a servo specified by SvNum to a scaled position specified by SvPosition at a particular speed specified by SvSpeed Scaled movement modes use the set minimum and maximum points to determine the servo s position The scaled position value can be thought of as a percentage of the range from the minimum to the maximum Thus 0 15 the minimum 100 15 the maximum and 50 is the midpoint between the set minimum and maximum The specified speed is calculated as a percentage of the preset maximum servo speed for the specified servo channel Thus a speed of 50 is half as fast as a speed of 100 a speed of 1 is 1 100 as fast as a spee
15. d of 100 etc Function Move Scaled CW Clockwise Command Value 20 0x14 Data Bytes 3 Data Format SvNum 0 15 A SvPosition 0 100 SvSpeed 1 100 Description The Move Scaled CW command is used to move a 5 position clockwise at a specified speed The move scaled clockwise command moves a servo specified by SvNum clockwise by a certain percentage specified by A SvPosition at a particular speed specified by SvSpeed The percentage indicated by SvPosition byte is based upon a percentage of the distance between minimum position and the maximum position Thus a distance of 10 units would move the servo clockwise by a distance of 1 10 of the entire scaled travel range a distance of 1 unit would move servo by 1 100 of the entire scaled travel range etc 28 User s Manual Function Move Scaled CCW Counter Clockwise Command Value 21 0x15 Data Bytes 3 Data Format SvNum 0 15 A SvPosition 0 100 SvSpeed 1 100 Description The Move Scaled CCW command is used to move a servo s position counter clockwise at a specified speed The move scaled counter clockwise command moves a servo specified by SvNum counter clockwise by a certain percentage specified by A SvPosition at a particular speed specified by SvSpeed The percentage indicated by the SvPosition byte is based upon a percentage of t
16. d to return status information about the current settings and positions of connected servos It is important to note that although many ServoCenter 3 1 chips can be connected and controlled simultaneously by a single controller only one of the connected boards may be configured to send data back to the controlling system The transmit receive functionality 1s determined by the Chip Communications Circuit 2 User s Manual 6 1 2 Packet Overview Each packet is from 3 to 6 bytes length and 15 formatted as follows 240 0xF0 Chip ID Command ID Command Data Command Data Command Data Checksum Value First Byte Start of Packet Calculated by adding 240 to the desired chip ID Second Byte Command Value Selected from one of the possible control commands Command Data Command Parameters Varies from zero to three bytes depending upon the command specified in the second byte position See the table below for specific command data format and specification Last Byte Packet Checksum See the checksum description below for specific calculation information Typical ServoCenter 3 1 Command Packet 6 1 3 Start of Packet Byte Each command packet starts with a specific type of byte called the Start of Packet byte The Start of Packet byte serves two purposes to signify the start of a command packet and to identify the chip ID of the intended recipi
17. ed 1 100 Move Raw CCW 18 0x12 3 SvNum 0 15 ASvPosition 0 200 SvSpeed 1 100 Move Scaled 19 0x13 3 SvNum 0 15 SvPosition 0 100 SvSpeed 1 100 Move Scaled CW 20 0x14 3 SvNum 0 15 A SvPosition O 100 SvSpeed 1 100 Move Scaled CCW 21 0x15 3 SvNum 0 15 AvoeSvPosition 0 100 SvSpeed 1 100 Set Pulse Width Min 22 0x16 1 PwValue 1 239 in 10us units Set Pulse Width Max 23 0x17 1 PwValue 1 239 in 10us units Servo Reverse 24 0x18 1 SvNum 0 15 Servo Normal 25 0x19 1 SvNum 0 15 Show Settings 235 Oxeb 0 None Commit Settings 236 Oxec 0 None Load Factory Settings 237 Oxed 0 None Reset as Startup 238 Oxee 0 None Display Version 239 Oxef 0 None 23 User s Manual Command Details In the tables below you ll find a description of each of the ServoCenter commands and a brief explanation of how and where each command would be used Function QuickMove Command Value 0 0x00 Data Bytes 2 Data Format SvNum 0 15 SvPosition 0 200 Description The QuickMove command provides a method of instantly moving a single servo specified by SvNum to a specified raw position specified by SvPosition This function 1s useful when it is desired to move a servo to a position as fast as possible With QuickMove no servo position interpolation 15 performed and the control signal for that specified servo 1s immediately modified when
18. ed command causes the ServoCenter board to transmit a one byte message corresponding to the currently set maximum speed setting of a particular servo channel specified by SvNum The ability of the chip to send these responses 1s partially dependent upon the wiring of the communications circuitry Function Move Raw Command Value 16 0x10 Data Bytes 3 Data Format SvNum 0 15 SvPosition 0 200 SvSpeed 1 100 Description The Move Raw command is used to move a servo s position at a specified speed The move raw command moves a servo specified by SvNum to a raw position specified by SvPosition at a particular speed specified by SvSpeed Raw movement modes do not use the set minimum and maximum points to determine the servo s position The specified speed is calculated as a percentage of the preset maximum servo speed for the specified servo channel Thus a speed of 50 is half as fast as a speed of 100 a speed of 1 is 1 100 as fast as a speed of 100 etc 27 User s Manual Function Move Raw CW Clockwise Command Value 17 0x11 Data Bytes 3 Data Format SvNum 0 15 ASvPosition 0 200 SvSpeed 1 100 Description The Move Raw CW command is used to move a servo s position clockwise by a certain amount at a specified speed The move raw clockwise command moves a servo specified by SvNum clockwise by a certain number of units specified
19. ent This byte s value is calculated by adding 240 0 hex to the chip ID of the chip to which you are sending the command message Thus a byte value of 240 0xf0 hex would be used to send a message to the chip with ID 0 241 0 11 for chip ID 1 242 0x12 for chip ID 2 etc 27 User s Manual 6 1 4 Command Set Command Summary The table below summarizes the ServoCenter 3 1 command set Description Command Data Length Data Descriptions QuickMove 0 x00 2 SvNum 0 15 SvPosition 0 200 Scaled QuickMove 1 0x01 2 SvNum 0 15 SvPosition 0 100 Servo Enable 2 0x02 1 SvNum 0 15 Servo Disable 3 0x03 1 SvNum 0 15 Set Min 4 0x04 2 SvNum 0 15 SvPosition 0 200 Set Max 5 0x05 2 SvNum 0 15 SvPosition 0 200 Set Start 6 0x06 2 SvNum 0 15 SvPosition 0 200 Set Max Speed 7 0x07 2 SvNum 0 15 SvMaxSpeed 1 200 in centi secs 60 Set Min to Current 8 0x08 1 SvNum 0 15 Set Max to Current 9 0x09 1 SvNum 0 15 Set Start To Current 10 1 SvNum 0 15 Get Current Position 11 OxOb 1 SvNum 0 15 Get Min Position 12 Ox0c 1 SvNum 0 15 Get Max Position 13 0x0d 1 SvNum 0 15 Get Start Position 14 0x0e 1 SvNum 0 15 Get Max Speed 15 0 0 1 SvNum 0 15 Move Raw 16 0x10 3 SvNum 0 15 SvPosition 0 200 SvSpeed 1 100 Move Raw CW 17 Ox11 3 SvNum 0 15 ASvPosition 0 200 SvSpe
20. he distance between the minimum position and the maximum position Thus a distance of 10 units would move the servo clockwise by a distance of 1 10 of the entire scaled travel range a distance of 1 unit would move the servo by 1 100 of the entire scaled travel range etc Function Set Pulse Width Min Command Value 22 0x16 Data Bytes 1 Data Format PwValue 1 239 Description The Set Pulse Width Minimum command lets the user specify the minimum value of the range of control pulses that are produced by the ServoCenter 3 1 chip for all raw position modes This minimum value is applied globally to all servo channels of the chip Since some servos have slightly different control pulse width ranges this value may have to be tweaked to get a full servo motion range out of all raw position modes The PwValue is measured in 10 microsecond units thus allowing the chip to produce any range of pulses in the range from 10 to 2390 microseconds Function Set Pulse Width Max Command Value 23 0x17 Data Bytes 1 Data Format PwValue 1 239 Description The Set Pulse Width Maximum command lets the user specify the maximum value of the range of control pulses that are produced by the ServoCenter 3 1 chip for all raw position modes This maximum value is applied globally to all servo channels of the chip Since some servos have slightly different control pulse width ranges this value
21. hey were in when shipped as new This command only loads the settings and doesn t commit the settings to the EEPROM of the chip To restore the settings and save these settings the user should perform a Commit Settings command following the Load Factory Settings command 30 User s Manual Function Reset as Startup Command Value 238 Data Bytes 0 Data Format None Description The Reset as Startup command causes the chip to perform a software reset of the control software This command is functionally equivalent to resetting or cycling the power of the chip All EEPROM settings are loaded and all servo channels are modified according to these stored settings Function Display Version Command Value 239 Oxef Data Bytes 0 Data Format None Description The Display Version command simply displays the version of the firmware embedded within your ServoCenter 3 1 chip This can be useful for allowing software to query the chip s version to ensure interoperability between this and other future YEI products 6 1 5 The Checksum Value The checksum 15 computed as arithmetic summation of all of the characters in the packet except the checksum value itself modulus 239 plus one This gives a resulting checksum in the range 1 to 239 The checksum will be ignored if a 0 byte value is passed in the checksum position of the packet
22. osition to be set equal to the minimum Setting the minimum position above the maximum will cause the maximum position to be set equal to the minimum 24 User s Manual Function Set Maximum Command Value 5 0x05 Data Bytes 2 Data Format SvNum 0 15 SvPosition 0 200 Description The Set Maximum command sets the maximum raw servo position set point specified by SvPosition of the specified servo specified by SvNum This maximum position 15 used in all scaled movement modes of operation Setting the maximum position below the start position will cause the start position to be set equal to the maximum Setting the maximum position below the minimum will cause the minimum position to be set equal to the maximum Function Set Start Command Value 6 0x06 Data Bytes 2 Data Format SvNum 0 15 SvPosition 0 200 Description The Set Start command sets the starting raw servo position set point specified by SvPosition of the specified servo specified by SvNum The start position is the position that the servo will assume when the system is powered up or reset The start position is capped and cannot be set greater than the max or less than the min Function Set Maximum Speed Command Value 7 0x07 Data Bytes 2 Data Format SvNum 0 15 SvMaxSpeed 1 200 Description The Set Maximum Speed command sets the maximum speed as
23. p to transmit a table of the current settings for all channels The format of the returned data is a human readable table composed of ASCII characters This fuction is useful when troubleshooting a chip s settings or simply verifying current settings The ability of the chip to transmit these settings 1s partially dependent upon the wiring of the communications circuitry Function Commit Settings Command Value 236 Data Bytes 0 Data Format None Description The Commit Settings command causes the chip to save the current settings into the EEPROM storage Once the board s settings are stored in the EEPROM settings of the ServoCenter 3 1 they will be restored every time the chip is either reset or powered up This allows the configuration to be saved thus avoiding a configuration process every time chip 15 reset Note the EEPROM storage of the ServoCenter 3 1 chip has a limited lifetime of rewritability about 100 000 rewrites so avoid writing a programmatic loop that continuously commits the settings of the chip The current rewrite count can be viewed by using the Show Settings command A user can prevent chip settings from being written by connecting the WProt pin to GND Function Load Factory Settings Command Value 237 Oxed Data Bytes 0 Data Format None Description The Load Factory Settings command causes all of the chip s settings to revert to the state that t
24. ry up to 16 ServoCenter Chips can be daisy chained together thus allowing for a total of 256 RC servos to be controlled independently and simultaneously from one serial device 2 Features Standard RS 232 or TTL serial control at 9600 14400 19200 or 38400 bps Control position and speed of all connected servos simultaneously Scaled motion commands allow maximum minimum and startup position setting making complex motion programming easier Absolute and relative position commands allow for greater programming flexibility Configuration information saved even when the power 15 off Control up to 16 RC servos per chip Daisy chain up to 16 chips to control up to 256 servos from one serial controller Simple yet robust serial protocol makes programming simple Downloadable example code can get you started quickly Example programs available for VC6 VB6 QBASIC Turbo C and GCC LINUX User s Manual 3 Chip Overview 3 1 Chip Package Diagrams 3 1 1 PLCC T 1 spas 7 105773 SPAG SpA2 Spa SPAI RESET 1 seo RXD NC TXD 1 NC NC 30 1 wegRoT NC 29 RATESELECTO Pd OO Pd Cd D Cd Cd Cd 64 LT LI LI LI LI LI LJ U y i Ci m 55426558656 iiri 3 1 2 DIP vee SPAI Spar ETE SPAS spas 5 4 SPA4 SPA SPAS SPA2 Spa
25. ry or ant other regulated power source of sufficient amperage capability Servos will exhibit higher speed and torque at higher voltages Most servos will list the operating characteristics at 4 8V and 6V in their documentation LM1084IT ADJ is an example of an adjustable voltage regulator that can be used to accommodate a variety of voltage requirements Note that a voltage regulator 15 not necessary if batteries or a regulated power supply 15 being used Servo Power Circuit POWERCONNECTOR c EXTPWR1 Now L I1B84IT RDJ USERUO IN QUT ae C4 C2 R1 470 RSET 1Buf RSET USRUO 47 64 36B 4 80 In the LM1084IT circuit shown should be around 1000 to maintain an appropriate amount of feedback current The resistance of R2 should be changed to modify the output voltage of the regulator The Servo Supply Voltage of the LM1084IT ADJ can be determined by using the formula VSERVO 1 25 1 2 R1 R2 VServo 3600 4 8V 470Q 6V 15 User s Manual 5 4 Connecting The Servos Servo Ports A amp B provide the control signals for up to 16 servos If using separate power supplies for VSERVO and VDD remember to tie the grounds together Servo Connection Circuit VSERVO Servo Control Pins Package SPA Pins SPB Pins PDIP 32 39 1 8 TQFP 30 37 40 44 1 3 PLCC 36 43 2 9 16 User s Manual 5 5 Clock Signals
26. solute value Rest Reset Pull up 30 60 Resistor Rev Pull up 20 50 KO Resistor pu EOE URPI 12 mA Current Notes 1 means the highest value where the pin 1s guaranteed to be read as low 2 Min means the lowest value where the pin is guaranteed to be read as high 10 User s Manual 5 ServoCenter 3 1 Chip Example Support Circuitry 5 1 Power Supply Chip Vpp should be in the range 2 7 5 5V One way to achieve this voltage is through the use of a voltage regulator such as the LP2931CZ 5 0 EXTPWR should be at least 5V and not greater than the maximum rating of the voltage regulator 30V for the LP2931CZ 5 0 Chip Power Circuit TOR BAR LP2931C2 5 B E IM OUT GND Power Supply Pins Package VDD Pin VSS Pin PDIP 40 20 38 16 PLCC 44 22 11 User s Manual 5 2 Reset Circuit The ServoCenter Chip has an active low RESET input pin Pulling this RESET pin low will cause the ServoCenter Chip to reset Chip Reset Circuit RESET Pin Package RESET Pin PDIP 9 TQFP 4 PLCC 10 12 User s Manual 5 3 Serial Communications The ServoCenter Chip has an onboard UART which makes it very easy to implement serial communication The example circuits below are for RS 232 and TTL level communication 5 3 1 RS 2
27. t below BOARDIDO0 BOARDIDI BOARDID2 BOARDID3 Chip ID 1 1 1 1 0 0 1 1 1 1 1 0 1 1 2 0 0 1 1 3 1 1 0 1 4 0 1 0 1 5 1 0 0 1 6 0 0 0 1 7 1 1 1 0 8 0 1 1 0 9 1 0 1 0 10 0 0 1 0 11 1 1 0 0 12 0 1 0 0 13 1 0 0 0 14 0 0 0 0 15 communication See chart below RATESELECT0 RATESELECTI1 Data Rate 1 1 9600 0 1 14400 1 0 19200 0 0 38400 WPROT This is the Write Protection Pin To enable Write Protection tie WPROT to Vss XTAL1 XTAL2 For ServoCenter 3 1 Chip to operate correctly it must be interfaced to an 8 MHz clock signal This can be accomplished by either attaching an oscillator to XTALI and leaving XTAL2 hanging or by tying a crystal between XTAL I and XTAL2 User s Manual 4 Specifications 4 1 Physical 4 1 1 PLCC 1 14 0 045 X 45 1 14 0 045 X 45 PIN NO 1 0 318 0 0125 IDENTIFIER 0 191 0 0075 Fi E D2IE2 E a A2 D D l 0 51 0 020 45 3X B COMMON DIMENSIONS LL Unit of Measure mm uso ux wi Dior Lx pm _ Lu pme we _ we wer uxe msn Notes 1 This package conforms to JEDEC reference MS 018 Variation AC 2 Dimensions D1 and E1 do not include mold protrusion 16 510 EN IDEE Allo
28. the command is issued Function Servo Enable Command Value 2 0x02 Data Bytes 1 Data Format SvNum 0 15 Description The Servo Enable command provides a method of enabling a servo specified by SvNum This function is used to enabled a servo channel that has been previously disabled With the control signal enabled the servo will actively hold its position Enabled servos will draw significantly more power than disabled servos Function Servo Disable Command Value 3 0x03 Data Bytes 1 Data Format SvNum 0 15 Description The Servo Disable command provides a method of disabling a servo specified by SvNum This function is used to remove the control signal for a servo channel With the control signal disabled the servo will not actively hold its position This can be useful for disabling a servo without having to physically disconnect it from the chip A disabled servo can generally be moved by hand and will draw significantly less power than an enabled servo Function Set Minimum Command Value 4 0x04 Data Bytes 2 Data Format SvNum 0 15 SvPosition 0 200 Description The Set Minimum command sets the minimum raw servo position set point specified by SvPosition of the specified servo specified by SvNum This minimum position 15 used in all scaled movement modes of operation Setting the minimum position above the start position will cause the start p
29. wable protrusion is 010 0 254 mm per side Dimension 01 DF 14 286 16 002 and E1 include mold mismatch and are measured at the extreme material condition at the upper or lower parting lina EN iiis EN ial MN 3 Lead coplanarity is 0 004 0 102 mm maximum 030 0533 1 270 TYP User s Manual 4 1 2 PDIP SEATING PLANE ie COMMON DIMENSIONS 00 150 REF Unit of Measure 1 svmeoL MN Now MAX NOTE Uu sum us ce _ tm wer B ju os Notes 1 This package conforms to JEDEC reference 5 011 Variation AC mot is 2 Dimensions D and E1 do not include mold Flash or Protrusion i aas Mold Flash or Protrusion shall not exceed 0 25 mm 0 0107 EN 2 540 User s Manual 4 1 3 TQFP PIN 1 PIN 1 IDENTIFIER Notes 1 This package conforms to JEDEC reference MS 026 Variation ACB 2 Dimensions D1 and do not include mold protrusion Allowable protrusion is 0 25 mm per side Dimensions D1 and 1 are maximum plastic body size dimensions including mold mismatch 3 Lead coplanarity 15 0 10 mm maximum COMMON DIMENSIONS Unit of Measure mm Ten an rs eas Pew ce ow Ce aw ce foe
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