Cerebellum User`s Manual (draft), PDF format
Contents
1. The download program will inform the user of its successful completion Once the serial user interface firmware has been downloaded the board is ready for use To boot up the Cerebellum connect up the power and serial connectors and switch the power switch to its ON position The indicator LED on the upper left hand corner PWRLED should light up Remember to disconnect the programming connector CON3 Serial User Interface The Cerebellum uses the SER2 serial port for communications with a host computer This port can operate at baud rates of 9600 19200 or 38400bps The default speed is 38400bps Communications parameters are as follows e 8 data bits No parity bit 1 STOP bit e No flow control Running a serial terminal program on the host computer while turning on the Cerebellum should give the following boot up message from the microcontroller Cerebellum Serial Interface v0 9 22 Aug 01 OK This shows that the firmware has been downloaded properly and serial communications are working The Cerebellum should now respond to commands sent to it over this serial link As a further check the Cerebellum should echo all characters that it receives so the local echo option on the PC s terminal program should be turned off Serial Command Set All received commands will be converted into uppercase before processing so command processor becomes case insensitive Whitespace is optional where other separators and delimite2. of the motor defaults to if unspecified Returns OK r Command completed ERROR r Error parsing command Examples MT1 100 r motor 1 forward speed 100 MT 250 50 r motor O forward speed 250 motor 1 reverse speed 50 DBn d r Daughterboard command n is the number of a specific daughterboard valid values from 0 to 7 inclusive d is a data byte that is to be sent to the daughterboard in decimal form 0 to 255 inclusive Response packet will only be read from daughterboard if data bytes are sent Returns lt daughterboard response gt r OK r Command completed NACK r NACK received during I2C transmission ERROR r Error parsing command Examples DB3 15 27 230 O r open i2c communications to daughterboard 3 sends data bytes 15 27 230 0 DBO r checks for presence of daughterboard 0 returns OK if daughterboard ACKs address byte that was transmitted over I2C NACK if no daughterboard responds to address 0 SS foo Rn r Sends command to the camera using the secondary serial port The R option specifies the number of Nr delimited lines to echo from camera output n can range from to 255 inclusive Camera output is echoed completely including the Nr character No camera output is echoed if no R option is present There is a timeout value between receiving consecutive bytes from the camera Returns OK r Read from camera output completed TIMEOUT r Timeout while waiting for camera
3. output ERROR r Error parsing command Examples SS too send command foo to camera no camera output read SS b a r R4 send command b a r to camera read 4 lines of output SSR1 read 1 line of output from camera TO n lr Set or show camera output timeout being the maximum idle time between 2 consecutive bytes of camera output n is the timeout value in 10s of milliseconds ranging from 0 to 255 inclusive and takes effect immediately It will be stored into EEPROM and still be in effect after a reset A value of 0 would indicate an infinite timeout If n is not specified returns the current timeout value Returns OK r Command completed timeout value set 0 255 r OK r Current timeout value in ms ERROR r Error parsing command 10 ANn r Read from analog input port n is the number of the analog input valid values from 0 to 7 inclusive Returns EO 42005 AE OK r Digitized analog value ERROR r Error parsing command The diagram below shows how a potentiometer can be connected to CONI as an input device to analog port 0 1Okohm Din r Read from digital input port n is the number of the digital input valid values from 0 to 7 inclusive Will configure the specified I O pin as an input if it is not already so Returns O r OK r Binary logic value INE OK r Binary logic value ERROR r Error parsing command 11 DHn r Output high from digital output port n is the number of th
4. Personal Rover Project Cerebellum Board User s Manual Revision date 1 29 02 Introduction The Cerebellum is intended as the main controller board for the Personal Rover Built around PIC microcontroller it provides the following functionality e Controls up to 8 hobby servos e Open loop control of 2 DC motors e Read from up to 8 analog input lines at 8 bit resolution e 4 digital I O lines e 2RS232 serial communications ports e DC bus master for up to 8 motor controller daughterboards e ASCTI based serial user interface e User programmable over PC parallel port Hardware The following is a list of the main parts that are needed for assembling the Cerebellum Quantity Part no Digikey unless specified 1 Cerebellum printed circuit board PIC16F877 20 P ND AX232CPE ND Allegro UDN2998 OF 1716 Newark M2940CT 5 0 ND ECS ZTT 20MHz crystal resonator 909 ND 4400 ND 138 ND 105 ND 966 ND luF ceramic capacitor 924 ND 7pF ceramic capacitor 845 ND i oO x EN SEE O wo A E TKQBK ND 50 1365 ND N OQBK ND 3 SPST switch 1847 ND 40 pin DIP socket 3640 ND 16 pin DIP socket S J 3316 ND z i 2700 ND M2701 ND 29400 01 36 ND 29836 09 36 ND Dual row female headers 29975 01 36 ND No Quantity ES E EE EE The PCB layout diagram can be found in Appendix A Power The Cerebellum has a voltage regulator that provides a stable 5V to it
5. e digital input valid values from 0 to 7 inclusive Will configure the specified I O pin as an output if it is not already so Returns OK r Command completed ERROR r Error parsing command DLn r Output low from digital output port n is the number of the digital input valid values from 0 to 7 inclusive Will configure the specified I O pin as an output if it is not already so Returns OK r Command completed ERROR r Error parsing command 12 BR lt 9600 19200 38400 gt r Sets baud rate of PC serial communications port SER2 New baud rate will be stored into EEPROM and will only take effect after a reset Returns OK r Command completed ERROR r Error parsing command VER r Dis plays cerebellum firmware version number Returns Cerebellum Serial Interface vl 0 r OK r Command completed 13 Appendix A O OPOZAN ZuMd Ei O 8 ZHINOG IX O con JUL oS APAPA rO X R 14 15
6. gher if the H bridge was drawing its power from the primary input instead of from its own auxiliary power input In this case the voltage supplied to the primary input should be however much the DC motors require Serial ports The SER1 connector is used to connect the Cerebellum to the camera module SERI pin number Purpose 1 Camera receive PIC transmit 2 Camera transmit PIC receive 3 Ground The SER2 connector is used for RS232 serial communications with a host PC The diagram below shows the wiring required to connect the SER2 serial port on the Cerebellum to a DB 9 connector on a serial cable PC receive PIC transmit PC transmit PIC receive Ground Connecting hobby servos The following diagram shows the pin numberings for the bank of 8 servo motor connectors The cable colors correspond to those found on standard Futaba hobby servos Each connector from SVO to SV7 can be connected to one hobby servo giving a total of 8 servos SV 0 7 pin number Purpose PWM control signal Positive power supply Ground LV T O connector CONI is the auxiliary I O connector It contains the Cerebellum s analog input and digital I O lines It also provides power supply pins for these additional circuits The diagram below shows the pin numbering order for CON1 The pins are numbered such that odd numbered pins are below and even numbered pins are above 5V regulated PWR unregulated Analog input ports Gr
7. ound Digital I O ports CONI pin number Purpose 1 2 Positive power supply from PWRI unregulated 3 Ground 4 5V regulated 5 Analog input port 0 6 Analog input port 1 7 Analog input port 2 8 Analog input port 3 9 Analog input port 4 10 Analog input port 5 11 Analog input port 6 12 Analog input port 7 13 Digital I O port 0 14 Digital I O port 1 15 Digital I O port 2 16 Digital I O port 3 PC connector The diagram below shows the pin numbering order for CON2 the I2C bus connector CON2 pin number Purpose 1 PWR 2 GND 3 PC clock line SCK 4 PC data line SDA Programming connector The following diagram shows the wiring necessary for connecting the programming connector CON3 to the 25 pin connector of a PC s parallel port POGOoOO OOOO 6 6 CON3 pin number DB25 pin number Purpose Ground Programming Data In Programming Clock Memory Clear Reset Enter Low Voltage Programming Mode Programming Data Out Not connected o IAN EUR Not connected Software Once the board has been assembled and powered up firmware can be downloaded onto the microcontroller Both firmware HEX file and downloader DLPIC can be downloaded from http www cs cmu edu myrover cerebellum software If the files have been downloaded into the c cerebellum directory the following command downloads the HEX file SUI HEX onto the PIC C CEREBELLUM gt dlpic sui hex
8. rs already exist Where one space can exist multiple spaces will also be accepted All commands shall be terminated by a carriage return character r ASCII 13 All commands will return OK r ERROR r or TIMEOUT r as their final status and no further user input will be read until then Upon reset the current firmware version and EEPROM settings will be displayed Typing r at the beginning of a line will display a command summary SV n m m r Hobby servo command n is the number of a specific servo and can range from 0 to 7 inclusive m from 0 to 255 inclusive Maximum of 8 servo movement parameters A or prefix will cause m to be interpreted as a relative increment or decrement from the servo s current position Position O disables the particular servo position 128 being the servo s center position At startup all servos are disabled Returns OK r Commmand completed ERROR r Error parsing command Examples SV5 30 r Servo 5 to position 30 SVO 10 r Servo 0 increment by 10 SV7 67 r Servo 7 decrement by 67 SV 5 4 12 r Servo 0 to position 5 servo 1 increment 4 servo 2 decrement 12 SV 000 0 15 27 2 50 r Servos 0 thru 3 disable servo 4 increment 15 5 decrement 27 6 increment 2 7 position 50 MT n m m r DC motor control n is the number of a DC motor 0 or 1 mis PWM duty cycle 0 being off 255 begin 100 The or prefix controls the direction
9. s logic systems and integrated circuits This means that more than 5V has to be supplied to the primary power input to provide for the dropout voltage of the regulator Both the H bridge and the hobby servos can be powered through either the main power supply or their own independent power supplies This is selected using jumpers on JP1 and JP2 respectively The following diagrams and tables show the pin numbering and appropriate jumper connections for JP1 JP2 PWR1 PWR2 and PWR3 dE Pwr EO 2 PWRI pin number JP1 connections Pins 1 amp 2 Pins 2 amp 3 PWR2 pin number JP2 connections Pins 1 amp 2 Pins 2 amp 3 PWR3 pin number Connection Positive power Ground Function DC motors draw power from PWR1 DC motors draw power from PWR2 Connection Positive H bridge power Ground Function Hobby servos draw power from PWR1 Hobby servos draw power from PWR3 Connection Ground Positive hobby servo power The voltage supplied to the primary power input should be at least 6V to supply regulated power to the various ICs Preferably 8 12V should be supplied so that voltage regulation can be maintained during spikes and transients caused by motors There is a limit of 25V imposed by the specifications of the voltage regulator A higher supply voltage is required if you re using a regular voltage regulator eg 78LS05 instead of a low dropout regulator LM2940 It should also be hi
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