DE2Bot User`s Manual Georgia Institute of Technology ECE2031
Contents
1. Init Always a good idea to make sure the robot stops in the event of a reset LOAD Zero OUT LVELCMD Stop motors OUT RVELCMD OUT SONAREN Disable sonar optional CALL SetupI2c Configure the I2C to read the battery voltage CALL BattCheck Get battery voltage and end if too low OUT LCD Display batt voltage on LCD WaitForSafety Wait for safety switch to be toggled IN XIO XIO contains SAFETY signal AND Mask4 SAFETY signal is bit 4 JPOS WaitForUser If ready jump to wait for PB3 IN TIMER We ll use the timer value to AND Mask1l blink LED17 as a reminder to toggle SW17 SHIFT 8 Shift over to LED17 OUT XLEDS LED17 blinks at 2 5Hz 10Hz 4 JUMP WaitForSafety WaitForUser Wait for user to press PB3 IN TIMER We ll blink the LEDs above PB3 AND Mask1l SHEETS 5 Both LEDG6 and LEDG7 STORE Temp overkill but looks nice SHIFT 1 OR Temp OUT XLEDS IN XIO XIO contains KEYs AND Mask2 KEY3 mask KEYO is reset and can t be read JPOS WaitForUser not ready KEYS are active low hence JPOS LOAD Zero OUT XLEDS Clear LEDs KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KK KKK KKK KKK KK KKK KKK KEK Main code KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKKKKKKK r reset odometry in case wheels moved after programming this example Main Real program starts here OUT RESETODO JUMP Main Die does nothing So2. 13 0V is dead e The battery level is displayed as a bar graph on red LEDs 0 14 o A fully charged battery will light all LEDs 0 14 A dead battery will light only LED O e Green LEDs O 1 and 2 light mirroring the inactive state of pushbuttons 1 2 and 3 respectively o Pressing a PB will turn off the respective green LED e The LCD displays a menu prompting the user to choose Self Test or Troubleshoot Power up Errors If the battery is too low to safely operate the DE2Bot the user is warned with beeps flashes and a written warning on the LCD In this case turn off the DE2Bot immediately and plug it in to a charger If nothing happens when the DE2Bot is turned on there is likely a problem with the battery or power circuitry Turn the DE2Bot switch to the OFF position and notify an administrator Automated Self test At the LCD prompt after power up pressing PB1 will begin a mostly automated self test routine The LCD will provide prompts that allow the user to execute the automated self test without this document but detailed information is provided here for first time users or in the case of errors 1 Battery Check The battery voltage is tested and displayed in decimal on the LCD screen Battery voltage should be 13 17V for proper robot operation 2 Sonar Test Each of the eight sonar sensors is tested starting with Sonaro left facing sonar and proceeding clockwise Each sonar is polled until either a vali
3. EQU amp HAB DIST4 EQU amp HAC DIST5 EQU amp HAD DIST6 EQU amp HAE DIST7 EQU amp HAF SONAREN EQU amp HB2 register to control which sonars are enabled XPOS EQU amp HCO Current X position read only YPOS EQU amp HC1 Y position THETA EQU amp HC2 Current rotational position of robot 0 701 RESETODO EQU amp HC3 write anything here to reset odometry to 0
4. can be used to keep track of wheel rotation and calculate angular position velocity and acceleration The addition of specialized hardware can enable dead reckoning estimation of robot position The control circuitry for the motors includes a watchdog timer that disables the motors if no alive signal is received for approximately one second In the default Quartus project for ECE2031 an additional safety mechanism disables the motors until SW17 has been toggled both up and down after power up or reset This is to ensure that the robot does not move immediately after being programmed and guarantees that the robot will stop when PBO is pressed Sonar Distance Sensors The DE2Bot is equipped with eight sonar transducers that can be used to measure distances to objects The sensors are arranged around the robot as shown in Figure 2 and numbered clockwise starting with Sonar 0 which is facing left from the robots forward orientation downwards in the figure Figure 2 Sonar sensor numbering positions and directions The sonar sensors can measure distances from 15cm up to 5m or more depending on the reflectivity of the object The resolution of the measurement is dependent on the sampling speed of the interfacing hardware the default resolution of the DE2Bot hardware is 1mm Note that this does not imply 1mm accuracy though within 5mm can be expected Each sonar sensor can be enabled independently The sonar firing rate is 20Hz di
5. DE2Bot User s Manual Georgia Institute of Technology ECE2031 Introduction This document is intended for the end user of the DE2Bot students in ECE2031 It provides an overview of the hardware a walkthrough of the built in self test program and a programming guide for use with the version of SCOMP provided during the final design project Table of Contents DE2ZBot HatdwareOvervi QW vig ssi cripian Te SaRaNa EESE aaa AEEA aa Eaa aaaea eiaa 3 Feature DESCHIPU ONS serura n E e a a a a ETa 4 Sek test Operas ON orcas esn EE EE E E EE LE 6 POWEr UP D K EC KeS E a EEE E E E E E E T A E E 6 Automated Self test icsse ikuinen iaaiiai ia aia aa aa ia aa aaa aie aaka 6 Manual TEStS ssis cin stetccc seis ccevanacd act oi bees e a aea aa e aa eiai aaa aa aiea 7 Programming GUIDE enirar nrar anaE EE OEE ROAR EO AEE RO ORE 9 Changes to SCOM P ic csaccatscchcassiesase iphone ai a Ea R Rai 9 SCOMP Interrupt Syste Mi sss iveseie taenn aa A NEEE E bos EAE EAE EE E EEEE AAEE 9 IO Device Quick Reference siiin aa e aa e a a E E a ets nceeiee 10 Detailed Description of Select D VICOS ccccccccsssssssscecececesseseaeseeececesseseeaeeesecesssesaeaeeeeeceseesesaeaeceeecesseseaeaeeeeeens 11 Wheel Position Velocity and Velocity COMMANAS c ccccsesseeceeseneeceeseeeceeceeeececeeeeeceeeeneeesseeeaeesseeaaeeeseenaeess 11 SOMA SEMSOMS E PE A E A E ence depanen 204s O E avebede aude ees ubacegyyteoeters omncecepenen 11 FC Controller and Battery Voltage a
6. KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK r IO address space map ekkxkxkxkxkxk xkxk xk xkxk xkxkxk xkxk xkxkxk xkxkxk xkxkxkxkxkxkxkxkxkxk xkxkxkxkxk xkxkxk xkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkkxxk kxx k LA SWITCHES EQU amp HOO slide switches LEDS EQU amp H01 red LEDs TIMER EQU amp HO2 timer usually running at 10 Hz XIO EQU amp HO3 pushbuttons and some misc inputs SSEG1 EQU amp HO4 seven segment display 4 digits only SSEG2 EQU amp HO5 seven segment display 4 digits only LCD EQU amp HO6 primitive 4 digit LCD display XLEDS EQU amp HO7 Green LEDs and Red LED16 17 BEEP EQU amp HOA Control the beep LPOS EQU amp H80 left wheel encoder position read only VEL EQU amp H82 current left wheel velocity read only iVELCMD EQU amp H83 left wheel velocity command write only RPOS EQU amp H88 same values for right wheel RVEL EQU amp H8A_ RVELCMD EQU amp H8B I2C_CMD EQU amp H90 I2C module s CMD register I2C_ DATA EQU amp H91 DATA register I2C_RDY EQU amp H92 and BUSY register UART DAT EQU amp H98 UART data UART RDY EQU amp H98 UART status SONAR EQU amp HAO base address for more than 16 registers DISTO EQU amp HA8 the eight sonar distance readings DESTI EQU amp HA9 DIST2 EQU amp HAA DTST 3s
7. Velocity Commands The values read from LPOS and RPOS provide the wheel encoder counts since reset The encoders provide 304 ticks revolution which corresponds to linear movement of approximately 1 05mm count for LPOS and RPOS LVEL and RVEL provide approximations of wheel velocity by sampling the position every 0 1s and providing the difference x10 the units are thus approximately 1 05mm s LVELCMD and RVELCMD accept values in the same units as LVEL and RVEL and attempt to control the wheel velocities to match that value Be aware that very low speeds usually lt 50mm s may not be able to overcome the static friction of the motors gearboxes axles and wheels and so may not result in any movement However once moving the lower bits of LVELCMD and RVELCMD do provide additional resolution to the speed The values sent to LVELCMD and RVELCMD should not exceed 511 If a value outside that range is provided the motor controller will interpret it as O stopped The acceleration including deceleration of each wheel is fixed at 512units s thus if the robot is moving at velocity v in robot units and is commanded to stop by sending 0 to LVELCMD and RVELCMD the expected overshoot can be estimated by v 1024 the result of which is again in robot units of 1 05mm Sonar Sensors Each sonar can be independently enabled through the SONAREN register Bits 0 7 of this register correspond to sonars 0 7 e g writing Ob00000001 will enable o
8. d reading is obtained or 5 seconds elapse If the test pauses on a particular sonar move an object such as your hand in front of that sonar so that a reading can be obtained The current sonar is indicated on the red LEDs or you can listen for the characteristic clicking sound Once all sonar sensors are tested and working the message All sonars are working is displayed on the LCD and the program automatically proceeds to the next test Sonar Errors If a sonar does not return a valid reading within 5 seconds it is assumed to be defective At the end of the sonar test the green LEDs display which sonar s are not working Note the number s and return the DE2Bot to an administrator 3 Encoder Test Warning The test immediately following this test will cause the robot to move under its own power Ensure that the DE2Bot is either on the floor in a clear area or its wheels are raised off of the supporting surface Continuing this test with the robot on a table can cause it to fall when the following test begins Once the sonar test is complete the LCD will display Rotate left wheel 30 degrees At this prompt manually rotate the left wheel in either direction until the LCD changes to Rotate right wheel 30 degrees then repeat the rotation with the right wheel During this test the current encoder position value is displayed on HEX3 0 Encoder Errors If no wheel motion is detected within 10 seconds the te
9. from writing to these KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKKKK NegOne Zero One Two Three Four Five Six Seven Eight Nine Ten DW DW DW DW DW DW DW DW DW DW DW DW l j FPOoOWAATIAOABWNEF CO Some bit masks Masks of multiple bits can be constructed by ORing these l bit masks together k0 k1 k2 k3 k4 k5 k6 k7 Mas Mas Mas Mas Mas Mas Mas Mas DW DW DW DW DW DW DW DW amp B00000001 amp B00000010 amp B00000100 amp B00001000 amp B00010000 amp B00100000 amp B01000000 amp B10000000 LowByte DW amp HFF binary 00000000 1111111 LowNibl DW amp HF 7 0000 0000 0000 1111 some useful movement values OneMeter DW 952 lm in 1 05mm units HalfMeter DW 476 0 5m in 1 05mm units TwoFeet DW 640 7 2ft in 1 05mm units Deg90 DW 176 90 degrees in odometry units Deg180 DW 351 7 180 Deg270 DW 527 7 270 Deg360 DW 702 can never actually happen for math only FSlow DW 100 100 is about the lowest velocity value that will move RSlow DW 100 FMid DW 350 350 is a medium speed RMid DW 350 FFast DW 500 500 is almost max speed 511 is max RFast DW 500 MinBatt DW 130 13 0V minimum safe battery voltage I2CwWCmd DW amp H1190 write one i2c byte read one byte addr 0x90 I2CRCmd DW amp H0190 write nothing read one byte addr 0x90 oe KKKKKKKKK
10. g is highly susceptible to accumulated error from wheel slippage wheel size and wheel base errors mathematical rounding and other sources The odometry values will likely contain significant error after as little as a few meters of travel or one rotation of the robot and much of the error will not be systematic XIO The value read from XIO contains the following signals e XIO 15 5 GPIO pins on the DE2 header e XIO 4 SAFETY signal which indicates whether or not SW17 has been toggled e XIO 3 SW16 e XIO 2 0 Pushbuttons PB3 PB1 PBO is global reset and cannot be read Note that the pushbuttons are active low a pressed pushbutton will appear as a 0 in XIO 12 Good Practices for Robot Programming This section details some recommended practices for safe and effective use and control of the DE2Bot At Program Start As soon as the program starts or is reset the following should be done in order 1 Immediately stop the robot by writing O to LVELCMD and RVELCMD 2 Check the battery voltage and prevent execution if it is below 13V 3 Wait for the safety switch SW17 to be toggled 4 Wait for some form of user input e g pressing a PB An example of this initialization procedure can be found in Appendix A Testing Values Two points must be kept in mind when making decisions based on values obtained from LPOS RPOS odometry sonars or any other real world measurement e Never test for exact values as there
11. iiick siscac ese vind estates vecesiesnsas vide consi lasecsnastevocavibce deveatcdevnuils Geta teGovecantaneasidetuss 11 OGOMEEIY E OE E E E E E E E E E E A E E E E 12 KUO E E E A E E A Cdaailudddneeosdede vaneudesvbadeadasicdentseecs 12 Good Practices for Robot PrograMmMing cccccssccesssecsececsnecesseesessecseneessaeeeeaaesseseeceeesseueeseaaeseeesessaeessnaeeseneeees 13 Appendix A Example starting point for ASM code cc cccccsssccssesssceceessececsesececsesaececsesaeeeceesaeeeceesuseecsesaeeeeeesaeeesesea 14 DE2Bot Hardware Overview The DE2Bot is comprised of the commercially available AmigoBot with its electronics removed and replaced with custom hardware and an Altera DE2 FPGA development board This configuration allows complete control of the robot hardware using custom digital circuits created within the FPGA Locations of important features are shown below in Figure 1 AMEER er eTo o o off g6 aaa o 0000000000000 Figure 1 Locations of important DE2Bot features Feature Descriptions Wheels and Encoders The DE2Bot has two drive wheels one on each side allowing it to use differential steering to move around smooth or dense carpeted surfaces A rear caster wheel helps to support the robot without interfering with movement The drive wheels are powered by DC motors through a reduction gearbox Each motor is equipped with a high resolution 39000 ticks per wheel revolution quadrature encoder which
12. is no guarantee that a particular value will occur Instead always test for a range o Example1 polling LPOS while the robot is moving might return OxFE at one sample and 0x100 at the next sample so testing for OxFF will never pass Testing for 20xFF would correctly trigger even if OxFF itself never occurs o Example2 many values are impossible to obtain from peripherals because of limited range or resolution For example LVEL and RVEL only have a resolution of 10 units e Be aware of edge conditions which can erroneously cause tests to pass or fail o Example 1 if the robot is facing its reset direction then ideally theta would be 0 but any small turn clockwise will change theta to 701 in which case a test for theta gt 100 intended to check if the robot has turned a certain amount will immediately pass 13 Appendix A Example starting point for ASM code SimpleRobotProgram asm Created by Kevin Johnson no copyright applied edit freely no attribution necessary This program does basic initialization of the DE2Bot and provides an xampl Section labels are for clarity only ORG amp H000 of some peripherals Begin program at x000 eKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK r Initialization CKKKKKKK a a A e A a a a r a a a a e a a A e a KKK e e KKK a a a e a a a a e E a RaT r
13. metimes it s useful to permanently to stop execution This will also catch the execution if it accidentally falls through from above LOAD OUT OUT OUT IN OUT JUMP Ze LV ro ELCMD RV SO EE SS Di ELCMD NAREN MER EG2 e 7 stop everything an indication that we are dead do this forever eKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK r Subroutines CKKKKKKK A a e A a a A e a a a e a a M A E a a A a A a e A a A E a a a a e a HK LA Subroutine to wait Waitl OUT TIMER Wloop IN TIMER OUT XLEDS ADDI 10 JNEG Wloop RETURN block for 1 second user feedback that a pause is occuring 1 second in 10Hz This subroutine will get the battery voltage and stop program execution if it is too low SetupI2C must be executed prior to this too low A D hasn t had time to initialize get original value back we want to make user realizes it BattCheck CALL GetBattLvl JZERO BattCheck SUB MinBatt JNEG DeadBatt ADD MinBatt RETURN If the battery is sure that th DeadBatt LOAD Four OUT BEEP CALL GetBattLvl OUT SSEG1 OUT SSEG2 OUT LCD LOAD Zero ADDI 1 OUT EDS OUT XLEDS CALL Waiti Load Zero OUT BEEP LOAD Zero OUT EDS OUT XLEDS CALL Waitl JUMP DeadBatt Subroutine to read th Assumes that GetBattLvl start beep
14. ng PB1 will enter the corresponding test see Table 1 below If multiple switches are up the lowest indexed test is selected While in a test pressing PB2 and PB3 together will return to the troubleshooting test selection mode Use PBO to return to the main menu TABLE 1 MANUAL TEST SELECTION po pe C SW o Switches and Pushbuttons w e a Tse is 55 Weer C Battery Test SW0 The battery voltage is continuously read and displayed on the LCD in decimal and 7 segment display in hex Speaker SW1 The robot emits a stream of beeps with 0 15s on and 0 5s off The LEDs light when the beep should be on Switches and Pushbuttons SW2 Switches 0 16 are reflected on red LEDs 0 16 The pushbuttons are reflected on the green LEDs 0 2 Sonars SW3 Switches 0 7 will individually enable sonars 0 7 The value returned by the sonar is displayed on the 7 segment display in hexadecimal If more than one sonar is enabled only the lowest indexed one s value is displayed LEDs 7 segment displays LCD SW4 All LEDs flash at 1Hz The 7 segment displays alternate between 0x1111 and OxEEEE exercising all segments The LCD alternates between blank and black Wheel Encoders SW5 SWO up down selects between the left and right wheels The selected wheel s current position value is displayed on HEX3 0 and the immediate velocity on HEX7 4 Motors SW6 Hold PB1 to power the right motor and PB2 to power the left motor Raise SWO to re
15. nly SonarO and writing 0b11111111 will enable all sonars Each enabled sonar makes its measurements available at the corresponding DIST register DISTO DIST7 This value is in mm and has a resolution of 1mm but its accuracy both linearity and offset are undefined and typically varies 5mm If no ping is returned usually because either nothing is in front of the sonar or the object is angled such that the ping bounces in another direction the value is set to the maximum positive value of Ox7FFF Sonars update in a round robin fashion at 20Hz skipping any that are not enabled If all sonars are enabled a particular measurement will update at 2 5Hz 20Hz 8 If only one sonar is enabled it will update at the full 20Hz I2C Controller and Battery Voltage The DE2Bot contains an I C bus which is currently used to communicate with the A D converter that measures the battery voltage SCOMP interfaces with the I C bus through a controller with three I O registers e 12C_CMD write only contains configuration information for the controller o bits 15 12 number of bytes to write 0 1 or 2 o bits 11 9 number of bytes to read 0 1 or 2 o bits 8 1 7 bit C address of device to communicate with excludes RnW bit obit 0 ignored the RnW bit is set on the fly according to the current operation e 12C_DATA read write data to send and data received o If transmitting or receiving one byte bits 7 0 are used o If transmitting or receiving t
16. on module enables remote communication either robot to robot or robot to PC The module is connected to the DE2 s RS 232 port and by default transparently emulates a direct connection to a central PC For the serial communication to be useful some back end software must be running on the PC which will vary from semester to semester Check with lab administrators for current functionality The UART is internally rate limited to ensure consistent results when many robots are communicating at the same time Each robot may only send six bytes at a time up to five times per second every 200ms Additionally the up to six bytes must be sent in succession within a few hundred SCOMP instructions so that they can be packaged in to a single wireless packet The communication latency from the DE2Bot to the PC and back is undefined but is typically 50 100ms Self test Operation On power up a self test program is automatically loaded from non volatile memory This program enables the user to quickly test for proper operation of the DE2Bot hardware Note the self test program uses PBO as RESET Press PBO to restart the program at any time Power up Tests As soon as the DE2Bot is turned on or when the self test is restarted with PBO e The DE2Bot beeps for 0 2s e The battery voltage is displayed in hexadecimal on the HEX5 and HEX4 seven segment displays o Voltage is in tenths of volts A7 16 7V is fully charged and 82
17. sound get the battery level display it everywhere OxFFFF all Ll EDS on 1 second stop beeping LEDs off 1 second repeat forever A D battery voltage SetupI2C has been run LOAD I2CRCmd 0x0190 write OB read 1B addr 0x90 OUT I2C_CMD 7 to I2C CMD OUT I2C_RDY start the communication CALL BlockI2C wait for it to finish IN I2C_DATA get the returned data RETURN Subroutine to configure the I2C for reading batt voltage Only needs to be done once after each reset SetupI2c CALL BlockI2C wait for idle LOAD I2CWCmd 0x1190 write 1B read 1B addr 0x90 OUT I2C_CMD 7 to T2C CMD register LOAD Zero 0x0000 A D port 0 no increment OUT I2C_DATA to I12C DATA register OUT I2C_RDY start the communication CALL BlockI2C wait for it to finish RETURN Subroutine to block until I2C device is idle BlockI2C IN I2C_RDY Read busy signal JPOS BlockI2C If not 0 try again RETURN Else return KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKKKKKKHK r Variabl es KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KK KKK KKK KKK KKK KKKKKKKKKEK f Temp DW 0 Temp is not a great name but can be useful ekxkxkxkxkxkxkxkxkxk xkxkxk xkxkxkxk xkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkxkkxxkxx k Constan though CS there is nothing stopping you
18. st fails and an error is displayed on the LCD Inform an administrator 4 Motor Test Immediately after the encoder test completes the motor test begins If the safety switch SW17 has not been toggled since reset the LCD will prompt Toggle SW17 at which point you should raise and lower SW17 Once the safety is disabled the left wheel will begin turning forwards and the LCD will display Left wheel turning 2 N 1 Y If the wheel is turning press PB1 If not press PB2 The test will then repeat with the right wheel Motor Errors If either wheel does not turn when expected If LEDG8 between HEX4 and HEX3 is flashing the battery is too low to operate the motors Turn the DE2Bot off and plug it in to a charger If LEDG8 is not flashing there is likely a problem with the motors or supporting electronics Notify an administrator Self test Finish Once the motor test is complete the LCD will display Self Test Finish PB1 Main Menu If any errors occurred during the self test a red LED will be lit as follows e LEDO 7 indicate sonar 0 7 errors e LED8 and LED9 indicate left and right encoder errors e LED9 and LED10 indicate left and right motor errors Press PB1 to return to the main menu Manual Tests From the main menu pressing PB2 will enter manual test troubleshooting mode where specific hardware can be tested more thoroughly Entering Tests Once in troubleshooting mode raising a switch and pressi
19. verse the right motor and SW1 to reverse the left motor Programming Guide At the beginning of the final project in ECE2031 students are provided with a Quartus project containing the SCOMP processor and many IO devices which interface with the DE2 and DE2Bot hardware Each of these devices is assigned an IO address in the SCOMP system as detailed in Table 2 Changes to SCOMP SCOMP and its Quartus project have been modified from lab 8 in the following ways e SCOMP clocked at 12 5MHz e All SCOMP instructions in Table 7 1 of the lab manual implemented e Subroutine stack depth increased to 6 e SHIFT instruction changed from logical to arithmetic to better support mathematical operations e Central IO_DECODER device replaces AND NAND decoders for each peripheral e O_CYCLE and IO_WRITE operation slightly modified to avoid possible contentions SCOMP Interrupt System An interrupt system is being developed for SCOMP Details will be added here when it is complete IO Device Quick Reference TABLE 2 SCOMP QUARTUS PROJECT I O DEVICE DESCRIPTIONS as _ Re PP SW AFT sano GPO oi foor Wactietcerseersemnet apes a5 Our a ae oT waetotoaesitimdetinsh a7 oT wietopeebstbGreocoaaeDRTREDRIS pon oT We t7 Tarbes wore BSO NI We oto tuneen m or or oor pa for Wiese o Tarasa so additional details in following sections 10 Detailed Description of Select Devices Wheel Position Velocity and
20. vided between all enabled sonars if only one sonar is enabled it is refreshed at 20Hz if all eight sonars are enabled the overall refresh rate is 2 5Hz 20Hz 8 Battery and Charge Port The DE2Bot contains a 5 5Ah rechargeable LiPo battery enabling several hours of idle use or approximately an hour of continuous use between charges A charge port on the side of the robot provides easy attachment of an external charger Note that when the robot s main power switch is ON the charging port is disconnected from the battery In order to charge the power switch must be in the OFF position Care should be taken to never discharge the battery below 13V Doing so will reduce the life of the battery and may cause permanent damage DE2 Development Board The Altera DE2 board provides access to a Cyclone II FPGA as well as various I O such as e 18 slide switches e four push buttons e 27 LEDs e a16x2 character LCD e eight 7 segment displays e audio in and out with ADC DAC e VGA video output e anRS 232 serial port e SD card slot The DE2 on the DE2Bot connects to the robot s internal circuitry through its GPIO ports allowing direct digital control of all robot functions Note that the DE2 s power button red button at top left of board should not be used Leave the DE2 ON and use the robot s main power switch to turn the DE2Bot on and off Wireless Serial Connection An internally mounted XBee wireless communicati
21. wo bytes bits 15 9 are the first byte then bits 7 0 e 12C_RDY read write status indicator o Writing to 12C_RDY begins an I2C transaction set up 12C_CMD and 2C_DATA first o Reading 12C_RDY will return zero if the controller is idle or non zero if a communication is in progress Do not modify 12C_CMD or I2C_DATA while 12C_RDY reads as non zero 11 Odometry The Quartus DE2Bot project contains a device that performs dead reckoning odometry continuously integrating the movement of the wheels to maintain an estimate of the robot s position and heading This estimation can be read from IO registers XPOS YPOS and THETA At power up or reset the position of the robot defaults to X Y 8 0 0 0 The coordinate system is shown in Figure 3 the reset orientation is defined as facing the positive X direction with positive Y to the left and theta following the normal right handed convention with Z upwards Writing to IO location RESETODO will reset the odometry to this position Figure 3 Coordinate system used for DE2Bot odometry The units for the X and Y positions are 1 05mm count the same as the resolution of LPOS and RPOS For theta one full rotation of the robot is divided in to 702 units a product of the robot geometry giving an approximate resolution of 0 51 count The theta value will always be 0 701 rotating counterclockwise past 701 will rollover to 0 and rotating clockwise past 0 will rollover to 701 Dead reckonin
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