Robotics on the Blackfin Processor

1. Robotics on the Blackfin Processor Dr. Fred Martin Assistant Professor, Computer Science University of Massachusetts Lowell

2. Presentation Overview • History/Motivations for Educational Robot Controllers • The Blackfin Handy Board: Hardware Design • The Blackfin Handy Board: Software Environments • Classroom Support Materials • Demonstration

3. The Original Handy Board • Developed for MIT LEGO Robot Competition, starting in 1991 • Goal: Give students everything they need to start building robots • Uses 2 MHz Motorola HC11 • 32K bytes of RAM • 4 motor outputs • 7 analog, 9 digital sensor inputs • Built-in battery pack & LCD screen • “Interactive C” language • Open-source design • Over 10,000 in use Helped shape a new product category:Educational/classroom mobile robot controllers

4. Design Category: Robot Controllers & CPUs • Many options, with various levels of integration • Original Handy Board, LEGO RCX, and XBC/Gameboy provide sensor/motor I/O • Blackfin HB has powerful processor and significant robotics support integrated into one design Degree of Robotics Support -->

5. Design Goals for Blackfin Handy Board • Highlight power and capabilities of the Blackfin DSP • Vision • Advanced software development • Keep integrated, hand-held design of original HB • Support wide range of sensor/motor I/O

6. The Blackfin Handy Board

7. Blackfin Handy Board: CPU and Memory • 600 MHz ADI BF ’537 • 64 MB SDRAM • 256 MB NAND flash • 1 MB boot flash

8. Blackfin Handy Board: Robot Sub-System FPGA • Xilinx Spartan 3E series FPGA • “Board Support Package” includes • motor PWM, sensor sampling • CMOS camera PPI pass-thru • LCD driver • end-user programmable

9. Blackfin Handy Board: Motor Output • DC motor output • 4 channels bi-directional control • 1A, 12v per motor • locked antiphase & sign-magnitude PWM • back-EMF velocity sensing • motor status LEDs • Servo motor control • 8 outputs • 5A, +5v motor power supply

10. Blackfin Handy Board: Sensor Input • three ADI 12-bit A/Ds with 8-1 mux, continuously sampling at 48 kHz • 12 external analog inputs • 10 digital inputs • 8 digital outputs • two i2c connectors • integral 2-axis accelerometer

11. Blackfin Handy Board: PPI Camera Port • Blackfin PPI port for CMOS cameras (e.g. Omnivision) • FPGA pass-thru (or image processing)

12. Blackfin Handy Board: Integrated Power Sub-System • Battery/Charge • Built-in 12v (10 AA cell) 2000 mAh battery pack • Smart-charge circuit (rapid, trickle, thermal cut-off) • Charge and run simultaneously • Battery level sensor to Blackfin • Power Regulation • 5A, +5v supply for servo motors & external devices • 3.3v, 1.8v supplies for Blackfin & FPGA • high-efficient switching regulators

13. Blackfin Handy Board: Communications • Debug Agent • Built-in USB 1.1 emulator • JTAG connector for external emulator RS232 Serial 10/100 BT Ethernet

14. Blackfin Handy Board: Human I/O DAC w/amp & speaker 16x4 LCD screen User knob 2 buttons & 4 LEDs

15. Blackfin Handy Board: Software Environments • ADI Visual DSP++ • C/C++ IDDE • High-performance C compiler • VDK Kernel for threads • LWIP TCP/IP stack • gcc & uClinux • Compile standalone apps with gcc • Run uClinux kernel and compile apps that use kernel services • uBoot monitor • LabVIEW Embedded for ADI Blackfin

16. Academic Support Materials • Freely available courseware based on use of LabVIEW Embedded being developed; expected January 2007 • Robotic Explorations text (2001) will be updated based on new Blackfin Handy Board design

17. Recap: Stuff You Can Plug Directly into the Blackfin HB • Sensors: • Resistive devices (photocell, switch, thermistor) • Voltage sources (IR transistors, IR distance sensors, any 0-5v source) • Ultrasonic ranging sensors • Modulated sensors (e.g., 40 kHz IR) • i2c devices • Audio sources • Motors • 4 smallish DC motors (12v, 1A) • 8 servo motors • Big DC motors using ESCs in servo outputs (Electronic Speed Controllers) • Vision • Omnivision camera modules

18. Demonstration • Wall-following using infrared distance sensors • Multithreaded control program with separate priorities for side-mounted and front-mounted sensors • Using VDSP++ and the VDK kernel

19. void sideSensorThread_RunFunction(void **inPtr) { int side_et = 0; priority = 2; while (1) { side_et = analog(ETSIDE); // Get distance on LEFT if (side_et > 400) // Too Close to wall { clear_led(1); clear_led(2); clear_led(3); set_led(1); // Turn Away pivot_right(75, priority); } else if (side_et < 350) { clear_led(1); clear_led(2); clear_led(3); set_led(3); // Turn Toward pivot_left(75, priority); } else // On Line { clear_led(1); clear_led(2); clear_led(3); set_led(2); // Go Straight motor(2, 100, priority); motor(1, 100, priority); } } } Wall-Following Robot VDK Code Void frontSensorThread_RunFunction(void **inPtr) { int FL_et = 0; // Front Left ET int FR_et = 0; // Front Right ET unsigned int loopCount = 0; priority = 3; while (1) { FL_et = analog(ETFL); FR_et = analog(ETFR); // Detect Front Obstacle while ( (FL_et > 350) || (FR_et > 350) ) { set_led(4); // Left Obstacle if ( FL_et > FR_et + 50 ) {pivot_right(75, priority);} // Right Obstacle else if ( FR_et > FL_et + 50 ) { pivot_left(75, priority); } // Forward Obstacle else { motor(1, 0, priority); motor(2, 0, priority); } FL_et = analog(ETFL); FR_et = analog(ETFR); } clear_led(4); } }

20. More Information • Schematic design, PCB art, FPGA code, and Blackfin software libraries to be distributed with open-source license • Blackfin Handy Boards publicly available Q4 2006 • See http://www.cs.uml.edu/blackfin/ for latest and to sign up for mailing list • See LabVIEW Embedded Vision Tracking demo here in the booth