The World Leader in High Performance Signal Processing Solutions

Robotics on the Blackfin Processor

Dr. Fred MartinAssistant Professor, Computer Science

University of Massachusetts Lowell

Presentation Overview

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

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

Design Category: Robot Controllers & CPUs

CPU Power -->

Degree of Robotics Support -->

8-bit MCUOriginal HBLEGO RCXXBC/GameboyPentium 4PC/104Blackfin HB

Blackfin HB

• 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

De

gre

e o

f R

ob

oti

cs

Su

pp

ort

-->

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

The Blackfin Handy Board

Blackfin Handy Board: CPU and Memory

• 600 MHz ADI BF ’537• 64 MB SDRAM• 256 MB NAND flash• 1 MB boot flash

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

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

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

Blackfin Handy Board: PPI Camera Port

• Blackfin PPI port for CMOS cameras (e.g. Omnivision)• FPGA pass-thru (or image processing)

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

Blackfin Handy Board: Communications

Debug Agent• Built-in USB 1.1 emulator• JTAG connector for external emulator

10/100 BT Ethernet

RS232 Serial

Blackfin Handy Board: Human I/O

16x4 LCD screen

2 buttons & 4 LEDs

User knob

DAC w/amp & speaker

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

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

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

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

voidsideSensorThread_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 CodeVoid 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); }}

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