Robot Building Lab: Introduction Lab 1 The Handy Board and Interactive-C (IC) es/robotlab/labs/lab1.ps

Robot Building Lab: Introduction Purpose  Introduce the Handy Board micro- controller  Introduce IC programming language  Write simple control program in IC

Robot Building Lab: Introduction Handy Board  Motorola 6811 microprocessor, 2 MHz.  32K of static RAM.  ability to drive 4 DC motors.  16 x 2 character LCD screen.  2 programmable buttons, one knob, and piezo beeper.  inputs for 7 analog sensors and 9 digital sensors.  9.6v nicad battery with recharging circuit.  8-pin serial connector  Plus more … (copyright Prentice Hall 2001)

Robot Building Lab: Introduction Attaching Motors and Sensors (copyright Prentice Hall 2001)

Robot Building Lab: Introduction Connecting PC to HB

Robot Building Lab: Introduction Serial Line Circuit  HB communicates with host computer over RS-232 serial line  Serial Interface/Battery Charger board performs voltage conversion Connecting Handy Board (copyright Prentice Hall 2001)

Robot Building Lab: Introduction Interactive-C Very similar to C (subset) void main(void) { printf("Press start!\n"); start_press(); while (!stop_button()) { if (analog(0) > analog(1)) { motor(1, 0); motor(0, 50); } else { motor(0, 0); motor(1, 50); } ao(); /* end main */ } What does this program do?

Robot Building Lab: Introduction Brief Introduction to Programming in Interactive-C  Interactively –C> 1+2; –C> {start_press(); motor(0,50); stop_press(); ao();}  Downloading -write a function – “main” is the default -Download to Handy Board -Execute main() -Main() automatically executed on power up -(unless you press “start” or “stop” (re-load pcode) during power up)

Robot Building Lab: Introduction Interactive C Features  Interactive experimentation  Compiled into P-code (pseudo-code)  P-code interpreted by run-time machine language program on Handy Board  Built-in multi-tasking  Built-in libraries to access Handy Board hardware – sensor inputs, motor outputs, etc  Additional features: persistent global variables, built-in math functions, character arrays but no chars, one-dimensional arrays (multi-dimensional in some versions)

Robot Building Lab: Introduction DC Motor Output Commands  void motor(int m, int p) –Turns on the motor in port m –And runs the motor with power level p -- full forward = 100, full backward = -100 (using pulse-width modulation)  void off(int m) –Turns off motor m.  void alloff(), void ao() –Turns off all motors

Robot Building Lab: Introduction Sensor Input Commands  int digital(int p) –Returns the value of the sensor in sensor port p, as a true/false value (1 for true and 0 for false).  int analog(int p) –Returns value of sensor port numbered p. Result is integer between 0 and 255.  Ports are numbered as marked on Handy Board

Robot Building Lab: Introduction Seeking/Avoiding Light Motor(left_motor, left_light); Motor(right_motor, right_light); if (analog(left_light) <= light_thresh) motor(left, minimal_power); (From Braitenberg)

Robot Building Lab: Introduction Buttons and Knob Inputs  int stop_button() –Returns value of button labeled STOP: 1 if pressed and 0 if released.  int start_button() –Returns value of button labeled START.  int knob() –Returns the position of a knob as a value from 0 to 255.

Robot Building Lab: Introduction Example pressing buttons program void main(void) { printf("Press start!\n"); start_press(); motor(0, 50); stop_press(); ao(); /* end main */ }

Robot Building Lab: Introduction Example If-else void main(void) { printf("Press start!\n"); start_press(); if (analog(0) > analog(1)) { motor(0, 50); } else { motor(1, 50); } stop_press(); ao(); /* end main */ }

Robot Building Lab: Introduction Example While Loop void main(void) { printf("Press start!\n"); start_press(); while (!stop_button()) { motor(0,50); } ao(); /* end main */ }

Robot Building Lab: Introduction Light demo /* lightdemo.c - */ void main(void) { printf("Press start!\n"); start_press(); while (!stop_button()) { if (analog(0) > analog(1)) { motor(1, 0); motor(0, 50); } else { motor(0, 0); motor(1, 50); } ao(); /* end main */ }

Robot Building Lab: Introduction Miscellaneous Commands  void sleep(float sec) –Waits for an amount of time equal to or slightly greater than sec seconds.  void msleep(long msec) –Waits for an amount of time equal to or greater than msec milliseconds.  void beep() –Produces a tone of 500 Hertz for a period of 0.3 seconds.  Math lib: sin, cos, tan, atan, sqrt, log10, log, exp10, exp, ^  6811 machine language programs may be called

Robot Building Lab: Introduction Multi-tasking Overview  Processes can be created and destroyed dynamically during run-time.  Any C function can be spawned as a separate task.  Processes communicate through global variables.  Each time a process runs, it executes for a certain number of ticks.  All processes are kept track of in a process table; each time through the table, each process runs once (for an amount of time equal to its number of ticks).  When a process is created, it is assigned a unique process identification number or pid. This number can be used to kill a process.

Robot Building Lab: Introduction Multi-tasking Commands  int start_process( function-call( : :),[ TICK S],[ STACK- SIZ E]) –start process returns an integer, which is the process ID assigned to the new process.  int kill_process(int pid) –kill process returns a value indicating if the operation was successful.  void hog_processor() –Allocates an additional 256 milliseconds of execution to the currently running process.  void defer() –Makes a process swap out immediately after the function is called.  IC commands –Kill_all -- kills all currently running processes. –Ps -- prints out a list of the process status.

Robot Building Lab: Introduction Programming Tips  32K of RAM includes p-code interpreter and C libraries and program stack  Reduce redundant code by using functions  Comments don’t take up RAM  Write simple behaviors and then focus on how to coordinate them rather than trying to write one big encompassing behavior

Robot Building Lab: Introduction Next Week  Read on-line documents and answer questions specified at  Teams will be determined based on next week’s attendance  Lab 2: Structures and Drivetrains  Lab fee ($50) and deposit ($50) due: Bring check payable to “Drexel University” for $100. In memo field put “CS 280/680 Lab Fee/Deposit”  Sign up for class mailing list: –Send mail to from your desired –with no subject and –the body “subscribe robotlab”

Robot Building Lab: Introduction Lab 1: The Handy Board and Interactive-C (IC)  Files: – dfhttp://plan.mcs.drexel.edu/courses/robotlab/labs/lab1.p df – ard.htmlhttp://plan.mcs.drexel.edu/projects/legorobots/handybo ard.html – bmanual.pdfhttp://plan.mcs.drexel.edu/courses/robotlab/readings/h bmanual.pdf  Lab overview: –Connect HB to computer –Download IC, Start IC, experiment with command line programming –Write and download programs to HB Print to LCD screen, using buttons, knob and loops to vary output Control motor using knobs and buttons Write motor experimentation program, parameterized by port, allowing the user to run a motor at differing speeds/directions for differing durations –Test program untethered