Introduction to Electrical & Computer Engineering: Robotics and IC Programming

The George Washington University Department of ECE ECE 001 - Intro: Electrical & Computer Engineering Intro to the Robotics Introducing the IC Discuss motor control using IC Hands-on programming Dr. S. Ahmadi Class 1 Slides obtained from Botball Kit Documentation

Class Outline Policy and Safety Basic IC programming Download Display Function commands Botball Part list http://www.seas.gwu.edu/~ece001/partlist.doc • Overview of Motors

How to Write a SIMPLE Interactive C (IC) Computer Program • IC is a hybrid of C designed to run on small, self-contained robot controllers void main() { } • Making decisions • If ( ) { statement } • Else( ) { statement } • Making repeated decisions • While( ) { statement }

How to Write a SIMPLE Interactive C (IC) Computer Program • IC is a hybrid of C designed to run on small, self-contained robot controllers • void main() { // This is a comment int my_variable; // “my_variable” is of type: integer my_variable = 2; // assinging a variable motor(1, my_variable); // a function call, turns on motor float my_second_variable; // “my_second_variable” is of type: float my_second_variable = 2+(3/6)^5; // mathematical expression using C my_second_variable = sqrt((a^2)+(b^2)); } • Important: All statements end with a semicolon (;). • Making decisions • If ( ) { statement } • Else( ) { statement } • Making repeated decisions • While( ) { statement }

Variable Types • What is a variable? • It holds information, for example: a number • Two types of variables we will use in ECE001 • int (16 bit integer number in IC) +/-32,767 (largest # it can hold) • float (32 bit floating point number) e.g. 3.1416

Useful Function: • Sleep(seconds); • sleep() delays the function’s execution for an amount of time equal to the number of seconds (expressed as a float) given as an argument

C Function:printf(); • Takes a quoted string and prints it out – %d is used for an integer – %f is used for a float – \n starts next character back at upper left corner (or new line on terminal) – commas separate all arguments after the quoted string • printf(“I’m printing\n”);

Handyboard Functions • start_button(); • stop_button(); • beep(); • fd(x); // makes motor “x” go forward • bk(x); // makes motor “x” go backward • ao(); // turns all motors off --- “all off”

Sample Program • When a program is run, the control moves from one statement to the next • Calculate j2 + 1 when j = 3 void main() { int r,j; /* declare r and j */ j = 3; /* assign a value to j */ r = j*j + 1; /* calculate and assign */ printf(“result is %d\n”,r); }

Making decision Using if-else condition void main() { if ( start_button()==1) { fd(1); fd(2); } else { ao(); } }

Repeating Execution: Loops • Loops are used when you want to do the same thing multiple times • E.g., beep 20 times • You could type beep(); 20 times, but there is a better way: a loop

Repetition Using while • Syntax: while (<test>) {statements} • Beep 20 times void main() { int num; /* declare counter */ num = 1; /* initialize counter */ while (num <= 20)/* loop while num is <=20*/ { beep(); /* beep once */ num = num + 1; /* add one to the counter */ } }

Get Started with IC Environment • Start the IC application • Click on the picture of the Handy Board • Click on the Connect Later button • Click on the New button (upper left corner) • Type in the program that prints out a text string • Save the file using the Save button (name it • whatever you want -- just remember where you put it).

Important Information • How to learn IC programming • http://www.kipr.org/curriculum/programming.html • Check class website for Handy board documentation • Check IC command functions • Check the handy board diagram • Return the Kit release form after you check all parts in the Kit • Homework is to be done individually

Introduction to Electrical & Computer Engineering: Robotics and IC Programming