Elements of IC

IC interface instructions file types, loading, debugging

Data Objects data types, constants, variables, characters

Expressions and Operators Statements Program Flow Control Functions

main( ), library, yours LCD Printing Multi-Tasking and Processes Good Programming Practices

Good Programming Practices

Use LOTS of /* Comments */ task description is a good start no storage penalty

Use Descriptive Names constants, variables, & functions

Add more /* Comments */ Never put number constants in code /* Comments */ Really help you & the team. Use Text Formatting

indents, capitalization, etc. Debugging is easier with /* Comments */ Use Functions Extensively Did I mention use of /* Comments */ ?

/********************************************** Meaningful Encounter with a Wall Program JFY, 9/17/99;Go forward until I hit wall; stop, reverse and stop. ************************************************//* GLOBAL CONSTANTS */ int L_MOTOR = 0; /* motor port #s */ int R_MOTOR = 1; int BUMPER_SWITCH = 0; /* digital port # */ int OPEN = 0; int CLOSED = 1; float DELAY = 0.5; /* Back-up time */

void main(){ Go_Forward(); while(digital(BUMBER_SWITCH)==OPEN){;}

/* wait until I hit the wall */ alloff(); /* stop the motors */ beep(); Go_Backward(); sleep(DELAY); /* back away from wall a bit */ alloff(); printf(“I found the wall! \n”);beep(); beep(); beep();} /* END of main() */

IC Interface Program types

A-Program-File.c Find-the-Wall.lis

• persistent variables.c• constants.c• go-forward3.c• go-backward2.c• my-main.c

Location of files IC Instructions

load file.c or file.lis unload file.c [to get rid of main()] list files, list functions, list globals help quit

Line Recall & Editing , , etc.

Variables & ConstantsType must be declared at 1st Use

Data or Number Types: integer: 16 bits, ±32,767 int m=12; long: 32 bits, ±232 or 2B long k=0L; floating point, ±10±32; 7 decimal digits

• float foo = 70.;• float foo = 70.0;• float foo = 7E1;• float Zero = 0.0;

Characters, 8-bit ASCII Code• ‘x’ yields its ASCII value, 120• char string[ ] = “Hello World!”;

Arrays, a sequence of data elements int foo[6]; elements 0 to 5 int foo[ ] = {4, 0, 5, 13, 7, 127};

• foo[3] has value 13

Variables & Constants

Names case sensitive No spaces -- use under_score

Scope: Global

• declared outside a function• valid within all functions, all files.

Local: valid only within a function or {}• declared in that function, or as its argument.

Initialized when new code loaded main( ) is run hardware reset (power on, or RESET)

Persistent Global Variables Never initialized persistent int m; Place at beginning of code to preserve Use for calibration values

Operators Assignment

a = a + 2; or a += 2; Integers

Arithmetic: +, –, *, / Increment & Decrement

• b = a++; increment after assignment• b = ++a; increment before assignment

Boolean: 0 represents FALSE• OR ||, AND &&,, NOT !

Comparison• >, <, ==, >=, <=

Bitwise Logic• OR |, AND &, XOR ^, NOT ~

Long Integers: Arithmetic, but No Division Comparisons

Floating Point Arithmetic & Comparisons; math functions

Statements & Expressions Operators act upon objects of a certain type

and specify what is to be done to them. Expressions combine variables and constants

using operators to create new values. Association and precedence: ( ), [ ] Object types must match

• Changing type: (float) 3

Statements are expressions, assignments, function calls, or flow control statements which make up C programs.

Every statement ends with ;• Not required for function definition, before {

Group into meta-statement blocks with { }• Each inside statement needs a ;• No ; following the right brace • Local variables may be assigned

Functions A block of statements that performs a single,

well defined task or computation. Use of functions is critical to good programming

practice, program development & debugging. A function may return a value, & must be typed

void, int, long, float Arguments optional, but must be typed. One unique function: main( )

Only one version may be loaded Starts on reset, unless “Choose”

Example function definition:

int square(int n){ return(n*n);} /* end of square() */

Functions within functions:

float hypotenuse(int a, int b)

{

/* define local variable */

float h;

h = sqrt( (float) [square(a) +

square(b)] );

return(h);

} /* end of hypotenuse() */

sqrt() is a pre-defined library function of type float with argument type float.

Note the coercion of integer type to float h, a, & b are variables local to

hypotenuse()

Function Libraries Floating point math; RoboBoard; Yours.

Function Libraries IC\libs\robo.lis

floating point math functions Input & Output functions IR beacon functions Time and Process functions Sound functions

IC\libs\encoders.lis shaft encoder functions

Test Programs: IC\libs\ testports.lis QT.c

Your Function Definitions In IC\libs\ or IC\my-lib [specify directory] IC\libs\my-lib [specify directory]

Floating Point Functions Trigonometric, angles in radians

float sin(float angle) float cos(float angle) float tan(float angle) float atan(float tangent)

Log and Exponential float log10(float num) float exp10(float num) float log(float num) float exp(float num)

Other float sqrt(float num) (float) a ^ (float) b

• (float) 2 ^ (float) 3 returns 8

IC Library Functions

Motor Control motor(p,s); forward(p); reverse(p); off(p);

alloff(); ao(); motor_force(p); Other Outputs

led_out0(n); led_out1(n); digital_out(p,n);

External Sensor Input digital(p); 0 <= p <= 7 & 30 analog(p); 20 <= p <= 27

On-Board Conditions dip_switch(n); dip_switches(); robo_knob();

choose_button(); escape_button(); voltage();

Time reset_system_time(); seconds();

mseconds(); msleep(msec); sleep(sec);

IC Library Functions Shaft Encoding

enable_encoder(p); read_encoder(p); reset_encoder(p); disable_encoder(p);

digital ports 0, 1, 2, & 3 Sound

beep(); set_beeper_pitch(freq); beeper_on(); beeper_off(); tone(freq, sec); play(song);

IR Beacon set_ir_transmit_frequency(freq);

set_ir_receive_frequency(freq);• freq = 100 or 125

ir_transmit_on(); ir_transmit_off(); ir_receive_on(); ir_counts(p);

ir_receive_off();• digital ports 2, 3, 4, & 5

Process Functions

Program Flow Control

while ( expression )

statement if ( expression )

statement-1

else /* optional */

statement-2 for ( expr-1; expr-2; expr-3 )

statement

/* Example */int n;for (n=0; n<100; n++) printf(“&d\n”, n)

break

LCD Printing

printf( “format-string”, arg-1, arg-2, … arg-N);

Format elements: Character string: Hello World! end of line: \n Integer number in decimal: %d Integer number in hex: %x Integer number in binary: %b

• low byte only Integer (low byte) as ASCII: %c Floating point number: %f NO formatting for long type

Arguments: constants, variables, expressions. Treated as a single line even in two-line LCD;

truncated if too long.

Multiple Processes Processes can be created and destroyed

dynamically to perform particular tasks with their own local variables.

Unique process id number: pid Processes run sequentially for a given time, or

“ticks” in milliseconds default is 5 ticks

Processes can communicate through global variables

Commands int start_process(funct( ), [ticks,] [stack,]); int kill_process(pid); void defer();

/************************ Quick Test of RoboBoard, JFY 9/99; A version of "testports" that doesn't take so many button pushes. *******************/

/* Global Definitions */ float DELAY = 0.5; /* A timing delay parameter */int BEACON_PORT = 2; /* port for IR sensor test */int ON = 1;int OFF = 0;int n; /* General counter variable */

void main(){beep(); beep();printf("Quick Test:Push Choose to Start\n");clear_board();wait_for_choose();

/* Wait for Choose button to start; tests beeper, LCD, and Choose */

motor_test();LED_test();beacon_test();digital_port_test();analog_port_test();RoboKnob_test();DIPswitch_test(); printf("End: Quick Test\n");} /* End of main() */

void clear_board()/* Turn off motors, LEDs, and beacon. */

{ao();led_out0(OFF); led_out1(OFF);ir_transmit_off(); ir_receive_off();} /* end clear_board() */

void wait_for_choose() /* Debounce "choose" button */{ while(!choose_button()); while(choose_button());} /* End wait_for_choose() */

void digital_port_test()/* Read all the digital ports in sequence until

"choose" */{printf("Digital Ports Test: Choose\n");wait_for_choose();while(!choose_button()) {for(n=0;n<8;n++) {printf("Port: %d = %d\n", n, digital(n)); sleep(2.0*DELAY); if(choose_button()) break; /* don't wait whole loop */ } /* end "for" */ } /* end "while" */printf("End Digital Ports Test\n");sleep(2.0*DELAY);} /* end digital_port_test() */