Hardware Hacking Projects for Geeks

261

Chapter 13, How to Make RC Cars Play Laser Tag

Exhibit B: RC Car Hack Software Code

// radio control car hack

// (4/26/03 Scott Fullam

// feel free to modify this code

#include <P16F876A.h>

#define var_res_clk 0x01

void gen_2khz(int cycles);

void init_code();

void check_hit();

void check_fire();

char hit_count;

char shot_count;

void update_score(char num);

#pragma CLOCK_FREQ 1600000

// #pragma RESERVE_ADDR_0 // add this line back in if you are using the ICD2 and debugging code

void main()

{

init_code();

while(1)

{

check_fire();

check_hit();

}

}

void init_code()

{

// set pr2 divider to 25. this plus the prescaler value of 4 will generate

// a 38461 kHz out from CPP1 using a system crystal of 16 MHz

pr2 = 25;

ccpr1l = 0x0D;

// set the diver bits but do not set PWM mode yet

ccp1con = 0x00;

// set up portc 2 as an output, 0,1 as inputs

trisc = 0x03;

// set prescaler to 4 and switch timer 2 on

t2con = 0x05;

// porta 2-5 as outputs. the others as inputs

// set adcon1 so that all pins are digital I/O

adcon1 = 0x07;

trisa = 0x00;

// set up timer1 for 2 kHz (or 3 kHz) modulation generation

t1con = 0x20;

hit_count = 0;

Exhibit B

ch13_rc.indd 261

1/22/2002 4:44:43 PM

262

Part II: Advanced Hacks, Tools, and Techniques

shot_count = 15;

porta = 0x00;

}

void gen_2khz(int cycles)

{

int i;

char temp1;

for (i = 0; i < cycles; ...