/*
** Program COMPASS1.C
**
** This program interfaces the serial port with the V2X Compass Module.
** Compass bearings are continually taken and sent to RF
*/

#include <16F876.H>

#fuses   HS,NOPROTECT,NOWDT
#use delay (clock = 20000000) 

 
#define COMPASS_SDO    		PIN_C4
#define COMPASS_RESET 		PIN_B1
#define COMPASS_PC		PIN_B2
#define COMPASS_EOC		PIN_B0
#define COMPASS_SCLK   		PIN_B4

long data = 0;
int read_done = 0;

/* works properly*/
void reset_compass(){

	//set the signal lines
	output_high(COMPASS_RESET);	
	output_high(COMPASS_PC);
	output_high(COMPASS_SCLK);
	
	//reset the compass
	output_low(COMPASS_RESET);
	delay_ms(15);
	output_high(COMPASS_RESET);

	//delay before the first read
	delay_ms(550);

}


void init_read_compass(){

	//output_high(COMPASS_RESET);
	
	//give a pulse to compass
	output_low(COMPASS_PC);
	delay_ms(15);
	output_high(COMPASS_PC);

}


#int_ext
void read_compass() {
   	short int j;
	int i;

	//output_high(COMPASS_RESET);

	//delay at least 10 msec before reading
	delay_ms(10);
	
	//PC and SS are connected together!
	output_low(COMPASS_PC); 		

	//create the first 8 cycles
	for ( i = 0; i < 8; i++) {
		output_low (COMPASS_SCLK);
		delay_us(15);
		output_high (COMPASS_SCLK);
		delay_us(15);
		j = input(COMPASS_SDO);
		data = (data<<1) | j; 
		
	}

	//this delay is application dependent
	delay_ms(5);

	//create the second 8 cycles
	for ( i = 0; i < 8; i++) {
		output_low (COMPASS_SCLK);
		delay_us(15);
		output_high (COMPASS_SCLK);
		delay_us(15);

		j = input(COMPASS_SDO);
		data = (data<<1) | j; 
	}
 
	//set SS high again (SS and PC are connected)
	output_high(COMPASS_PC);
	read_done = 1;

}



#use rs232(baud=19200, xmit=PIN_C6, rcv=PIN_C7)
void main(){
	
	byte messageByte [7];
	int i;

	messageByte[0] = 50;   	//To/From
	messageByte[1] = 1;	//packet ID
	messageByte[2] = 4;	//message length
	messageByte[3] = 2;	//start of message indicator
	messageByte[6] = 3;	//end of message indicator

	ext_int_edge( l_to_h );
	enable_interrupts(global);
	enable_interrupts(ext_int);
	
	//printf("\r\nStarted!\n\r");
	
	reset_compass();
	//printf("Compass resetted!\n\r");

	delay_ms(2000);

	while(TRUE){

		init_read_compass();

		//printf("read_done: %U\n\r", read_done);
		
		delay_ms(150);
		
		if (read_done){

			//printf("Data: %lu\n\r", data);

			messageByte[4] = data >> 8;
			messageByte[5] = data;

			for (i = 0; i < 7; ++i){
				putchar(messageByte[i]);
			}

			if (messageByte[1] < 7)
				++messageByte[1] ;

			else 
				messageByte[1] = 1;

			read_done = 0;
		}

		delay_ms(3000);
	}

}