////////////////////////////////////////////////////////////////////////////////
//
//     PIC16F877 + CMPS03 + LCD03 example
//     Written October 2005 by Gerald Coe, using HITECH PIC16 compiler
// 
//		 Displays compass bearing on the LCD03
//		 Note - assumes a 20MHz crystal
//		 
//     This code is Freeware - Use it for any purpose you like.
//
///////////////////////////////////////////////////////////////////////////////


#include <pic.h>
#include <stdio.h>
	 
__CONFIG(0x3b32);								// configuration register - see PIC data sheet for details		

#define CMPS03_ADDR	0xC0					// Factory supplied default address

void clrscn(void);							// prototypes
void cursor(char pos);
void print(char *p);
void setup(void);
unsigned int get_cmps03(void);

char s[21];										// buffer used to hold text to print

void main(void)
{
unsigned int bearing;

	setup();										// sets up the PIC16F877 I2C port
	clrscn();									// clears the LCD03 disply
	cursor(2);									// sets cursor to 1st row of LCD03
	sprintf(s,"CMPS03 Compass Test");	// text, printed into our buffer
	print(s);									// send it to the LCD03

	while(1) {									// loop forever
		bearing = get_cmps03();				// get bearing from cmps03 (round trip flight time in 1uS units)
		cursor(24);								// sets cursor to 2nd row of LCD03
		sprintf(s,"Bearing = %d.%d  ", bearing/10, bearing%10);
		print(s);								// send it to the LCD03	
		
		TMR1H = 0;								// 52mS delay - this is so that the SRF04 ranging is not too rapid
		TMR1L = 0;								// and the previous pulse has faded away before we start the next one
		T1CON = 0x31;							// 1:8 prescale and running
		TMR1IF = 0;
		while(!TMR1IF);						// wait for delay time
		TMR1ON = 0;								// stop timer	
	}
}

unsigned int get_cmps03(void)
{
unsigned int bearing;

	SEN = 1;										// send start bit
	while(SEN);									// and wait for it to clear
	ACKDT = 0;									// acknowledge bit
	SSPIF = 0;
	SSPBUF = CMPS03_ADDR;					// cmps03 I2C address
	while(!SSPIF);								// wait for interrupt
	SSPIF = 0;									// then clear it.
	SSPBUF = 2;									// address of register to read from - high byte of result 
	while(!SSPIF);								// 
	SSPIF = 0;									//
	RSEN = 1;									// send repeated start bit
	while(RSEN);								// and wait for it to clear
	SSPIF = 0;									//
	SSPBUF = CMPS03_ADDR+1;					// cmps03 I2C address - with read bit set
	while(!SSPIF);								// wait for interrupt
	SSPIF = 0;									// then clear it.
	RCEN = 1;									// start receiving
	while(!STAT_BF);							// wait for high byte of bearing
	bearing = SSPBUF<<8;						// and get it
	ACKEN = 1;									// start acknowledge sequence
	while(ACKEN);								// wait for ack. sequence to end
	RCEN = 1;									// start receiving
	while(!STAT_BF);							// wait for low byte of bearing
	bearing += SSPBUF;						// and get it
	ACKDT = 1;									// not acknowledge for last byte
	ACKEN = 1;									// start acknowledge sequence
	while(ACKEN);								// wait for ack. sequence to end
	PEN = 1;										// send stop bit
	while(PEN);									//
	return bearing;
}

void clrscn(void)
{
	SEN = 1;								// send start bit
	while(SEN);							// and wait for it to clear

	SSPIF = 0;
	SSPBUF = 0xc6;						// LCD02 I2C address
	while(!SSPIF);						// wait for interrupt
	SSPIF = 0;							// then clear it.

	SSPBUF = 0;							// address of register to write to 
	while(!SSPIF);						// 
	SSPIF = 0;							//

	SSPBUF = 12;						// clear screen 
	while(!SSPIF);						// 
	SSPIF = 0;							//

	SSPBUF = 4;							// cursor off 
	while(!SSPIF);						// 
	SSPIF = 0;							//
	 
	PEN = 1;								// send stop bit
	while(PEN);							//
}

		
void cursor(char pos)
{
	SEN = 1;								// send start bit
	while(SEN);							// and wait for it to clear

	SSPIF = 0;
	SSPBUF = 0xc6;						// LCD02 I2C address
	while(!SSPIF);						// wait for interrupt
	SSPIF = 0;							// then clear it.

	SSPBUF = 0;							// address of register to write to 
	while(!SSPIF);						// 
	SSPIF = 0;							//

	SSPBUF = 2;							// set cursor 
	while(!SSPIF);						// 
	SSPIF = 0;							//
	SSPBUF = pos;						//  
	while(!SSPIF);						// 
	SSPIF = 0;							//
	 
	PEN = 1;								// send stop bit
	while(PEN);							//
}

		
void print(char *p)
{
	SEN = 1;								// send start bit
	while(SEN);							// and wait for it to clear

	SSPIF = 0;
	SSPBUF = 0xc6;						// LCD02 I2C address
	while(!SSPIF);						// wait for interrupt
	SSPIF = 0;							// then clear it.

	SSPBUF = 0;							// address of register to write to 
	while(!SSPIF);						// 
	SSPIF = 0;							//

	while(*p) {
		SSPBUF = *p++;					// write the data 
		while(!SSPIF);					// 
		SSPIF = 0;						// 
	}

	PEN = 1;								// send stop bit
	while(PEN);							//
}


void setup(void)
{
unsigned long x;

	PORTB = 0xff;
	TRISB = 0xff;	
	TRISC = 0xff;
	PORTC = 0xff;

	SSPSTAT = 0x80;
	SSPCON = 0x38;
	SSPCON2 = 0x00;
	SSPADD = 50;						// SCL = 91khz with 20Mhz Osc

	for(x=0; x<300000L; x++);		// wait for LCD03 to initialise		
}