/* main.c
 *
 * Copyright (c) 2003-2004 Susan Cotterell.
 * Permission to copy is granted provided that this header remains
 * intact. This software is provided with no warranties.
 *
 * Version : 1.0
 *
 * 8-Bit LCD Interface
 * Transmitting PIC - transmits packets to the recieving PIC
 *
 */

//--------------------------------------------------------------
// libraries
//--------------------------------------------------------------

#include    <pic.h>
#include    "sci.h"
#include    "delay.h"
#include    "../constants.h"

//--------------------------------------------------------------
// pin mapping
//--------------------------------------------------------------

#define EB_INPUT	RB0

//--------------------------------------------------------------
// global variables
//--------------------------------------------------------------

unsigned alive_tx_cnt = 0;
unsigned data_tx_cnt = 0;
bit alive_tx_flag = 0;
bit data_tx_flag = 0;

//--------------------------------------------------------------
// function declarations
//--------------------------------------------------------------

void interrupt timer_isr(void);
void eb_isr(void);
void alive_tx_isr(void);
void data_tx_isr(void);
void led_isr(void);

//--------------------------------------------------------------
// main
//--------------------------------------------------------------
main(void)
{
 	int x = 0;

  	// configure processor
	// -----------------------------------------------------------
        PORTA = 0xff;	// set output data latches to default value
	CMCON = 0x07;	// disable comparators to allow I/O
	TRISA = 0xff;	// all bits output
	TRISB = 0xff;	// all bits output, bit 1 input

	// Timer0 setup
	// -----------------------------------------------------------
	asm("CLRWDT");	// turn off watch dog timer
	OPTION = 0x47; 	// setup prescaler
	TMR0 = PRELOAD; // preload timer
	INTCON = 0xA0;	// setup interrupt control

	// -----------------------------------------------------------
	// main code
	// -----------------------------------------------------------

	


	for(;;) {

		if( data_tx_flag == 1){
			if( x % 2 ){

				// send NO Packet (000)
				// -------------------------
				RB2 = 1;
				TRISB = 0xFB;  // all inputs except RB2
				GIE = 0;

				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
								
				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
								
				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
								
				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
				RB2 = 1;
				TRISB = 0xFF;  // all inputs
				GIE = 1;

				data_tx_cnt = 0;
			}
			else{
				//send YES packet (010)
				//--------------------------
				RB2 = 1;
				GIE = 0;
				TRISB = 0xFB;  // all inputs except RB2

				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
								
				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
								
				RB2 = 1;
				DelayUs(250);
				DelayUs(55);
								
				RB2 = 0;
				DelayUs(250);
				DelayUs(55);
				RB2 = 1;
				TRISB = 0xFF;  // all inputs				
				GIE = 1;

				data_tx_cnt = 0;
			}

			x++;
			data_tx_flag = 0;
		}
		

		if( alive_tx_flag == 1){

			// send alive packet
			// ------------------------------------
			RB2 = 1;
			TRISB = 0xFB;  // all inputs except RB2
			RB2 = 0;
			DelayUs(250);
			DelayUs(55);
			TRISB = 0xFF;  // all inputs
			
			// reset alive flag
			// -------------------------------------
			alive_tx_cnt = 0;
			alive_tx_flag = 0;
		}
	}
}

//--------------------------------------------------------------
// interrupt service routine
//--------------------------------------------------------------
void interrupt timer_isr(void)
{
	T0IE = 0;	// disable timer0 interrupt
	GIE = 0;	// disables all interrupts

	alive_tx_isr();
	data_tx_isr();

	TMR0 = PRELOAD; // preload timer
	T0IF = 0;	// clear timer overflow flag
	T0IE = 1;	// enable timer0 interrupt
	GIE = 1;	// enable all interrupts
}

//--------------------------------------------------------------
// alive tx process (isr called every 10 ms)
//--------------------------------------------------------------
void alive_tx_isr(void)
{
	alive_tx_cnt++;

	if( alive_tx_cnt == 100 ) {
		alive_tx_flag = 1;
		alive_tx_cnt = 0;
	}
}

//--------------------------------------------------------------
// data tx process (isr called every 10 ms)
//--------------------------------------------------------------
void data_tx_isr(void)
{
	data_tx_cnt++;

	if( data_tx_cnt == 500 ) {
		data_tx_flag = 1;
		data_tx_cnt = 0;
	}
}