/*
*****************************************************************************
*
* File Name - intrupt.c
* Function - Demonstrates a 1 mS interrupt by generating a 1Hz squarewave on
* port P0
*
* You will need:
* (1) uFlash & CCS PIC C Compiler (PCM/PCW)
*
* Instructions:
* (1) Compile & downloading to the uFlash
* (2) Observe a 1 Hz square wave on pin P0 (if you have a uS-RL4 board you
* can have a relay turning on and off with a very satisfying click!)
*
*****************************************************************************
*/
#include <uF876.h>

void init_hardware(void);		// function prototypes

/*
******************************** main ***************************************
*/

void main(void)
	{
	init_hardware();		// start up the ISR

	while(true)			// main can now implement other
		{}			// functions, the square wave
					// on P0 will continue in the
					// background without further
					// intervention.
	}

/*
************************** init_hardware ************************************
*
*	Setup the timer and enable the interrupt
*/

void init_hardware(void)
	{
	set_rtcc(0);
	setup_counters(RTCC_INTERNAL,RTCC_DIV_32);
	enable_interrupts(RTCC_ZERO);
	enable_interrupts(GLOBAL);
	}

/*
**************************** timer_isr ***************************************
*
* Once set up this function is run automatically every 1mS
* As a demonstration we will use the 1mS interrupt to generate a 1Hz
* squarewave on P0
*/
#INT_RTCC
void timer_isr()
	{
	static WORD tick_count=1000;	// a 1 mS tick counter (init to 1000)

	set_rtcc(0-156);		// timer reload value for 1ms
	
	switch(tick_count)		// depending on the tick count
		{
		case 0:				// 1mS count has reached 0 (1 second)
			tick_count=1000;	// reset the tick counter
			output_low(P0);		// set P0 low
			break;
		case 500:			// 1 mS count has reached 500 (1/2 second)
			output_high(P0);	// set P0 high
			break;
		}
	
	// do anything else you want to happen every 1 mS here

	tick_count--;				// decrement the tick count
	}