/*
*****************************************************************

  timer0.c - timer demo modified to polls switch on RA3
  
  modified by Doug Rice, 28/11/2009
  
  
*****************************************************************
*/
#include	<htc.h>

#define dev16F886 1
//#define dev16F690 1

#ifdef dev16F886

/* config for 16F886 */
//__CONFIG(WDTDIS & INTCLK & UNPROTECT & MCLREN & BORDIS & LVPDIS & IESODIS & FCMDIS ); // Program config. word 1
__CONFIG(WDTDIS & INTCLK & UNPROTECT & MCLRDIS & BORDIS & LVPDIS & IESODIS & FCMDIS ); // Program config. word 1
__CONFIG(FCMEN); // Program config. word 2

#endif

#ifdef dev16F690
/* config for 16F690 */
//__CONFIG(WDTDIS & INTCLK & UNPROTECT & MCLREN & BORDIS &  IESODIS & FCMDIS ); // Program config. word 1
__CONFIG(WDTDIS & INTCLK & UNPROTECT & MCLRDIS & BORDIS &  IESODIS & FCMDIS ); // Program config. word 1
#endif

/*
 *	Example code for using timer0 on a 16F690
 *	sets up tmr0. When it matures poll the switches and increments a variable
 */

/*
 *	Calculate preload value for one second timer
 */

#define	PERIOD	1000000		// period in uS - one second here
#define	XTAL	4000000		// crystal frequency - 4MHz

#define IPERIOD	(4 * 1000000 / XTAL)	// Period of instruction clock in uSeconds

//#define	SCALE	256		// Timer 0 prescaler
//#define T0_TICKS 256	// Number of counts for interrupt

#define	SCALE	16		// Timer 0 prescaler
#define T0_TICKS 16	// Number of counts for interrupt


#define TICK_PERIOD (SCALE * IPERIOD)	// Period (uSec) of one increment of timer 0

// #define	RELOADS	((PERIOD/T0_TICKS)/TICK_PERIOD)
#define	RELOADS	1


#ifdef dev16F886
#define PORT_BUTTONS	PORTE
#define PORT_BUTTON		3

#endif

#ifdef dev16F690
#define PORT_BUTTONS	PORTA
#define PORT_BUTTON		3

#endif



void incLed();
void setLed();

// unsigned long	seconds;	// second count
near char reload = 0;
near char count  = 0;
near char divide = 0;
near char holdoff = 0;
// unsigned long shiftReg = 0;
near unsigned char shiftReg = 0;

near char lastPortButton =0xff;
near char newPortButton =0xff;
near char pressedPortButton = 0;
near char releasedPortButton = 0;

/* service routine for timer 0 interrupt */
void interrupt
timer0_isr(void)
{
	if(reload == 0){
		// effect a change on PORTB whenever our desired period is reached.
		// Note this timing will contain a margin of error.
		reload = RELOADS + 1;
		// seconds++;
		// PORTB++;	// effect a change on PORTB  - debugger interferes with this so shadow
      setLed();
	}
	reload--;
	T0IF = 0;
}

void setLed(){
	// effect a change on PORTB whenever our desired period is reached.
	// Note this timing will contain a margin of error.
	//reload = RELOADS + 1;
	//seconds++;
	// PORTB++;	// effect a change on PORTB  - debugger interferes with this so shadow
	//count++;		
	#ifdef dev16F886
		//PORTB=count;
		PORTB= ( shiftReg & 0x0f );
	#endif

	#ifdef dev16F690
		//PORTC=count;
		PORTC= ( shiftReg & 0x0f );
	#endif
}

void IPpollSwitches(){
	// Poll buttons 
	lastPortButton = newPortButton;
	newPortButton  = PORT_BUTTONS;

	//  lastPortButton ----_____
	//  newPortButton  -----____
    
	pressedPortButton = pressedPortButton | ( lastPortButton & ~newPortButton );         

	//  lastPortButton ___----
	//  newPortButton  __-----

	releasedPortButton = releasedPortButton | ( ~lastPortButton & newPortButton );         


}

main()
{
	// initialize timer 0; 
	
	OPTION = 0b011;		// prescale by 256
	T0CS = 0;			// select internal clock
	T0IE = 1;			// enable timer interrupt
	GIE = 0;			// enable global interrupts

	#ifdef dev16F886
	TRISB = 0;			// output changes on LED
	#endif
	
	#ifdef dev16F690
	TRISC = 0;			// output changes on LED
	#endif
	
//	for(;;)
//		continue;		// let interrupt do its job

	IPpollSwitches()	;
	pressedPortButton = 0 	;
	

    while( 1 ){
	    
	    
	  // test if button has just been pressed			
	  if ( pressedPortButton & 1 << PORT_BUTTON ) {
 	    // clear the event
		pressedPortButton = pressedPortButton & ~(1 << PORT_BUTTON ) ;
		    
		// do something
		//count++;
		holdoff = 2;
		shiftReg = shiftReg+shiftReg+1;
		setLed();	    	    
	  }

	  if ( releasedPortButton & 1 << PORT_BUTTON ) {
		// clear the event
		releasedPortButton = releasedPortButton & ~(1 << PORT_BUTTON ) ;
		    
		// do something
		//count++;
		holdoff = 2;
		shiftReg = shiftReg+shiftReg+1;
		setLed();	    	    
	  }
  
	  if ( T0IF ) {		
	    // poll switches eevry time that TMR0 matures.
		IPpollSwitches();
		
	
  		divide ++;
		if( divide == 244 ) {
		  divide = 0;
	#ifdef dev16F886
		  if ( ( holdoff == 0 ) && ( PORTB=shiftReg != 0 ) ) {
	#endif
	#ifdef dev16F690
		  if ( ( holdoff == 0 ) && ( PORTC=shiftReg != 0 ) ) {
	#endif
		    shiftReg = shiftReg >> 1;
		    setLed();
		  } else { 	  
		    holdoff--;
		  }  
		}
		// clear TMR0 event
		T0IF = 0;
	  }	
	}
}