iodemo.c

Hitech microchip PIC C18 Compiler

 #include <pic18.h>
#include "iodemo.h"

void interrupt ISR(void);

void init(void);
void update_ports(void);

/* This is the test pattern array */
const unsigned char LEDDISPLAY[]={0xF8,0xF1,0xE3,0xC7,0x8F,0x1F,0x3E,0x7C,0xF8,0xF1,0xE3,0xC7,0x8F,0x1F,0x3E,0x7C};

unsigned char A;

void main(void)
{
	init();
/* After the devices are initialised, the main loop just polls timer 1. */
/* Every time timer 1 overflows, the ports will give an update to the */
/* LED panels. */
	while(1)
	{
		if(TMR1IF)
		{
			TMR1IF=0;
			TMR1H=0xF0;	/* Timer reload, adjusts the speed of LED updates */
			update_ports();	
		}
	}
}

void init(void)
{
	GIE=1; 
	IPEN=0;

	T1CON=0x81;	/* Timer 1 needs to be activated */
	TMR1IE=0;		/* No interrupts are associated with timer 1 */

	ADCON1=0x0F;	/* Set relevant port pins to digital mode, rather than analog */
	
	TRISA=0;		/* initially ports will be in output mode to display test pattern */
	TRISB=0xFF;		/* PORTB must be set as input so that the interrupts are possible */
	TRISC=0;
	TRISD=0;
	TRISE=0;
	TRISF=0;
	TRISG=0;
	TRISH=0;
	TRISJ=0;
	TRISK=0;
	RBPU=0;
	RBIE=1;		/* enable PORTB interrupts */
	RBIF=0;
}

void update_ports(void)
{
	static unsigned char index;

	index++;		/* used to adavnce the test pattern */
	index&=0x07;
	
	PORTA=LEDDISPLAY[index];	/* load test pattern to the ports */
	PORTC=LEDDISPLAY[index+1];
	PORTD=LEDDISPLAY[index+2];
	PORTE=LEDDISPLAY[index+3];
	PORTF=LEDDISPLAY[index+4];
	PORTG=LEDDISPLAY[index+5];
	PORTH=LEDDISPLAY[index+6];
	PORTJ=LEDDISPLAY[index+7];
	PORTK=LEDDISPLAY[index+3];
}

void interrupt ISR(void)
{
	unsigned char direction;

	if((RBIE)&&(RBIF))
	{
		direction=TRISC;	/* save PORTC status */

		TRISC=0xFF;	/* now make PORTC all input to read the DIP switch */
		
		switch((PORTB)&0xF0)	/* read PORTB, which port has been selected? */
		{
			case PORTASELECTED:
				TRISA=PORTC;	/* assign new direction to that port */
				break;
			case PORTCSELECTED:
				direction=PORTC;
				break;
			case PORTDSELECTED:
				TRISD=PORTC;
				break;
			case PORTESELECTED:
				TRISE=PORTC;
				break;
			case PORTFSELECTED:
				TRISF=PORTC;
				break;
			case PORTGSELECTED:
				TRISG=PORTC;
				break;
			case PORTHSELECTED:
				TRISH=PORTC;
				break;
			case PORTJKSELECTED:
				TRISJ=(PORTC&0x0F);	/* PORTJ & K share and LED panel */
				TRISK=((PORTC>>4)&0x0F);
				break;
		}
		TRISC=direction;	/* restore PORTC status */
		RBIF=0;
	}
}