//keypad.c
//on PORTB on the NM110 LCD/LED/Keypad Board

#include <pic.h>
#include "keypad.h"

#define nop asm("nop")

char keypad(void)
{
	TRISB = 0xf0;	// upper nybble inputs lower outputs for keypad
	nop;
		
	RB0 = 0;		// 0 rotated through lower nibble
	RB1 = 1;		// upper nibble set to inputs with
	RB2 = 1;		// weak pullups - check which is lo
	RB3 = 1;
	nop;
	if(!RB4) return('0');
	if(!RB5) return('1');
	if(!RB6) return('2');
	if(!RB7) return('3');
	RB0 = 1;
	RB1 = 0;
	nop;
	if(!RB4) return('4');
	if(!RB5) return('5');
	if(!RB6) return('6');
	if(!RB7) return('7');
	RB1 = 1;
	RB2 = 0;
	nop;
	if(!RB4) return('8');	
	if(!RB5) return('9');	
	if(!RB6) return('A');
	if(!RB7) return('B');
	RB2 = 1;
	RB3 = 0;
	nop;
	if(!RB4) return('C');
	if(!RB5) return('D');
	if(!RB6) return('E');
	if(!RB7) return('F');

	return(0);		// no valid key pressed
}