Low Power LCD Clock - MSP430G2231

LCDClock.c

// Low-power LCD Clock
// Kenneth Finnegan, 2011
// http://kennethfinnegan.blogspot.com/


#include "msp430G2231.h"

// Pin Assignments
#define MOSI		0
#define SCK		1
#define SS		2

// Which display segment is being displayed
volatile unsigned char subsec, second, minute, hour,
						butdeb[2];

// FUNCTIONS
void shiftOut(unsigned char d);
void updateTime(void);

void main(void) {
	WDTCTL = WDTPW + WDTHOLD; // Stop Watchdog Timer

	BCSCTL2 = 0xF8; // MCLK:LFXT1CLK/8 SMCLK:LFXT1CLK
	
	butdeb[0] = butdeb[1] = 0; // Reset button debounce
	P1DIR = 0x3F; // I/O
	P1OUT = 0xFF; // All high
	P1REN = 0xC0; // Pullup on inputs
	P1IES = 0xC0; // H to L transition
	P1IFG = 0x00; // Clear noise int
	P1IE  = 0xC0; // Enable button int

	second = minute = hour = 0;
	/*shiftOut(0x80 | (minute % 10));
	shiftOut(0x40 | (minute / 10));
	shiftOut(0x20 | (hour % 10));
	shiftOut(0x10 | (hour / 10));*/
	shiftOut(0xF0); // Everything is zero

	CCTL0 = CCIE;
	CCR0 = 0;
	TACCR0 = 0x3FF; // Period of 1023 + 1 cnts, which is 32Hz
	TACTL = 0x0211; // Timer_A: SMCLK, UP MODE, TAIE


	// Sleep forever...
	_BIS_SR(LPM1_bits + GIE);
}

#pragma vector=PORT1_VECTOR
__interrupt void Port1 (void) {
	// Increment minute
	if ((P1IFG & 0x80) && !butdeb[1]) {
		butdeb[1] = 8;
		second = 0;
		minute = (minute + 1) % 60;
		shiftOut(0x80 | (minute % 10));
		shiftOut(0x40 | (minute / 10));
	}
	// Increment hour
	if ((P1IFG & 0x40) && !butdeb[0]) {
		butdeb[0] = 8;
		hour = (hour + 1) % 24;
		shiftOut(0x20 | (hour % 10));
		shiftOut(0x10 | (hour / 10));
	}
	P1IFG = 0x00;
}

// 32Hz heartbeat
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void) {
	subsec = (subsec + 1) % 32;
	if (subsec == 0) { // New second
		updateTime();
	}
	butdeb[0]?butdeb[0]--:1;
	butdeb[1]?butdeb[1]--:1;
}

void updateTime( void ) {
	second = (second + 1) % 60;
	if ( second == 0 ) { // new minute
		minute = (minute + 1) % 60;
		shiftOut(0x80 | (minute % 10));
		if ( (minute % 10) == 0) { // new 10s min
			shiftOut(0x40 | (minute / 10));
		}
		if ( minute == 0) { // new hour
			hour = (hour + 1) % 24;
			shiftOut(0x20 | (hour % 10));
			if ( (hour % 10) == 0) { // new 10s hr
				shiftOut(0x10 | (hour / 10));
			}
		}
	}
}

void shiftOut(unsigned char d) {
	int i;
	P1OUT = P1OUT & ~(1<<SS);
	for (i = 7; i>=0; i--) {
		P1OUT = (P1OUT & ~(1<<MOSI)) | (((d>>i)&1)<<MOSI);
		P1OUT = P1OUT & ~(1<<SCK);
		P1OUT = P1OUT | 1<<SCK;
	}
		
	P1OUT |= (1<<SS);
}