main.c

/*
 * A4.c
 *
 * Created :  3/27/2025 5:34:04 PM
 * Author  :  Jasvin Kaur
 * V-Number:  V01041632
 
 // Assignment 4
 
 // Digital Clock Program
 // This program runs a digital clock on a 16x2 LCD using an AVR micro controller.
 // It tracks hours, minutes, seconds, and milliseconds, updating the display accordingly.
 // A timer interrupt increments time every 10ms, while button input toggles whether both lines update.
 */ 


#include "CSC230.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

// Time tracking variables
int hours = 0;
char hours_str[3]; // 2 chars + null terminator
int minutes = 0;
char minutes_str[3];
int seconds = 0;
char seconds_str[3];
int milliseconds = 0;
char milliseconds_str[4]; // 3 chars + null terminator
int disable_second_line = 0; // 0 is false.
int update_in_progress = 0;

// Synchronizes both lines of the LCD display with the current time.
void synchronize_display() {
	update_in_progress = 1; // Indicate that sync is in progress to prevent simultaneous updates.
	char time_buffer[13]; // Buffer to hold formatted time string.
	sprintf(time_buffer, "%02d:%02d:%02d:%03d", hours, minutes, seconds, milliseconds);
	lcd_xy(0,0);
	lcd_puts(time_buffer);
	lcd_xy(0,1);
	lcd_puts(time_buffer);
	update_in_progress = 0; // Sync complete.
}

// Updates the LCD display at a specific column with a given value.
void modify_display(int column, char value[]) {
	if (!update_in_progress) {
		lcd_xy(column, 0);
		lcd_puts(value);
		if (!disable_second_line) {
			lcd_xy(column, 1);
			lcd_puts(value);
		}
	}
}

// Initializes ADC for button input.
void initialize_lcd_buttons() {
	ADCSRA = 0x87;
	ADMUX = 0x40;
}

// Configures Timer1 to generate interrupts every 10ms.
void configure_timer1() {
	TCCR1B |= (1 << WGM12); // Set to CTC (Clear Timer on Compare) mode.
	TCCR1B |= (1 << CS11) | (1 << CS10); // Set prescaler to 64.
	OCR1A = 2499; // Compare match after 10ms at 16MHz clock.
	TIMSK1 |= (1 << OCIE1A); // Enable compare match interrupt.
	sei(); // Enable global interrupts.
}

// Initializes all system components.
void system_initialize() {
	lcd_init();
	synchronize_display();
	initialize_lcd_buttons();
	configure_timer1();
}

// Checks button input and toggles second line display when 'SELECT' is pressed.
void monitor_buttons() {
	ADCSRA |= 0x40; // Start ADC conversion.
	while (ADCSRA & 0x40); // Wait for conversion.
	unsigned int adc_value = ADCL;
	unsigned int adc_value_high = ADCH;
	adc_value += (adc_value_high << 8);
	if (adc_value > 545 && adc_value < 800) {
		disable_second_line = !disable_second_line;
		synchronize_display();
	}
}

// Increments hours and updates display.
void increment_hours() {
	hours = (hours < 99) ? hours + 1 : 0;
	if (hours == 0) {
		synchronize_display();
		} else {
		sprintf(hours_str, "%02d", hours);
		modify_display(0, hours_str);
	}
}

// Increments minutes and updates display.
void increment_minutes() {
	minutes = (minutes < 59) ? minutes + 1 : 0;
	sprintf(minutes_str, "%02d", minutes);
	modify_display(3, minutes_str);
	if (minutes == 0) {
		increment_hours();
	}
}

// Increments seconds and updates display.
void increment_seconds() {
	seconds = (seconds < 59) ? seconds + 1 : 0;
	sprintf(seconds_str, "%02d", seconds);
	modify_display(6, seconds_str);
	if (seconds == 0) {
		increment_minutes();
	}
}

// Increments milliseconds by 10ms and updates display.
void increment_milliseconds() {
	milliseconds = (milliseconds < 990) ? milliseconds + 10 : 0;
	sprintf(milliseconds_str, "%03d", milliseconds);
	modify_display(9, milliseconds_str);
	if (milliseconds == 0) {
		increment_seconds();
	}
}

// Timer1 Interrupt Service Routine (ISR), triggered every 10ms.
ISR(TIMER1_COMPA_vect) {
	increment_milliseconds();
}

// Main function - initializes system and enters infinite loop.
int main(void) {
	system_initialize();
	while(1) {
		monitor_buttons();
		_delay_ms(250); // delay to prevent multiple rapid button presses.
	}
}