timer.c

#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdio.h>
#include <stdlib.h>

#define C2

#define DDR_SPI DDRB
#define PORT_SPI PORTB
#define DD_MOSI DDB2
#define DD_SCK DDB1
#define DD_SS DDB0

void SPI_MasterInit()
{
	DDR_SPI = (1 << DD_MOSI) | (1 << DD_SCK) | (1 << DD_SS);
	PORT_SPI = 0b1;
	
	SPCR = (1 << SPE) | (1 << MSTR) | (1<<SPR0);
}

void SPI_MasterTransmit(char ch)
{
	PORT_SPI = 0b0;
	SPDR = ch;
	while(!(SPSR & (1<<SPIF)));
	PORT_SPI = 0b1;
}

void SPI_MasterTransmitString(char *str)
{
	while (*str) {
		SPI_MasterTransmit(*str);
		str++;
	}
}

void sleep(const int milliseconds) {
	for (int j = 0; j < milliseconds; j++) {
	     for (int i = 0; i < (8000 / 18 - 28); i++);
	}
}

void sleep_using_timer(const int milliseconds) {
	TCCR1B |= (1 << CS10);
	
	for (int c = 0; c < milliseconds * 0.160; c++) {
		TCNT1 = 0;
		while (TCNT1 < 50000);
	}
}

volatile int millis = 0;
volatile int seconds = 0;
volatile int minutes = 0;

int main()
{
	DDRA = 0xFF;
	PORTA = 0x00;

#ifdef A1	
	while (1) {
		sleep(10000);
		PORTA = ~PORTA;
	}
#endif

#ifdef B1
    while (1) {
		sleep_using_timer(10000);
		PORTA = ~PORTA;
	}
#endif

#ifdef C1
	while (1) {
		sleep_using_timer(500);
		PORTA = ~PORTA;
	}
#endif

#ifdef A2
	TCCR0B |= (1 << CS01);
	TIMSK0 |= (1 << TOIE0);
	sei();
	while (1);
#endif

#ifdef B2
	SPI_MasterInit();
	
	TCCR0B |= (1 << CS01);
	TIMSK0 |= (1 << TOIE0);
	sei();
	while (1);
#endif

#ifdef C2
	DDRC = 0x00;
	
	SPI_MasterInit();
	SPI_MasterTransmitString("\e[j 0: 0:  0");
	
	TCCR0B |= (1 << CS01);
	TIMSK0 |= (1 << TOIE0);
	
	uint8_t previous_keys = 0;
	
	while (1) {
		uint8_t keys = PINC;
		uint8_t changed_and_pressed = keys & ~previous_keys;
		
		if (changed_and_pressed & 0b0001) {
			sei();
		}
		
		if (changed_and_pressed & 0b0010) {
			cli();
			char buffer[20];
			sprintf(buffer, "\e[j%2d:%2d:%3d (s)", minutes, seconds, millis);
			SPI_MasterTransmitString(buffer);
		}
		
		if (changed_and_pressed & 0b0100) {
			cli();
			millis = seconds = minutes = 0;
			SPI_MasterTransmitString("\e[j 0: 0:  0");
		}
		
		previous_keys = keys;
	}
#endif
}

ISR (TIMER0_OVF_vect)
{
	static int c = 0;
	
	c++;

#ifdef A2	
	if (c == 4000) {
		PORTA++;
		c = 0;
	}
#endif

#ifdef B2
	if (c == 4) {
		millis++;
		
		if (millis >= 1000) {
			seconds++;
			millis = millis % 1000;
		}
		
		if (millis % 13 == 0) {
			char buffer[20];
			sprintf(buffer, "\e[j%2d:%2d:%3d", minutes, seconds, millis);
			SPI_MasterTransmitString(buffer);
		}
		
		if (seconds >= 60) {
			minutes++;
			seconds = seconds % 60;
		}
		
		c = 0;
	}
#endif

#ifdef C2
	if (c == 4) {
		millis++;
		
		if (millis >= 1000) {
			seconds++;
			millis = millis % 1000;
		}
		
		if (millis % 13 == 0) {
			char buffer[20];
			sprintf(buffer, "\e[j%2d:%2d:%3d", minutes, seconds, millis);
			SPI_MasterTransmitString(buffer);
		}
		
		if (seconds >= 60) {
			minutes++;
			seconds = seconds % 60;
		}
		
		c = 0;
	}
#endif
}