Led + Button + Timer + UART

Материал из Automata.

#include <stdint.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

#define BUT_PIN 0x10
#define LED_PIN 0x01
#define TST_MES 0xA5
#define ONE_SEC 31250
#define MSG_LEN 12

const char msg[] = "set Hz freq";

char led_stat;
char led_freq;

void snd_byte (uint8_t byte)
{
	UDR = byte;
	while (!(UCSRA & _BV(TXC)));
	UCSRA |= _BV(TXC);
}

void but_test (void)
{ 
    if (!(PINB & BUT_PIN)) { 
        _delay_ms(5); 
        led_stat ^= 1; 
        while (!(PINB & BUT_PIN)); 
        _delay_ms(5); 
   } 
} 

inline void led_trig (void)
{ 
	PORTB ^= LED_PIN;
}

ISR (TIMER1_COMPA_vect)
{
    led_trig();
}

ISR (USART_RX_vect)
{
	OCR1A = ONE_SEC/UDR; 
	snd_byte('O');
	snd_byte('K');
}

int main ()
{
       //pin 0 - led act GND, pin 4 - button act GND
	DDRB = 0x01;
	PORTB = 0x10;
	
       //CTC, presc 256
	TCCR1B = _BV(WGM12) | _BV(CS12);
	TIMSK  = _BV(OCIE1A);
	OCR1A  = ONE_SEC;

       //19.2k , 8 db, 1sb, no parity
	UBRRH = 0;
	UBRRL = 25;	
	UCSRB = _BV(RXCIE) | _BV(RXEN) | _BV(TXEN);
	UCSRC = _BV(URSEL) | _BV(USBS) | _BV(UCSZ0) | _BV(UCSZ1);	

	for (int i = 0; i < MSG_LEN; ++i)
		snd_byte(msg[i]);
	
	led_freq = 100;
	
	sei();
	
	while (1) {
		but_test();
		if (led_stat)
			TIMSK  |= _BV(OCIE1A);
		else 
			TIMSK  &= ~_BV(OCIE1A);
	}
	
	return 0;
}