source: avrstuff/chiptest/main.c@ 82d2b68

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

#include <string.h>
#include <stdbool.h>

// muSerial: ATTiny2313 - LED = PD6
// K4KUSB: ATTiny2313 - LED = PB2
#define DDRLED DDRB
#define PORTLED PORTB
#define LEDBIT 1 << PB2

#define BAUD 9600 // Safe value even for low clocks. (used by setbaud.h)

int main() {
        wdt_enable(WDTO_2S);
    // configure timer 0 for a rate of FCPU/(256 * 256)
    TCCR0A = 0;          // timer 0 prescaler: 256
        TCCR0B = 4;

        //debug LED - output
        DDRLED |= 255;

        PORTLED = 0;

        // Serial baudrate - use avrlibc magic to compute the baudrate register
        // values.
        #include <util/setbaud.h>
        UBRRH = UBRRH_VALUE;
        UBRRL = UBRRL_VALUE;
        #if USE_2X
                UCSRA |= (1 << U2X);
        #else
                UCSRA &= ~(1 << U2X);
        #endif

        // Enable the serial port.
        UCSRB = (1<<RXEN) |(1<<TXEN);
        UCSRC = (1 << UCSZ1) | (1 << UCSZ0);

        // Let's rock!
        uint8_t counter = 0;
        for(;;) {
                wdt_reset();

                // Wait for timer overflow...
                if (TIFR & (1 << TOV0)) {
                        TIFR = (1 << TOV0); // reset flag
                        counter++;
                }

                if (counter == 0)
                {
                        PORTLED ^= LEDBIT; // Toggle the LED
                        UDR = 'H'; // Send a byte to the UART
                }
        }

        return 0;
}