AVR Freaks

Wasn't that useful? Anyway, here's a couple of more examples from my t10/test directory.

Toggle a LED at 1Hz

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

int main(void)
{
    // PB2 output
    DDRB = 1<<2;

    while(1)
    {
	// Toggle PB2
	PINB = 1<<2;
	_delay_ms(500);
    }
}

Short 1Hz flash using the timer

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

int main(void)
{
    TCNT0 = 0;
    OCR0A = 0;
    // Start timer, free running with presc. 1:64
    TCCR0B = 1<<CS01 | 1<<CS00;
    
    DDRB = 1<<2;

    while(1)
    {
	// Short flash
	PORTB |= 1<<2;
	_delay_ms(1);
	PORTB &= ~(1<<2);

	// Add one second
	OCR0A += F_CPU / 64 - 1;
	// Wait for compare match
	while(!(TIFR0 & (1<<OCF0A)))
	    ;
	// Clear interrupt flag
	TIFR0 |= 1<<OCF0A;
    }
}

Short 1Hz flash using idle mode between flashes

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


EMPTY_INTERRUPT(TIM0_COMPA_vect)

int main(void)
{
    TCNT0 = 0;
    OCR0A = 0;
    // Enable compare match A interrupt
    TIMSK0 = 1<<OCIE0A;
    // Start timer, free running with presc. 1:64
    TCCR0B = 1<<CS01 | 1<<CS00;

    // PB2 output
    DDRB = 1<<2;

    set_sleep_mode(SLEEP_MODE_IDLE);

    sei();

    while(1)
    {
	// Short flash
	PORTB |= 1<<2;
	_delay_ms(1);
	PORTB &= ~(1<<2);

	// Add one second
	OCR0A += F_CPU / 64 - 1;

	// Idle mode until COMPA interrupt
	sleep_enable();
	sleep_cpu();
	sleep_disable();
    }
}

Short flash at about 1 Hz, powerdown and wakeup by watchdog interrupt.

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

// Wake up by WDT interrupt.
// Don't need to do anything here but (auto-) clearing the interrupt flag.
EMPTY_INTERRUPT(WDT_vect)


/*
  Delay in powerdown mode. Wake up by watchdog interrupt.
 */
void delay_power_down_wdt(uint8_t wdto)
{
    wdt_reset();
    wdt_enable(wdto);
    WDTCSR |= (1<<WDIE);
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    sleep_enable();
    // Make sure interrups are enabled and the I flag is restored
    NONATOMIC_BLOCK(NONATOMIC_RESTORESTATE)
    {
	sleep_cpu();
	wdt_disable();
    }
    sleep_disable();
}

int main(void)
{
    DDRB = 1<<2;

    sei();

    while(1)
    {
	// Short flash
	PORTB |= 1<<2;
	_delay_ms(1);
	PORTB &= ~(1<<2);

	delay_power_down_wdt(WDTO_1S);
    }
}

Fade PB0 and PB1 up and down using PWM

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


int main(void)
{
    int i;
    
    // PB0 and PB1 outputs
    DDRB = (1<<PB0) | (1<<PB1);
    // Timer0 in mode 14, fast PWM with ICR0 as top.
    // Enable OC0A and OC0B, lower mode bits
    TCCR0A = (1<<COM0A1) | (1<<COM0B1) | (1<<WGM01);
    // Set top to 1000
    ICR0 = 1000;
    // Start timer with prescaler 1:8 and set upper mode bits
    TCCR0B = (1<<CS01)  | (1<<WGM03) | (1<<WGM02);

    while(1)
    {
	for (i = 0; i <= 1000; i++)
	{
	    OCR0A = i;
	    OCR0B = 1000-i;
	    _delay_ms(1);
	}
	for (i = 1000; i >= 0; i--)
	{
	    OCR0A = i;
	    OCR0B = 1000-i;
	    _delay_ms(1);
	}
    }
}

Toggle a LED when a button is pressed

/*
  Button on PB2 to GND, LED on PB0.
  Toggle led when button is pressed.
  Button is debounced using timer interrupt.
 */

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

// Variable to tell main that the button is pressed (and debounced).
// Main will clear it after a detected button press.
volatile uint8_t button_down;

// Check button state on PB2 and set the button_down variable if a debounced
// button down press is detected.
// Call this function about 100 times per second.
static inline void debounce(void)
{
    // Counter for number of equal states
    static uint8_t count = 0;
    // Keeps track of current (debounced) state
    static uint8_t button_state = 0;

    // Check if button is high or low for the moment
    uint8_t current_state = (~PINB & (1<<PINB2)) != 0;
    
    if (current_state != button_state) {
        // Button is about to be pressed or released, increase counter
        count++;
        if (count >= 4) {
            // The button have not bounced for four checks, change state
            button_state = current_state;
            // If the button was pressed (not released), tell main so
            if (current_state != 0) {
		button_down = 1;
                count = 0;
            }
        }
    } else {
        // Reset counter
        count = 0;
    }
}


// Called at 100Hz
ISR(TIM0_OVF_vect)
{
    debounce();
}

int main(void)
{
    // PB0 output
    DDRB = 1<<0;
    // Enable internal pullup on PB2
    PUEB = 1<<2;

    // Timer0 in CTC mode
    TCCR0A = (1<<WGM01) | (1<<WGM00);
    // Set TOP for 100 Hz overflow rate
    OCR0A = F_CPU / 8 / 100 - 1;
    // Enable overflow interrupt
    TIMSK0 = 1<<TOIE0;
    // Start timer with presc 1:8
    TCCR0B = 1<<CS01;
    // Enable global interrupts
    sei();

    while(1)
    {
        if (button_down) {
            // Clear flag
            button_down = 0;
	    // Toggle PB0
	    PORTB ^= (1<<0);
        }
    }
}

hello and congratulations for the projects you have published, interested in trying this little cip, I tried to program it with one of your projects but I can't give me this error

Error. “Verifying Flash…Failed! address=0×0000 expected=0×0a actual=oxff

use avr studio 7 and as AVR ISP mk2 programmer