Blink an LED

#define F_CPU 16000000L #include <avr/io.h> #include <util/delay.h> int main(void) { DDRB |= 0x0F; // xxxx1111 PORTB = 0x01; while (1) { _delay_ms(500); PORTB = PORTB << 1; if(PORTB == 0x10) PORTB = 0x01; } } 

#include <avr/io.h> #include <util/delay.h> #define LED_PIN PB0 DDRB |= (1 << LED_PIN); int main(void){ while (1) { PORTB |= (1 << LED_PIN); // turn the LED on _delay_ms(500); // delay for 500 milliseconds PORTB &= ~(1 << LED_PIN); // turn the LED off _delay_ms(500); // delay for 500 milliseconds } return 0; }