#define F_CPU 1000000UL
#include <avr/io.h>
#include <util/delay.h>

#define LED_PORT PORTC
#define LED PC4
#define LED_DDR DDRC
#define LED_LOW() ( LED_PORT &= (~(1 << LED)) )
#define LED_HIGH() ( LED_PORT |= (1 << LED) )
#define LED_PORT_DIR_OUT() (LED_DDR |= (1 << LED))
#define LED_PORT_DIR_IN() (LED_DDR &= (~(1 << LED)))

int main(){
  // Make PB0 an output
  LED_PORT_DIR_OUT();

  while(1){
    LED_HIGH();
    _delay_ms(10);
    LED_LOW();
    _delay_ms(900);
  }
}