// Jeffery Durand

// 
// v_03: Same POV idea, but different syntax
// 

// Button   PA3 (pin 10)
// LED      PA7 (pin 6)
// Cristal  Xtal 1 & 2 (pin 2 & 3)
#include <avr/io.h> // basic library
#include <util/delay.h> /* Functions to waste time */

// bitwise manipulations ! (though for several at a time the explicit manipulation is nice)
// WARNING: no spacing between the name and params: BIT (x) will crash
#define BIT(x) (1 << x)
#define bit_get(p,x) (p & BIT(x)) // to read: makes all zero except wanted bit x
#define bit_set(p,x) (p |= BIT(x)) // assign a 1 to wanted bit x
#define bit_clear(p,x) (p &= ~BIT(x)) // assign a 0 to wanted bit x

int main (void)
{
  /* Initialization */
  bit_set (DDRA, PA7);
  bit_set (PORTA, PA3);

  /* Event Loop */
  while (1)
  {
    /* action */
    if (bit_get(PINA, PA3) == 0) // meaning the input on PA3 is low, so ground is connected, so button is pressed
    {
      bit_set (PORTA, PA7); // turn the LED pin on
    }
    else 
    {
      bit_clear (PORTA, PA7); // turn the led pin off
      _delay_us(50);
      bit_set (PORTA, PA7); // turn the LED pin on
      _delay_us(1); // wait
    }
  }

  return (0); // never reached 
}