/*
  Title: blink_led_c.ino
  Author: Lucas Lim 
  Date Created: 19/03/2019
  Last Modified: 19/03/2019
  
  Purpose: Press the switch button to turn on LED
*/

// ----- Preamble ----- //
#include <avr/io.h>       // Defines pins, ports, etc
#include <util/delay.h>   // Functions to waste time, provide the _delay_ms() function

int main(void)

{
  // ----- Inits ----- //
   /*   
      DDRx - Data Direction Registers (port x), 
      PORTx - Port x data register
      Pinx - Port x input pins address
      Note : Simple way to rememebr PIN=Port INput, PORT= Port Outport Register Thing   
      
      Assignment operators
      To set a bit to one <name> |= (1<<PinNumber)
      To reset a bit to zero <name> &= ~(1<<PinNumber)
      To toggle a bit, <name> ^= (1<<PinNumber)
   */  
  DDRB |= (1<<PB2);         // Configure PB2 as output. 
  DDRA &= ~(1 << PA7);      // Configure PA7 as input.

  // ----- Event Loop ----- //
  while(1) // initialize infinite while loop

  {
    /*
      PORTB |= (1 << PB2);         // Turn on LED pin PB2 in PORTB
      _delay_ms(250);              // delay of 250ms
      PORTB &= ~(1 << PB2);        // Turn off LED pin PB2 in PORTB
      _delay_ms(250);              // delay of 250ms
     */
   // if (PINA & (1 << PA7)) {      // check bit 7 or "PA7" of PORTA is 0 or 1, true if 1, false if 0
   
   if (bit_is_clear(PINA, PA7)){ 
      PORTB |= (1 << PB2);          // Turn on LED pin PB2 in PORTB
   }
   else {
      PORTB &= ~(1 << PB2);         // Turn off LED pin PB2 in PORTB
   }
     
  }                                 // while loop end
}                                // main end