/* 
 * Filename: Timers_Exercise3
 * Author: George Howard
 * Date: 12/05/2024
 * Description: PURPOSE 
 */

// Task: Use the FastPWM Mode to produce a square wave with a duty cycle 
//       which is adjustable by using switches on the red shield. 
//       You can change only one switch to high and the rest to zero.
//       For each case mention the duty cycle value and your calculations.
//       Draw a timing diagram to explain how it works

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

// Workings: 

void dutyCycle() {
  switch (PORTB) {
        case 0x01:
          OCR1A = 32;
          break;
        case 0x02:
          OCR1A = 64;
          break;
        case 0x04:
          OCR1A = 96;
          break;
        case 0x08:
          OCR1A = 128;
          break;
        case 0x10:
          OCR1A = 160;
          break;
        case 0x20:
          OCR1A = 192;
          break;
        case 0x40:
          OCR1A = 224;
          break;
        case 0x80:
          OCR1A = 256;
          break;
        default:
          OCR1A = 0;
          break;
      }
}

int main(void)
{
    Serial.begin(9600);

    cli();                      // Disable interupts
    DDRA = 0x80;                // Sets PIN7 as output
    PORTA = 0x00;               // Resistors low
    DDRB = 0x00;                // All PORTB Pins to input
    PORTB = 0xFF;               // Enable Pull up resistors
 
    TCCR1A = 0x83;              
    TCCR1B = 0x04;              // Sets Mode 3 (PWM) and 256 prescaler

    OCR1A = 0;
    sei();                      // Enable interupts

    while (1)
    {
      dutyCycle();
    }
}