/* 
 * 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 setupTimer() {
    // Clear the Timer/Counter Control Registers
    TCCR1A = 0;
    TCCR1B = 0;

    // Set the Waveform Generation Mode to Fast PWM, ICR1 as TOP (Mode 14)
    TCCR1A |= (1 << WGM11);    // Configure for non-inverting mode, set WGM11
    TCCR1B |= (1 << WGM12) | (1 << WGM13); // Set WGM12 and WGM13 for Fast PWM

    // Set the Compare Output Mode to non-inverting mode
    TCCR1A |= (1 << COM1A1);   // Set COM1A1 for non-inverting PWM on OC1A

    // Set the Clock Select bits to define the prescaler
    TCCR1B |= (1 << CS10); // Set CS10 for a prescaler of 1 (No prescaling)

    // Set the TOP value for 16-bit resolution
    ICR1 = 65535;  // Define the top count for maximum 16-bit resolution
}

void dutyCycle(unsigned char switch_states) {
  switch (switch_states) {
        case 0x01:
          OCR1A = 8192;
          break;
        case 0x02:
          OCR1A = 16384;
          break;
        case 0x04:
          OCR1A = 24576;
          break;
        case 0x08:
          OCR1A = 32768;
          break;
        case 0x10:
          OCR1A = 40960;
          break;
        case 0x20:
          OCR1A = 49152;
          break;
        case 0x40:
          OCR1A = 57344;
          break;
        case 0x80:
          OCR1A = 65535;
          break;
        default:
          OCR1A = 0;
          break;
      }
}

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

    cli();  
    
    DDRC = 0x00;		                 	// Port C pins configured as input
    PORTC = 0xFF;	                  	// Enabling the pull-up resistors
    DDRA = 0xFF;                      // Sets PORTA PIN7 as output

    setupTimer();

    sei();                            // Enable interupts

    while (1)
    {
      unsigned char switch_states = PINC;
      dutyCycle(switch_states);
    }
}