/*
=== Fast PWM on OC0A (PB0): ===
1. Set Timer0 to Fast PWM
2. Enable output on OC0A (PB0)
3. Control brightness (or motor control) with OCR0A

8000000 = F_CPU
8 = prescaler
256 = 8-bit counter
PWM freq. = 8000000 / (8 * 256) = 3906.25 Hz

=== What's Going On ===
1. Fast PWM Mode: Timer0 counts 0 → 255 repeatedly.
2. OCR0A & OCR0B:
  a. When TCNT0 == OCR0x, the corresponding pin transitions.
  b. In non-inverting mode, pin is cleared on match, set at bottom (0).
3. Duty cycle = OCR0x / 255

If OCR0A is 200:
Duty cycle = (200 / 255) x 100 = 78.43%
*/


#define F_CPU 8000000UL
#include <avr/io.h>
#include <util/delay.h>
#include <TinyDebug.h>

// Motor connected to PB1 (OC0B)

#define MOTOR_PIN PB1  // OC0B

void pwm_init(void) {
    
  DDRB |= (1 << MOTOR_PIN); // Set PB1 (OC0B) as output

  // === Timer0 Setup: Fast PWM, Non-inverting mode on OC0A ===
  // Clear OC0B on compare match, set at BOTTOM (non-inverting mode)
  TCCR0A |= (1 << COM0B1); // Non-inverting PWM on OC0B (PB1)

  // WGM01 + WGM00 = Mode 3 → Fast PWM mode  
  TCCR0A |= (1 << WGM00) | (1 << WGM01); // Fast PWM mode (Mode 3)

  // Set prescaler to clk/64 → PWM freq = 8MHz / (256 * 64) ≈ 488 Hz
  TCCR0B |= (1 << CS01) | (1 << CS00);

  // Start with motor off
  OCR0B = 0;
}

int main(void) {
  pwm_init();

  // Sweep motor speed up and down

  while (1) {
    OCR0B = 1;
    _delay_ms(1000);
    OCR0B = 254;
    _delay_ms(1000);

/*
    // Speed up
    for (uint8_t speed = 0; speed <= 255; speed++) {
      OCR0B = speed;
      _delay_ms(10);
    }

    // Slow down
    for (uint8_t speed = 255; speed > 0; speed--) {
      OCR0B = speed;
      _delay_ms(10);
    }
*/

  }
}