/* Sensorless brushless DC (BLDC) motor control with Arduino UNO (Arduino DIY ESC).
 * This is a free software with NO WARRANTY.
 * https://simple-circuit.com/
 */

#define SPEED_UP          A0
#define SPEED_DOWN        A1
#define PWM_MAX_DUTY      255
#define PWM_MIN_DUTY      50
#define PWM_START_DUTY    100

byte bldc_step = 0, motor_speed;
unsigned int i;
void setup() {
  DDRD  |= 0x38;           // Configure pins 3, 4 and 5 as outputs
  PORTD  = 0x00;
  DDRB  |= 0x0E;           // Configure pins 9, 10 and 11 as outputs
  PORTB  = 0x31;
  // Timer1 module setting: set clock source to clkI/O / 1 (no prescaling)
  TCCR1A = 0;
  TCCR1B = 0x01;
  // Timer2 module setting: set clock source to clkI/O / 1 (no prescaling)
  TCCR2A = 0;
  TCCR2B = 0x01;
  // Analog comparator setting
  ACSR   = 0x10;           // Disable and clear (flag bit) analog comparator interrupt
  pinMode(SPEED_UP,   INPUT_PULLUP);
  pinMode(SPEED_DOWN, INPUT_PULLUP);
}
// Analog comparator ISR
ISR (ANALOG_COMP_vect) {
  // BEMF debounce
  for(i = 0; i < 10; i++) {
    if(bldc_step & 1){
      if(!(ACSR & 0x20)) i -= 1;
    }
    else {
      if((ACSR & 0x20))  i -= 1;
    }
  }
  bldc_move();
  bldc_step++;
  bldc_step %= 6;
}
void bldc_move(){        // BLDC motor commutation function
  switch(bldc_step){
    case 0:
      AH_BL();
      BEMF_C_RISING();
      break;
    case 1:
      AH_CL();
      BEMF_B_FALLING();
      break;
    case 2:
      BH_CL();
      BEMF_A_RISING();
      break;
    case 3:
      BH_AL();
      BEMF_C_FALLING();
      break;
    case 4:
      CH_AL();
      BEMF_B_RISING();
      break;
    case 5:
      CH_BL();
      BEMF_A_FALLING();
      break;
  }
}

void loop() {
  SET_PWM_DUTY(PWM_START_DUTY);    // Setup starting PWM with duty cycle = PWM_START_DUTY
  i = 5000;
  // Motor start
  while(i > 100) {
    delayMicroseconds(i);
    bldc_move();
    bldc_step++;
    bldc_step %= 6;
    i = i - 20;
  }
  motor_speed = PWM_START_DUTY;
  ACSR |= 0x08;                    // Enable analog comparator interrupt
  while(1) {
    while(!(digitalRead(SPEED_UP)) && motor_speed < PWM_MAX_DUTY){
      motor_speed++;
      SET_PWM_DUTY(motor_speed);
      delay(100);
    }
    while(!(digitalRead(SPEED_DOWN)) && motor_speed > PWM_MIN_DUTY){
      motor_speed--;
      SET_PWM_DUTY(motor_speed);
      delay(100);
    }
  }
}

void BEMF_A_RISING(){
  ADCSRB = (0 << ACME);    // Select AIN1 as comparator negative input
  ACSR |= 0x03;            // Set interrupt on rising edge
}
void BEMF_A_FALLING(){
  ADCSRB = (0 << ACME);    // Select AIN1 as comparator negative input
  ACSR &= ~0x01;           // Set interrupt on falling edge
}
void BEMF_B_RISING(){
  ADCSRA = (0 << ADEN);   // Disable the ADC module
  ADCSRB = (1 << ACME);
  ADMUX = 2;              // Select analog channel 2 as comparator negative input
  ACSR |= 0x03;
}
void BEMF_B_FALLING(){
  ADCSRA = (0 << ADEN);   // Disable the ADC module
  ADCSRB = (1 << ACME);
  ADMUX = 2;              // Select analog channel 2 as comparator negative input
  ACSR &= ~0x01;
}
void BEMF_C_RISING(){
  ADCSRA = (0 << ADEN);   // Disable the ADC module
  ADCSRB = (1 << ACME);
  ADMUX = 3;              // Select analog channel 3 as comparator negative input
  ACSR |= 0x03;
}
void BEMF_C_FALLING(){
  ADCSRA = (0 << ADEN);   // Disable the ADC module
  ADCSRB = (1 << ACME);
  ADMUX = 3;              // Select analog channel 3 as comparator negative input
  ACSR &= ~0x01;
}

void AH_BL(){
  PORTB  =  0x04;
  PORTD &= ~0x18;
  PORTD |=  0x20;
  TCCR1A =  0;            // Turn pin 11 (OC2A) PWM ON (pin 9 & pin 10 OFF)
  TCCR2A =  0x81;         //
}
void AH_CL(){
  PORTB  =  0x02;
  PORTD &= ~0x18;
  PORTD |=  0x20;
  TCCR1A =  0;            // Turn pin 11 (OC2A) PWM ON (pin 9 & pin 10 OFF)
  TCCR2A =  0x81;         //
}
void BH_CL(){
  PORTB  =  0x02;
  PORTD &= ~0x28;
  PORTD |=  0x10;
  TCCR2A =  0;            // Turn pin 10 (OC1B) PWM ON (pin 9 & pin 11 OFF)
  TCCR1A =  0x21;         //
}
void BH_AL(){
  PORTB  =  0x08;
  PORTD &= ~0x28;
  PORTD |=  0x10;
  TCCR2A =  0;            // Turn pin 10 (OC1B) PWM ON (pin 9 & pin 11 OFF)
  TCCR1A =  0x21;         //
}
void CH_AL(){
  PORTB  =  0x08;
  PORTD &= ~0x30;
  PORTD |=  0x08;
  TCCR2A =  0;            // Turn pin 9 (OC1A) PWM ON (pin 10 & pin 11 OFF)
  TCCR1A =  0x81;         //
}
void CH_BL(){
  PORTB  =  0x04;
  PORTD &= ~0x30;
  PORTD |=  0x08;
  TCCR2A =  0;            // Turn pin 9 (OC1A) PWM ON (pin 10 & pin 11 OFF)
  TCCR1A =  0x81;         //
}

void SET_PWM_DUTY(byte duty){
  if(duty < PWM_MIN_DUTY)
    duty  = PWM_MIN_DUTY;
  if(duty > PWM_MAX_DUTY)
    duty  = PWM_MAX_DUTY;
  OCR1A  = duty;                   // Set pin 9  PWM duty cycle
  OCR1B  = duty;                   // Set pin 10 PWM duty cycle
  OCR2A  = duty;                   // Set pin 11 PWM duty cycle
}