// Define both left & right motors' speed & rotating direction pins
#define motorleftspeed 14
#define motorleftACW 13
#define motorleftCW 12
#define motorrightspeed 21
#define motorrightCW 22
#define motorrightACW 23

// Define push button pin for changin moving direction
#define button 4 //'0' for forward, '1' for backward

//Define potentiometer pins for speed variation control
const uint8_t slidepin1 = 35; //control left wheel speed
const uint8_t slidepin2 = 34; //control right wheel speed

// Define PWM frequency, resolution, led left & right channel
const int freq = 1000, resolution = 12, ledleft=0, ledright=1;

// Initialise the control the motor speed using PWM
int leftinput = 0, rightinput = 0, dutyCycleleft = 0, dutyCycleright = 0;

// Define boolean variable for motor direction
bool direction = true;  //true: forward, false: backward

// Interrupt Service Routine for push button to change direction
void IRAM_ATTR push_button_ISR(){
  direction = !direction;
}

void setup() {
  Serial.begin(115200);
  pinMode(slidepin1, INPUT);
  pinMode(slidepin2, INPUT);
  pinMode(motorleftCW,OUTPUT);
  pinMode(motorrightACW,OUTPUT);
  pinMode(motorleftACW,OUTPUT);
  pinMode(motorrightCW,OUTPUT);
  digitalPinToInterrupt(button);   // configure digital pin to interrupt button
  attachInterrupt(button, push_button_ISR, RISING);
  ledcSetup(ledleft, freq, resolution);    //To configure PWM signal
  ledcAttachPin(motorleftspeed, ledleft);  //Specify PWM channel 0 to motor pin D14
  ledcSetup(ledright, freq, resolution);    //To configure PWM signal
  ledcAttachPin(motorrightspeed, ledright);
}

void loop() {
  leftinput = analogRead(slidepin1);
  rightinput = analogRead(slidepin2);
  dutyCycleleft = map(leftinput,0,4095,0,1000); //Reduce range from 32bits to max 1000rpm
  dutyCycleright = map(rightinput,0,4095,0,1000);
  Serial.println("");
  Serial.print("Left wheel rotates at ");
  ledcWrite(ledleft,dutyCycleleft);
  Serial.print(dutyCycleleft);
  Serial.print(" RPM, ");
  Serial.print("Right wheel rotates at ");
  ledcWrite(ledright,dutyCycleright);
  Serial.print(dutyCycleright);
  Serial.println(" RPM");
  
  if (direction == true){
    digitalWrite(motorleftCW, HIGH);
    digitalWrite(motorrightACW, HIGH);
    digitalWrite(motorleftACW, LOW);
    digitalWrite(motorrightCW, LOW);
    if(leftinput==0 && rightinput==0){
      Serial.println("Not moving, stops");
    }else{
          Serial.println("Moving forward");
          if (leftinput>rightinput){
          Serial.println("Moving forward, turning right");
          }
          else if (leftinput<rightinput){
          Serial.println("Moving forward, turning left");
          }
      }
  }else{
    digitalWrite(motorleftCW, LOW);
    digitalWrite(motorrightACW, LOW);
    digitalWrite(motorleftACW, HIGH);
    digitalWrite(motorrightCW, HIGH);
    if(leftinput==0 && rightinput==0){
      Serial.println("Not moving, stops");
    }else{
          Serial.println("Moving backward");
          if (leftinput>rightinput){
          Serial.println("Moving backward, turning right");
          }
          else if (leftinput<rightinput){
          Serial.println("Moving backward, turning left");
          }
  }
  }
}