Arduino on/off PWM

Question

When I turn on DC motor with a button I get a a fixed PWM value that goes into a loop till button state changes.

What should I change that I could change X value with potentiometer in a loop?

int X = A0;
int SW = 2;
int Xval=5;
int SWval;
int buttonNew;
int buttonOld = 1;
int buttonState= 1;
int engine = 6;
void setup() { // This executes once
  Serial.begin(9600);
  pinMode(X, INPUT);
  pinMode(SW, INPUT_PULLUP);
}
void loop() { // This loops continuously
  Xval = analogRead(X);
  buttonNew = digitalRead(SW);
if (buttonOld == 0 && buttonNew == 1) {
    if (buttonState == 0) {
      analogWrite(engine, Xval);
      buttonState = 1;
    }
    else {
      digitalWrite(engine, LOW);
      buttonState = 0;
    }
  }
buttonOld = buttonNew;
  delay(1);
  Serial.print("button");
  Serial.print(SWval);
  Serial.print("          X=");
  Serial.println(Xval);

}

Answer 1

Move the analogWrite out of the button-state-change code, and it will update the PWM continually, instead of only when the button is pressed.

See the code below.

I also change the variable name buttonState to motorState, as it indicates the state of the motor (On/Off). And I inverted it, so 1 means the motor is ON.

The other thing I did was to increase the delay to 10ms, so you don't get any issues with switch-bounce.

int X = A0;
int SW = 2;
int Xval=5;
int SWval;
int buttonNew;
int buttonOld = 1;
int motorState= 0;//indicates whether the motor is on/off
int engine = 6;
void setup() { // This executes once
  Serial.begin(9600);
  pinMode(X, INPUT);
  pinMode(SW, INPUT_PULLUP);
}
void loop() { // This loops continuously
  buttonNew = digitalRead(SW);
  if (buttonOld == 0 && buttonNew == 1) {
    if (motorState == 0) {
      motorState = 1;
    }
    else {
      motorState = 0;
    }
  }
  buttonOld = buttonNew;
if (motorState == 1) {
    Xval = analogRead(X);
    analogWrite(engine, Xval);
  }
  else {
    digitalWrite(engine, LOW);
  }
delay(10);
  Serial.print("button");
  Serial.print(SWval);
  Serial.print("          X=");
  Serial.println(Xval);

}