// https://forum.arduino.cc/t/motor-reverse-ideas/1457053/56

const int IN1pin = 8;
const int IN2pin = 7;
const int ENApin = 9;
const int forwardSwPin = 2;
const int reverseSwPin = 3;
int PIN, PWM;              // temporary motor PWM and switch pin
bool direction, IN1, IN2;  // direction and motor states

void setup() {
  pinMode(IN1pin, OUTPUT);
  pinMode(IN2pin, OUTPUT);
  pinMode(ENApin, OUTPUT);
  pinMode(forwardSwPin, INPUT_PULLUP);
  pinMode(reverseSwPin, INPUT_PULLUP);
}

void loop() {
  if (direction == 0) {  // forward direction parameters
    IN1 = HIGH;
    IN2 = LOW;
    PWM = 255;
    PIN = forwardSwPin;
  } else {  // reverse direction parameters
    IN1 = LOW;
    IN2 = HIGH;
    PWM = 191;
    PIN = reverseSwPin;
  }

  move(IN1, IN2, PWM);     // move motor
  checklimit(PIN);         // monitor limit switch
  move(LOW, LOW, 0);       // STOP motor
  delay(3000);             // pause
  direction = !direction;  // change direction
}

void move(bool in1, bool in2, int ena) {
  digitalWrite(IN1pin, in1);
  digitalWrite(IN2pin, in2);
  analogWrite(ENApin, ena);
}

void checklimit(int pin) {
  bool pinstate = digitalRead(pin);  // read switch state
  while (pinstate == HIGH)           // while RELEASED...
    pinstate = digitalRead(pin);     // ... read switch state
}