/*
  Forum: https://forum.arduino.cc/t/two-limit-switches-and-a-gear-motor/1159503/21
  Wokwi: https://wokwi.com/projects/373403879525605377

*/

enum barrierStates {
  UNKNOWN,
  DOWN,
  GOING_UP,
  UP,
  GOING_DOWN
};

enum barrierStates barrierState;

const uint8_t upLimitSwitchPin = 5;    // UNO pin 4
const uint8_t downLimitSwitchPin = 6;  // UNO pin 5
const uint8_t touchSwitchPin = 2;      // UNO Pin 6

uint8_t upLimitSwitch;
uint8_t downLimitSwitch;
uint8_t touchSwitch;
uint8_t prevTouchSwitch;

#define AIN1 3
#define AIN2 4

void setup() {
  Serial.begin(9600);
  pinMode( upLimitSwitchPin, INPUT_PULLUP );
  pinMode( downLimitSwitchPin, INPUT_PULLUP );
  pinMode( touchSwitchPin, INPUT_PULLUP );

  pinMode(AIN1, OUTPUT);
  pinMode(AIN2, OUTPUT);

  delay(100);
  touchSwitch = digitalRead( touchSwitchPin );
  prevTouchSwitch = touchSwitch;

  // a HIGH here means the limit switch is open
  upLimitSwitch = digitalRead( upLimitSwitchPin );
  downLimitSwitch = digitalRead( downLimitSwitchPin );

  // determine the initial barrier position
  if ( upLimitSwitch == LOW && downLimitSwitch == LOW ) {
    Serial.println(F("ERROR - both limit switches activated"));
    while (1);
  }
  else if ( upLimitSwitch == HIGH && downLimitSwitch == HIGH ) {
    barrierState = UNKNOWN;
    Serial.println(F("BARRIER POSITION UNKNOWN"));
  }
  else if ( upLimitSwitch == LOW ) {
    Serial.println(F("BARRIER UP"));
    barrierState = UP;
  }
  else {
    Serial.println(F("BARRIER DOWN"));
    barrierState = DOWN;
  }
}

void loop() {
  // assume HIGH = switch touched
  touchSwitch = digitalRead( touchSwitchPin );

  switch ( barrierState ) {
    case UNKNOWN:
      digitalWrite(AIN2,HIGH);
      upLimitSwitch = digitalRead( upLimitSwitchPin );
      if ( upLimitSwitch == LOW ) {
        digitalWrite(AIN2,LOW);
        Serial.println(F("BARRIER UP"));
        barrierState = UP;
      }
      break;

    case DOWN:
      if (( touchSwitch != prevTouchSwitch ) && ( touchSwitch == HIGH ) ) {
        digitalWrite(AIN2,HIGH);
        Serial.println(F("BARRIER GOING UP"));
        barrierState = GOING_UP;
      }
      break;

    case GOING_UP:
      upLimitSwitch = digitalRead( upLimitSwitchPin );
      if ( upLimitSwitch == LOW ) {
        digitalWrite(AIN2,LOW);
        Serial.println(F("BARRIER UP"));
        barrierState = UP;
      }
      break;

    case UP:
      if (( touchSwitch != prevTouchSwitch ) && ( touchSwitch == HIGH ) ) {
        digitalWrite(AIN1,HIGH);
        Serial.println(F("BARRIER GOING DOWN"));
        barrierState = GOING_DOWN;
      }
      break;

    case GOING_DOWN:
      downLimitSwitch = digitalRead( downLimitSwitchPin );
      if ( downLimitSwitch == LOW ) {
        digitalWrite(AIN1,LOW);
        Serial.println(F("BARRIER DOWN"));
        barrierState = DOWN;
      }
      break;
  }
  prevTouchSwitch = touchSwitch;
}