#define TOP_ULIMIT 4
#define TOP_LLIMIT 3
#define BTM_ULIMIT 6
#define BTM_LLIMIT 5
#define RELAY_PIN 7

// using the INPUT_PULLUP-mode inverts the ogic
// the pullup-resistor does what its name says
// pulling UP the IO-pin to HIGH
// The switch must be connected to GROUND
// closing the switch connects the IO-pin to GND = LOW

// in short opened switch: IO-pin sees HIGH
// closed switch: IO_pin sees LOW
const byte opened = HIGH;
const byte closed = LOW;

const unsigned long delayTime = 3000;

void setup() {
  Serial.begin(9600);
  digitalWrite(RELAY_PIN, LOW); // Initialize relay to off state
  pinMode(RELAY_PIN, OUTPUT);
  Serial.print("digitalRead(RELAY_PIN)=");
  Serial.println(digitalRead(RELAY_PIN) );
  pinMode(TOP_ULIMIT, INPUT_PULLUP);
  
  pinMode(TOP_LLIMIT, INPUT_PULLUP);
  pinMode(BTM_ULIMIT, INPUT_PULLUP);
  pinMode(BTM_LLIMIT, INPUT_PULLUP);
}

void loop() {
  int topULimit = digitalRead(TOP_ULIMIT);
  int topLLimit = digitalRead(TOP_LLIMIT);
  int btmULimit = digitalRead(BTM_ULIMIT);
  int btmLLimit = digitalRead(BTM_LLIMIT);
  Serial.println("reading in switches DONE");

  Serial.print("Top Upper Limit: ");
  Serial.print(topULimit);
  Serial.print(", TOP Lower Limit: ");
  Serial.print(topLLimit);
  Serial.print(", BTM Upper Limit: ");
  Serial.print(btmULimit);
  Serial.print(", BTM Lower Limit: ");
  Serial.println(btmLLimit);


  // Auto OFF Section
  if ((topULimit == closed && topLLimit == closed) || (btmULimit == opened && btmLLimit == opened)) {
    digitalWrite(RELAY_PIN, LOW);
    Serial.print("RELAY_PIN, LOW Relay OFF ");
    Serial.print("digitalRead(RELAY_PIN)=");
    Serial.println(digitalRead(RELAY_PIN) );
  }

  // Auto ON Section
  if (topULimit == opened && topLLimit == opened && ((btmULimit == closed && btmLLimit == closed) || (btmULimit == closed && btmLLimit == opened))) {
    digitalWrite(RELAY_PIN, HIGH);
    Serial.print("RELAY_PIN, HIGH Relay ON ");
    Serial.print("digitalRead(RELAY_PIN)=");
    Serial.println(digitalRead(RELAY_PIN) );

  }

  Serial.print("freeze microcontroller for ");
  Serial.print(delayTime / 1000) ;
  Serial.println(" seconds");
  Serial.println();
  delay(delayTime);
  Serial.println("reading in switch now");
}