Hen door with Arduino

2019-05-20 - Authored by: daedemon

Automatic Hen Door

I have hens. They have to be let out at about 11 am and shut in about an hour after dark every day. This is rather problematic as I am in school at 11 am most days. This means I can only let out the hens once I come home from school. Hardly a satisfactory arrangement as it means the hens are only out for about 2 hours in winter.

Enter Arduino

The only logical way to solve this issue is to remove the root of the problem - school. When I was told “No, you can’t leave school”, I had to find another way. I decided to use an arduino to open the hen door at 11 am ish and close the door shortly after dark.


My first design inherently flawed the arduino was not able to deliver the power necessary to move the hen door.

As you can see the power for the motor comes from arduino itself. This was not sufficient for the motor necessary to move the hen door.


As the arduino would fry if I tried to use it to handle mains power for the motor directly I needed to use relays. These allowed me to use full mains power to drive my motor without frying the arduino.


int sensorPin = A0; // select the input pin for LDR
int sensorValue = 0; // variable to store the value coming from the sensor
int doorShut=0;

void setup()
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);

void loop()
  sensorValue = analogRead(sensorPin); // read the value from the sensor
  Serial.println(sensorValue); //prints the values coming from the sensor on the screen

// change 100 to the read value of the ldr in the late evening when it is mostly dark
if (100 > sensorValue & doorShut == 0)
    delay (1000);		// change to 2 hours for actual circuit
    digitalWrite (10, HIGH);
    delay (1000);		// length of time for motor to spin
    digitalWrite (10, LOW);
    doorShut = 1;
// change 700 to the read value of the ldr in the early morning
else if (800 < sensorValue & doorShut == 1)
    delay (1000);		// change to 5 hours for actual circuit 
    digitalWrite (11, HIGH);
    delay (1000);		// motor spin time
    digitalWrite (11, LOW);
    doorShut = 0;

MK1 can be found here and MK2 can be found here