Arduino Nano ESP32 - Door Sensor
The door sensor (also known as entry sensor, contact sensor, or window sensor) is widely used in many kinds of application, especially for security. It is used to detect/monitor entrances (such as door, window ...). This tutorial provides instructions on how to use Arduino Nano ESP32 with the door sensor.
Hardware Preparation
| 1 | × | Arduino Nano ESP32 | |
| 1 | × | USB Cable Type-C | |
| 1 | × | Door Sensor | |
| 1 | × | (Optional) DC Power Jack | |
| 1 | × | Breadboard | |
| 1 | × | Jumper Wires | |
| 1 | × | (Recommended) Screw Terminal Adapter for Arduino Nano |
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Overview of Door Sensor
Door Sensor Pinout
The door sensor has two components:
- One magnet
- One reed switch, which has two wires
Just like the switch/button, we do NOT need to differentiate the two wires of the reed switch.
How Door Sensor Works
The magnet and the reed switch are installed on the door/windows as follows:
- The magnet is the movable part. It should be attached to the door/window
- The reed switch is the fixed part. It should be attached to the door frame
The two components are in contact when the door is closed.
- The reed switch circuit is closed when it is near to the magnet
- The reed switch circuit is open when it is far from the magnet
※ NOTE THAT:
Just like a button, we MUST use the pull-up or pull-down resistor on the Arduino Nano ESP32 pin, which connects to the reed switch
If we connect reed switch as follows: one wire to GND, the other to ESP32's input pin with a pull-up resistor:
- The ESP32's input pin is LOW when the magnet is near to the reed switch
- The ESP32's input pin is HIGH when the magnet is far from the reed switch
So:
- If the ESP32's input pin is LOW, the door is closed
- If the ESP32's input pin is HIGH, the door is opened
- If the ESP32's input pin changes from LOW to HIGH, the door is opening
- If the ESP32's input pin changes from HIGH to LOW, the door is closing
Wiring Diagram between Door Sensor and Arduino Nano ESP32
This image is created using Fritzing. Click to enlarge image
How To Program Door Sensor
- Initializes the Arduino Nano ESP32 pin to the digital input mode by using pinMode() function. For example, pin D2
pinMode(D2, INPUT_PULLUP);
- Reads the state of the Arduino Nano ESP32 pin by using digitalRead() function.
int door_state = digitalRead(D2);
Arduino Nano ESP32 Code - Check Door Open and Close State
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-door-sensor
*/
#define DOOR_SENSOR_PIN D2 // The Arduino Nano ESP32 pin connected to door sensor's pin
int door_state;
void setup() {
Serial.begin(9600); // Initialize the Serial to communicate with the Serial Monitor.
pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP); // set ESP32 pin to input pull-up mode
}
void loop() {
door_state = digitalRead(DOOR_SENSOR_PIN); // read state
if (door_state == HIGH) {
Serial.println("The door is open");
} else {
Serial.println("The door is closed");
}
}
Detailed Instructions
- If this is the first time you use Arduino Nano ESP32, see how to setup environment for Arduino Nano ESP32 on Arduino IDE.
- Copy the above code and paste it to Arduino IDE.
- Compile and upload code to Arduino Nano ESP32 board by clicking Upload button on Arduino IDE
- Move the magnet close to the reed switch and them move it far from the reed switch.
- Check out the result on the Serial Monitor. It looks like the below:.
COM6
The door is open
The door is open
The door is closed
The door is closed
The door is closed
The door is closed
The door is closed
The door is open
The door is open
Autoscroll
Clear output
9600 baud
Newline
Arduino Nano ESP32 Code - Detect Door-opening and Door-closing Events
/*
* This Arduino Nano ESP32 code was developed by newbiely.com
*
* This Arduino Nano ESP32 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-door-sensor
*/
#define DOOR_SENSOR_PIN D2 // The Arduino Nano ESP32 pin connected to door sensor's pin
int door_state; // current state of door sensor
int prev_door_state; // previous state of door sensor
void setup() {
Serial.begin(9600); // Initialize the Serial to communicate with the Serial Monitor.
pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP); // set ESP32 pin to input pull-up mode
door_state = digitalRead(DOOR_SENSOR_PIN); // read state
}
void loop() {
prev_door_state = door_state; // save the last state
door_state = digitalRead(DOOR_SENSOR_PIN); // read new state
if (prev_door_state == LOW && door_state == HIGH) { // state change: LOW -> HIGH
Serial.println("The door-opening event is detected");
// TODO: turn on alarm, light or send notification ...
}
else
if (prev_door_state == HIGH && door_state == LOW) { // state change: HIGH -> LOW
Serial.println("The door-closing event is detected");
// TODO: turn off alarm, light or send notification ...
}
}
- Copy the above code and paste it to Arduino IDE.
- Compile and upload code to Arduino Nano ESP32 board by clicking Upload button on Arduino IDE
- Move the magnet close to the reed switch and them move it far from the reed switch.
- Check out the result on the Serial Monitor. It looks like the below:.
COM6
The door-closing event is detected
The door-opening event is detected
Autoscroll
Clear output
9600 baud
Newline