Arduino Nano - Motion Sensor - Relay
This tutorial instructs you how to use Arduino Nano and motion sensor to control relay. In detail:
- Arduino Nano activates the relay if motion is detected by the motion sensor
- Arduino Nano deactivates the relay if no motion is detected by the motion sensor
By connecting a relay to a light bulb, LED strip, motor, or actuator.. We can use the Arduino Nano and motion sensor to control the light bulb, LED strip, motor, or actuator...
This can be applied in an automation process that triggers actions upon detecting human presence.
Hardware Preparation
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.
Additionally, some of these links are for products from our own brand, DIYables.
Overview of Relay and Motion Sensor
If you are unfamiliar with relay and motion sensor (including pinout, functioning, programming, etc.), the following tutorials can help:
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Initial Setting
| Time Delay Adjuster | Screw it in anti-clockwise direction fully. |
| Detection Range Adjuster | Screw it in clockwise direction fully. |
| Repeat Trigger Selector | Put jumper as shown on the image. |
Arduino Nano Code
/*
* This Arduino Nano code was developed by newbiely.com
*
* This Arduino Nano code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano/arduino-nano-motion-sensor-relay
*/
#define MOTION_SENSOR_PIN 3 // The Arduino Nano pin connected to the OUTPUT pin of motion sensor
#define RELAY_PIN 2 // The Arduino Nano pin connected to the relay module
int motion_state = LOW; // current state of motion sensor's pin
int prev_motion_state = LOW; // previous state of motion sensor's pin
void setup() {
Serial.begin(9600); // Initialize the Serial to communicate with the Serial Monitor.
pinMode(MOTION_SENSOR_PIN, INPUT); // set arduino pin to input mode
pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode
}
void loop() {
prev_motion_state = motion_state; // store old state
motion_state = digitalRead(MOTION_SENSOR_PIN); // read new state
if (prev_motion_state == LOW && motion_state == HIGH) { // pin state change: LOW -> HIGH
Serial.println("Motion detected!");
digitalWrite(RELAY_PIN, HIGH); // turn on
}
else if (prev_motion_state == HIGH && motion_state == LOW) { // pin state change: HIGH -> LOW
Serial.println("Motion stopped!");
digitalWrite(RELAY_PIN, LOW); // turn off
}
}
Detailed Instructions
- Connect your Arduino Nano to your computer using a USB cable.
- Launch the Arduino IDE, select the appropriate board and port.
- Copy the code provided and open it in the Arduino IDE.
- Click the Upload button in the Arduino IDE to compile and upload the code to the Arduino Nano.
Code Explanation
Check out the line-by-line explanation contained in the comments of the source code!