Arduino Nano - Motion Sensor - LED

This tutorial instructs you how to use Arduino Nano and motion sensor to control LED. In detail:

This can be applied in an automation process that triggers actions upon detecting human presence.

Hardware Preparation

1×Arduino Nano
1×USB A to Mini-B USB cable
1×HC-SR501 Motion Sensor
1×220 ohm resistor
1×Jumper Wires
1×(Optional) 9V Power Adapter for Arduino Nano
1×(Recommended) Screw Terminal Adapter for Arduino Nano

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
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Overview of LED and Motion Sensor

If you are unfamiliar with LED and motion sensor (including pinout, functionality, and programming), the following tutorials can help:

Wiring Diagram

The wiring diagram between Arduino Nano and Motion Sensor LED

This image is created using Fritzing. Click to enlarge image

Initial Setting

Time Delay AdjusterScrew it in anti-clockwise direction fully.
Detection Range AdjusterScrew it in clockwise direction fully.
Repeat Trigger SelectorPut jumper as shown on the image.
arduino motion sensor initial setting

Arduino Nano Code

/* * This Arduino Nano code was developed by * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * */ #define MOTION_SENSOR_PIN 2 // The Arduino Nano pin connected to the OUTPUT pin of motion sensor #define LED_PIN 7 // The Arduino Nano pin connected to the LED 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(LED_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(LED_PIN, HIGH); // turn on } else if (prev_motion_state == HIGH && motion_state == LOW) { // pin state change: HIGH -> LOW Serial.println("Motion stopped!"); digitalWrite(LED_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 above and open it in the Arduino IDE.
  • Click the Upload button in the Arduino IDE to upload the code to the Arduino Nano.
Arduino IDE Upload Code
  • Move your hand in front of the sensor and observe the alteration in the state of the LED.

Code Explanation

Check out the line-by-line explanation contained in the comments of the source code!

Video Tutorial