Arduino - Motion Sensor - LED

We are going to learn how to:

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×HC-SR501 Motion Sensor
1×LED
1×220 ohm resistor
1×Breadboard
4×Jumper Wires
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About LED and Motion Sensor

If you do not know about led and motion sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino Motion Sensor LED Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Arduino Code

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-motion-sensor-led */ const int MOTION_SENSOR_PIN = 7; // Arduino pin connected to the OUTPUT pin of motion sensor const int LED_PIN = 3; // Arduino pin connected to LED's pin int motionStateCurrent = LOW; // current state of motion sensor's pin int motionStatePrevious = LOW; // previous state of motion sensor's pin void setup() { Serial.begin(9600); // initialize serial pinMode(MOTION_SENSOR_PIN, INPUT); // set arduino pin to input mode pinMode(LED_PIN, OUTPUT); // set arduino pin to output mode } void loop() { motionStatePrevious = motionStateCurrent; // store old state motionStateCurrent = digitalRead(MOTION_SENSOR_PIN); // read new state if (motionStatePrevious == LOW && motionStateCurrent == HIGH) { // pin state change: LOW -> HIGH Serial.println("Motion detected!"); digitalWrite(LED_PIN, HIGH); // turn on } else if (motionStatePrevious == HIGH && motionStateCurrent == LOW) { // pin state change: HIGH -> LOW Serial.println("Motion stopped!"); digitalWrite(LED_PIN, LOW); // turn off } }

Quick Steps

  • Connect Arduino to PC via USB cable
  • Open Arduino IDE, select the right board and port
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Arduino IDE Upload Code
  • Move your hand in front of sensor
  • See the change of LED's state

Code Explanation

Read the line-by-line explanation in comment lines of source code!

Motion Sensor and LED on Commercial Products

  • Light Bulb with Motion Sensor
  • Motion Sensor Alarm
  • TP-Link AC1750 Smart WiFi Router - Dual Band Gigabit Wireless Internet Routers
  • Gaming Keyboard and Mouse

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