Arduino - Motion Sensor - LED
We are going to learn how to use Arduino to turn on/off the LED according to the motion detection from the HC-SR501 motion sensor:
- If the motion is detected, turn LED on
- If the motion is not detected, turn LED off
Hardware Required
Or you can buy the following kits:
| 1 | × | DIYables STEM V3 Starter Kit (Arduino included) | |
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some links direct to products from our own brand, DIYables .
Additionally, some links direct to products from our own brand, DIYables .
Buy Note: To simplify the wiring process, we recommend using the LED Module, which comes with a built-in resistor.
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
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 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
- 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!
Video Tutorial
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