SENSORS/ACTUATORS

ESP8266 - Motion Sensor - Relay

This tutorial instructs you how to use ESP8266 and motion sensor to control relay. In detail:

ESP8266 activates the relay when motion is detected
ESP8266 deactivates the relay when motion is not present

By connecting a relay to a light bulb, LED strip, motor or actuator, we can use ESP8266 and a 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

1	×	ESP8266 NodeMCU
1	×	Micro USB Cable
1	×	HC-SR501 Motion Sensor
1	×	Relay
1	×	Warning Light Bright Waterproof
1	×	12V Power Adapter
1	×	DC Power Jack
1	×	Jumper Wires
1	×	(Optional) 5V Power Adapter for ESP8266
1	×	(Optional) ESP8266 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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. We appreciate your support.

Overview of Relay and Motion Sensor

If you are unfamiliar with relay and motion sensor (pinout, functioning, programming ...), the following tutorials can help:

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

See more in ESP8266's pinout and how to supply power to the ESP8266 and other components.

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.

ESP8266 Code

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-motion-sensor-relay */ #define MOTION_SENSOR_PIN D2 // The ESP8266 pin connected to the OUTPUT pin of motion sensor #define RELAY_PIN D7 // The ESP8266 pin connected to Relay's pin 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); // Configure the ESP8266 pin to the input mode pinMode(RELAY_PIN, OUTPUT); // Configure the ESP8266 pin to the 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!, turns relay ON"); digitalWrite(RELAY_PIN, HIGH); // turn on } else if (prev_motion_state == HIGH && motion_state == LOW) { // pin state change: HIGH -> LOW Serial.println("Motion stopped!, turns relay OFF"); digitalWrite(RELAY_PIN, LOW); // turn off } }

Detailed Instructions

To get started with ESP8266 on Arduino IDE, follow these steps:

Check out the how to setup environment for ESP8266 on Arduino IDE tutorial if this is your first time using ESP8266.
Wire the components as shown in the diagram.
Connect the ESP8266 board to your computer using a USB cable.
Open Arduino IDE on your computer.
Choose the correct ESP8266 board, such as (e.g. NodeMCU 1.0 (ESP-12E Module)), and its respective COM port.
Connect your ESP8266 to your computer using a USB cable.
Launch the Arduino IDE, select the correct board and port.
Copy the code and open it in the Arduino IDE.
Click the Upload button in the Arduino IDE to send the code to the ESP8266.

Code Explanation

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

Video Tutorial

Learn More

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