ESP32 - Touch Sensor - Relay

This tutorial instructs you how to use ESP32 to control LED based on the state of the touch sensor. In detail:

If a touch sensor is being touched, ESP32 activates a relay
If a touch sensor is NOT being touched, ESP32 deactivates a relay

We also have another tutorial: ESP32 - Touch Sensor Toggles Relay, which toggle relay's state between ON and OFF when the touch sensor is touched.

We can extend this tutorial to use the touch sensor to control a led strip, siren, light bulb, or motor... by connnecting them to the relay.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	Micro USB Cable
1	×	Touch Sensor
1	×	Relay
1	×	(Optional) Solenoid Lock
1	×	(Optional) 12V Active Buzzer
1	×	(Optional) 12V Cooling Fan
1	×	(Optional) 12V Warning Light Bright Waterproof
1	×	12V Power Adapter
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Optional) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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Introduction to Relay and Touch Sensor

We have specific tutorials about relay and touch sensor. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

ESP32 Code

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-touch-sensor-relay */ #define TOUCH_SENSOR_PIN 16 // ESP32 pin GPIO16 connected to touch sensor's pin #define RELAY_PIN 26 // ESP32 pin GPIO26 connected to relay's pin void setup() { Serial.begin(9600); // initialize serial pinMode(TOUCH_SENSOR_PIN, INPUT); // set ESP32 pin to input mode pinMode(RELAY_PIN, OUTPUT); // set ESP32 pin to output mode } void loop() { int touchState = digitalRead(TOUCH_SENSOR_PIN); // read new state if (touchState == HIGH) { Serial.println("The sensor is being touched"); digitalWrite(RELAY_PIN, HIGH); // turn on } else if (touchState == LOW) { Serial.println("The sensor is untouched"); digitalWrite(RELAY_PIN, LOW); // turn off } }

Quick Instructions

If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
Do the wiring as above image.
Connect the ESP32 board to your PC via a micro USB cable
Open Arduino IDE on your PC.
Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
Copy the above code and paste it to Arduino IDE.
Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE

Touch and keep touching the touch sensor several seconds
See the change of relay's state

Line-by-line Code Explanation

The above ESP32 code contains line-by-line explanation. Please read the comments in the code!

Video Tutorial

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