ESP32 - Touch Sensor Toggle Relay

In a previous tutorial, We have learned how to turn on the relay if the touch sensor is touched, and turn off relay if the touch sensor is released. In this tutorial, We are going to learn how to toggle relay each time touch sensor is touched.

By connecting relay to light bulb, led strip, motor or actuator... We can use the touch sensor to toggle light bulb, led strip, motor or actuator...

Hardware Required

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×Touch Sensor
1×Relay
1×Warning Light Bright Waterproof
1×12V Power Adapter
n×Jumper Wires
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About Relay and Touch Sensor

If you do not have knowledge of relay and touch sensor (pinout, how they work, how to connect them to ESP32, how to program for them...), learn about them in the following tutorials:

Wiring Diagram

ESP32 Touch Sensor Relay Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

ESP32 Code - Touch Sensor Toggles Relay

/* * Created by esp32io.com * * This example code is in the public domain * * Tutorial page: https://esp32io.com/tutorials/esp32-touch-sensor-toggle-relay */ // constants won't change const int TOUCH_SENSOR_PIN = 22; // ESP32 pin GIOP22 connected to touch sensor's pin const int RELAY_PIN = 27; // ESP32 pin GIOP27 connected to relay's pin // variables will change: int relayState = LOW; // the current state of relay int lastTouchState; // the previous state of touch sensor int currentTouchState; // the current state of touch sensor 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 currentTouchState = digitalRead(TOUCH_SENSOR_PIN); } void loop() { lastTouchState = currentTouchState; // save the last state currentTouchState = digitalRead(TOUCH_SENSOR_PIN); // read new state if(lastTouchState == LOW && currentTouchState == HIGH) { Serial.println("The sensor is touched"); // toggle state of relay relayState = !relayState; // control relay arccoding to the toggled state digitalWrite(RELAY_PIN, relayState); } }

Quick Steps

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE
  • Connect the ESP32 board to your PC via a micro USB cable
  • Open Arduino IDE, select the right ESP32 board and COM port
  • Copy the above code and paste it to Arduino IDE
  • Click Upload button on Arduino IDE to compile and upload code to ESP32 board
  • Keep touching the touch sensor several seconds and then release it.
  • See the change of relay's state

Code Explanation

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

In the code, relayState = !relayState is equivalent to the following code:

if(relayState == LOW) relayState = HIGH; else relayState = LOW;

Video Tutorial

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