Arduino - 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×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
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 know about relay and touch sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino Touch Sensor Relay Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Arduino Code - Touch Sensor Toggles Relay

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-touch-sensor-toggle-relay */ // constants won't change const int TOUCH_SENSOR_PIN = 7; // Arduino pin connected to touch sensor's pin const int RELAY_PIN = 3; // Arduino pin 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 arduino pin to input mode pinMode(RELAY_PIN, OUTPUT); // set arduino 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

  • 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
  • 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;

Touch Sensor and Relay on Commercial Products

  • Touch Control Table Lamp
  • Touch Kitchen Faucets
  • Touch Control Table Lamp with Wireless Charger and USB Charging Port
  • Gaming Keyboard and Mouse
  • Wemo Smart Plug, WiFi Enabled, Works with Alexa, Google Assistant & Apple HomeKit

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