ESP32 - Potentiometer Triggers Relay

This tutorial instructs you how to use ESP32 with the potentiometer to control relay. In detail:

We also learn how to convert the analog value to voltage and then use the voltage threshold to control relay:

We can extend this tutorial to use button 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×Potentiometer
1×Relay
1×Warning Light Bright Waterproof
1×12V Power Adapter
n×Jumper Wires
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Introduction to Relay and Potentiometer

We have specific tutorials about relay and potentiometer. 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

wiring diagram between esp32 potentiometer relay

This image is created using Fritzing. Click to enlarge image

ESP32 Code - Analog Threshold

/* * 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-potentiometer-triggers-relay */ #define POTENTIOMETER_PIN 4 // ESP32 pin GIOP4 (ADC10) connected to Potentiometer pin #define RELAY_PIN 27 // ESP32 pin GIOP27 connected to Relay's pin #define ANALOG_THRESHOLD 1000 void setup() { pinMode(RELAY_PIN, OUTPUT); // set ESP32 pin to output mode } void loop() { int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin if (analogValue > ANALOG_THRESHOLD) digitalWrite(RELAY_PIN, HIGH); // turn on Relay else digitalWrite(RELAY_PIN, LOW); // turn off Relay }

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
  • Arduino IDE Upload Code
  • Rotate the potentiometer
  • 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!

ESP32 Code - Voltage Threshold

The analog value read from the potentiometer is converted to voltage, and then the voltage is compared to a voltage threshold. If it exceeds the threshold, it triggers relay

/* * 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-potentiometer-triggers-relay */ #define POTENTIOMETER_PIN 4 // ESP32 pin GIOP4 (ADC10) connected to Potentiometer pin #define RELAY_PIN 27 // ESP32 pin GIOP27 connected to Relay's pin #define VOLTAGE_THRESHOLD 2.5 // Voltages void setup() { pinMode(RELAY_PIN, OUTPUT); // set ESP32 pin to output mode } void loop() { int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin float voltage = floatMap(analogValue, 0, 1023, 0, 5); // Rescale to potentiometer's voltage if(voltage > VOLTAGE_THRESHOLD) digitalWrite(RELAY_PIN, HIGH); // turn on Relay else digitalWrite(RELAY_PIN, LOW); // turn off Relay } float floatMap(float x, float in_min, float in_max, float out_min, float out_max) { return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min; }

Video Tutorial

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