ESP32 - Potentiometer Triggers LED

In a previous tutorial, We have learned how to change the brightness of LED according to the potentiometer's output value. In this tutorial, We are going to learn how to:

Hardware Required

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×Potentiometer
1×LED
1×220 ohm resistor
1×Breadboard
4×Jumper Wires
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About LED and Potentiometer

If you do not have knowledge of LED and potentiometer (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 Potentiometer LED Wiring Diagram

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ESP32 Code - Analog Threshold

/* * Created by esp32io.com * * This example code is in the public domain * * Tutorial page: https://esp32io.com/tutorials/esp32-potentiometer-triggers-led */ // constants won't change const int POTENTIOMETER_PIN = A0; // ESP32 pin connected to Potentiometer pin const int LED_PIN = 21; // ESP32 pin GIOP21 connected to LED's pin const int ANALOG_THRESHOLD = 500; void setup() { pinMode(LED_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(LED_PIN, HIGH); // turn on LED else digitalWrite(LED_PIN, LOW); // turn off LED }

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
  • Arduino IDE Upload Code
  • Rotate the potentiometer
  • See the change of LED's state

Code Explanation

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

ESP32 Code - Voltage Threshold

Potentiometer's analog value is converted to voltage value, and then compared to voltage threshold to triggers LED

/* * Created by esp32io.com * * This example code is in the public domain * * Tutorial page: https://esp32io.com/tutorials/esp32-potentiometer-triggers-led */ // constants won't change const int POTENTIOMETER_PIN = A0; // ESP32 pin connected to Potentiometer pin const int LED_PIN = 21; // ESP32 pin GIOP21 connected to LED's pin const float VOLTAGE_THRESHOLD = 2.5; // Voltages void setup() { pinMode(LED_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(LED_PIN, HIGH); // turn on LED else digitalWrite(LED_PIN, LOW); // turn off LED } 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; }

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