LED Brightness Control with Potentiometer using ESP32 DOIT DevKit v1

Introduction

An LED can be turned ON or OFF using a digital pin, but controlling its brightness requires PWM (Pulse Width Modulation). The ESP32 supports PWM on almost all GPIOs, which makes it easy to adjust LED brightness smoothly.

In this tutorial, we’ll use a potentiometer (GPIO 34) to control the brightness of an LED (GPIO 12). Turning the potentiometer knob will increase or decrease the LED brightness.

Components Required

• ESP32 DOIT DevKit v1
• Potentiometer (10kΩ)
• LED
• 220Ω resistor (to protect LED)
• Breadboard and jumper wires
• USB cable

Circuit Diagram

• Potentiometer VCC → 3.3V
• Potentiometer GND → GND
• Potentiometer Wiper (middle pin) → GPIO 34
• LED + (anode) → GPIO 12 (through 220Ω resistor)
• LED – (cathode) → GND

Arduino Code

// LED Brightness Control with Potentiometer using ESP32 DOIT DevKit v1
// Potentiometer at GPIO 34, LED at GPIO 12

int potPin = 34;   // Potentiometer input pin
int ledPin = 12;   // LED output pin
int potValue = 0;  // Variable to store potentiometer value
int ledValue = 0;  // Mapped value for LED brightness

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  potValue = analogRead(potPin);          // Read potentiometer (0–4095)
  ledValue = map(potValue, 0, 4095, 0, 255); // Map to 0–255 for PWM duty cycle
  
  analogWrite(ledPin, ledValue); // Set LED brightness
  Serial.print("Pot Value: ");
  Serial.print(potValue);
  Serial.print(" | LED Brightness: ");
  Serial.println(ledValue);

  delay(100);
}

Step-by-Step Code Explanation

Define Pins and Variables

int potPin = 34;
int ledPin = 12;
int potValue = 0;
int ledValue = 0;

Assign GPIO 34 for potentiometer input, GPIO 12 for LED output.

Setup

Serial.begin(115200);
pinMode(ledPin, OUTPUT);

Start Serial communication and configure LED pin as output.

Read Potentiometer

potValue = analogRead(potPin);

Reads potentiometer value (range 0–4095).

Map Pot Value to LED Brightness

ledValue = map(potValue, 0, 4095, 0, 255);

Maps potentiometer values (0–4095) to PWM range (0–255).

Set LED Brightness

analogWrite(ledPin, ledValue);

Controls LED brightness based on potentiometer position.

Serial Monitor Debugging

Serial.print("Pot Value: ");
Serial.print(potValue);
Serial.print(" | LED Brightness: ");
Serial.println(ledValue);

Displays both raw potentiometer and mapped LED values.

Output

• Open Serial Monitor → See potentiometer values and mapped brightness.
• Rotate knob left → LED gets dimmer.
• Rotate knob right → LED gets brighter.

Real-Life Applications

• Light Dimmer Switch – control LED or bulb brightness.
• Fan Speed Control – adjust motor speed with potentiometer.
• Audio Control – change sound volume in DIY projects.
• IoT User Interface – physical knob to adjust settings.

Troubleshooting

Problem	Cause	Solution
LED always ON	Wrong wiring	Check LED polarity + resistor
LED doesn’t change brightness	Wrong pin	Ensure LED is on GPIO 12
Values unstable	Loose potentiometer wires	Secure breadboard connections
Serial Monitor garbage	Wrong baud rate	Set 115200 baud