Arduino UNO R4 - Potentiometer fade LED

This tutorial instructs you how to program the Arduino UNO R4 to control the brightness of an LED based on the output value of a potentiometer.

Arduino UNO R4 potentiometer fade LED

Hardware Preparation

1×Arduino UNO R4 WiFi
1×Arduino UNO R4 Minima (Alternatively)
1×USB Cable Type-C
1×220 ohm resistor
1×Jumper Wires
1×(Optional) 9V Power Adapter for Arduino UNO R4
1×(Recommended) Screw Terminal Block Shield for Arduino Uno
1×(Optional) Transparent Acrylic Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1×DIYables Sensor Kit (30 sensors/displays)
1×DIYables Sensor Kit (18 sensors/displays)
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Overview of LED and Potentiometer

Learn about LED and potentiometer (pinout, functionality, programming) in the tutorials provided:

Wiring Diagram

The wiring diagram between Arduino UNO R4 Rotary Potentiometer LED

This image is created using Fritzing. Click to enlarge image

How To Program

  • Reads the input on the analog pin A0 (value ranges from 0 to 1023)
int adc_value = analogRead(A0);
  • Convert it to a brightness level (a number from 0 to 255)
int brightness = map(adc_value, 0, 1023, 0, 255);
  • Sets the brightness of the LED connected to pin 3.
analogWrite(LED_PIN, brightness);

Arduino UNO R4 Code

/* * This Arduino UNO R4 code was developed by * * This Arduino UNO R4 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * */ #define LED_PIN 3 // The Arduino UNO R4 pin connected LED #define POTENTIOMETER_PIN A0 // The Arduino UNO R4 pin connected potentiometer void setup() { // initialize serial communication at 9600 bits per second: Serial.begin(9600); // declare LED pin to be an output: pinMode(LED_PIN, OUTPUT); } void loop() { // reads the input on analog pin A0 (value between 0 and 1023) int adc_value = analogRead(POTENTIOMETER_PIN); // scales it to brightness (value between 0 and 255) int brightness = map(adc_value, 0, 1023, 0, 255); // sets the brightness LED that connects to pin 3 analogWrite(LED_PIN, brightness); // print out the value Serial.print("Analog: "); Serial.print(adc_value); Serial.print(", Brightness: "); Serial.println(brightness); delay(100); }

Detailed Instructions

Follow these instructions step by step:

  • If this is your first time using the Arduino Uno R4 WiFi/Minima, refer to the tutorial on setting up the environment for Arduino Uno R4 WiFi/Minima in the Arduino IDE.
  • Wire the components according to the provided diagram.
  • Connect the Arduino Uno R4 board to your computer using a USB cable.
  • Launch the Arduino IDE on your computer.
  • Select the appropriate Arduino Uno R4 board (e.g., Arduino Uno R4 WiFi) and COM port.
  • Copy the code and open it in Arduino IDE
  • Click the Upload button in Arduino IDE to upload the code to Arduino UNO R4
  • Open the Serial Monitor
  • Turn the potentiometer
  • Observe the LED
  • Check the result on the Serial Monitor
Analog: 6, Brightness: 1 Analog: 34, Brightness: 8 Analog: 89, Brightness: 22 Analog: 149, Brightness: 37 Analog: 214, Brightness: 53 Analog: 297, Brightness: 74 Analog: 365, Brightness: 90 Analog: 431, Brightness: 107 Analog: 510, Brightness: 127 Analog: 589, Brightness: 146 Analog: 695, Brightness: 173 Analog: 790, Brightness: 196 Analog: 970, Brightness: 241 Analog: 996, Brightness: 248 Analog: 1018, Brightness: 253 Analog: 1023, Brightness: 255
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