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.

Hardware Preparation

1	×	Arduino UNO R4 WiFi or Arduino UNO R4 Minima
1	×	Alternatively, DIYables STEM V4 IoT, Compatible with Arduino Uno R4 WiFi
1	×	Alternatively, DIYables STEM V4B IoT, Compatible with Arduino Uno R4 WiFi
1	×	USB Cable Type-A to Type-C (for USB-A PC)
1	×	USB Cable Type-C to Type-C (for USB-C PC)
1	×	Potentiometer
1	×	Alternatively, 10k Ohm Trimmer Potentiometer
1	×	Alternatively, Potentiometer Kit
1	×	Alternatively, Potentiometer Module with Knob
1	×	LED Kit
1	×	LED (red)
1	×	LED Module
1	×	Alternatively, Button and LED Kit
1	×	220Ω Resistor
1	×	Breadboard
1	×	Jumper Wires
1	×	Recommended: Screw Terminal Block Shield for Arduino UNO R4
1	×	Recommended: Sensors/Servo Expansion Shield for Arduino UNO R4
1	×	Recommended: Breadboard Shield for Arduino UNO R4
1	×	Recommended: Enclosure for Arduino UNO R4
1	×	Recommended: Power Splitter for Arduino UNO R4
1	×	Recommended: Prototyping Base Plate & Breadboard Kit for Arduino UNO

Or you can buy the following kits:

1	×	DIYables STEM V4 IoT Starter Kit (Arduino included)
1	×	DIYables STEM V4B IoT Starter Kit (Arduino included)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Buy Note: Use the LED Module for easier wiring. It includes an integrated resistor.

Overview of LED and Potentiometer

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

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

The diagram below shows the same connections without a breadboard:

The wiring diagram between Arduino UNO R4 Rotary Potentiometer LED (No Breadboard)

This image is created using Fritzing. Click to enlarge image

Jumper wires are good for a quick test, but not for a final build. To do that, mount a Proto Screw Terminal Block Shield or a Screw Shield V2 on the Arduino UNO R4. This is how it looks with the Screw Shield V2:

The wiring diagram between Arduino UNO R4 Rotary Potentiometer LED Screw Shield

This image is created using Fritzing. Click to enlarge image

See The best way to supply power to the Arduino Uno R4 and other components.

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 newbiely.com * * This Arduino UNO R4 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-potentiometer-fade-led */ #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

Newbiely | Arduino IDE 2.3.8

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Newbiely.ino

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8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'Arduino Uno R4 WiFi' on 'COM15')

New Line

9600 baud

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

Ln 11, Col 1

Arduino Uno R4 WiFi on COM15

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