LED Brightness Control Using Arduino and Potentiometer

Hello friends! Welcome back to ElectroDuino. This is the Arduino Tutorial #7 – LED Brightness Control Using Potentiometer. After understanding Arduino AnalogRead using Potentiometer in the Arduino Tutorial #6. In this blog, we going to describe the Project concept, What is the map in Arduino, LED Brightness Control Using the Potentiometer circuit diagram, and Arduino Code/sketch.

Project Concept of LED Brightness Control

In this project, we will control LED brightness using the Potentiometer. This project concept is based on the “Arduino AnalogRead using the Potentiometer” and “Digital pin PWM output | Arduino LED Fading“, which is explained in the previous tutorials. Here we will read analog output from the potentiometer using Arduino and control the LED using PWM output. Also, use the map( ) function in the Arduino code.

Components Required

Analog input read from the potentiometer 

First of all, we need to connect the Potentiometer terminal 1 is connected to +5v Vcc, and terminal 3 is connected to the ground. Now we can read the output from terminal 2 of the potentiometer, and we need to connect this terminal to an analog pin of the Arduino board. Arduino analog pin has 10-bit Analog to Digital Converter(ADC), which converts the potentiometer output voltage into integer value between the range of 0 to 1023 volts (2^10 = 1024) as input. Where the value “0” represents “0 volts” and the value “1023” represents “5 volts”. When we will Rotate the potentiometer knob, then the output voltage is changed and the Arduino reads this change of output voltage as the input voltage.

Digital output on the LED

Another side, the positive terminal of the LED is connected to the PWM(Pulse Width Modulation) pin. This pin provides analog results with digital means at the range of 0 to 255. Where the value “0” represents “0 volts” and 255 represents “5 volts”. The LED brightness changes from Low to High according to the change of the PWM output value from 0 to 255.

In this project, we will change the LED brightness by rotating the potentiometer knob. We will increase and decrease the LED brightness value between 0 to 255 according to the changing potentiometer output value between 0 to 1023. When the potentiometer output value is 0 then the LED input value is 0 and the LED brightness is LOW (off). When the potentiometer output value is 1023 then the LED input value is 255 and the LED brightness is High. This graph represents how output voltage is increased or decreased according to the potentiometer output voltage. To work this operation we need to use a function called map() in Arduino Code.

What is the map( ) Function in Arduino Code

Re-maps a number from one range to another. That is, a value of fromLow would get mapped to toLow, a value of fromHigh to toHigh, values in-between to values in-between, etc.

Note that the “lower bounds” of either range may be larger or smaller than the “upper bounds” so the map() function may be used to reverse a range of numbers, for example

y = map(x, 1, 50, 50, 1);

The function also handles negative numbers well, so that this example

y = map(x, 1, 50, 50, -100);

is also valid and works well.

Syntax

map(value, fromLow, fromHigh, toLow, toHigh)

Parameters

• value: the number to map.
• fromLow: This is the lower bound of the input voltage range.
• fromHigh: It is the upper bound of the input voltage range.
• toLow: This is the lower bound of the output voltage range.
• toHigh: It is the upper bound of the output voltage range.

LED Brightness Control Using Potentiometer Circuit diagram / Schematic

Circuit Wiring

LED Brightness Control Using Potentiometer Code/sketch

/*
Arduino Tutorial #7 - LED Brightness Control Using Potentiometer
http://www.electroduino.com
*/

const int analogInPin = A0;
const int analogOutPin = 6;

int sensorValue = 0;
int outputValue = 0;

void setup()
{
Serial.begin(9600);
}

void loop() {

sensorValue = analogRead(analogInPin);

outputValue = map(sensorValue, 0, 1023, 0, 255);


analogWrite(analogOutPin, outputValue);

Serial.print("sensor = ");
Serial.print(sensorValue);
Serial.print("\t output = ");
Serial.println(outputValue);

delay(2);
}

Code Analysis

Output Result

As a result, you can see LED brightness change according to the rotation of the potentiometer knob.

The map( ) Function data Content Credit: map() – Arduino Reference