Arduino Tutorial #7 – LED Brightness Control Using Potentiometer

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Hello friends! Welcome back to ElectroDuino. This is the Arduino Tutorial #7LED 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

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

Components NameQuantity
Arduino Uno R31
USB cable for Arduino Uno1
10k Potentiometer1
LED1
220Ω Resistor1
Connecting wireAs per required in the circuit diagram

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 change and the Arduino reads this changing of output voltage as the input voltage.

Potentiometer Internal Construction and Symbol
Potentiometer Internal Construction and Symbol

Digital output on the LED

Another side, the positive terminal of the LED 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 Low to High according to the change of PWM output value 0 to 255.

LED (Ledlight Emitting Diode) internal Construction & symbol
LED (Ledlight Emitting Diode) internal Construction & symbol

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.

LED Brightness Control Potentiometer Input vs LED Output Voltage Graph
LED Brightness Control Potentiometer Input vs LED Output Voltage Graph

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

LED Brightness Control Using Potentiometer Circuit Diagram
LED Brightness Control Using Potentiometer Circuit Diagram

Circuit Wiring

Components PinsArduino Pins
Potentiometer terminal 15v pin
Potentiometer terminal 2Arduino analog pin “A0”
Potentiometer terminal 3GND pin
LED positive (+) terminal Connected to Arduino Digital pin “D5” through a 220-ohm resistor.
LED negative (-) terminal Connected to GND pin

LED Brightness Control Using Potentiometer Code/sketch

Code Analysis

Code LineDescription
const int analogInPin = A0;This line is declared your potentiometer output pin connected to Arduino analog pin “A0” and named as analogInPin.
const int analogOutPin = 6;This line is declared your LED positive pin connected to Arduino digital pin 6 and named as analogOutPin.
int sensorValue = 0;
int outputValue = 0;
Define two variables sensorValue and outputValue. At the starting of the code, we set these values at 0.
Serial.begin(9600);This function is used to begin serial communication, at 9600 bits of data per second, between your Arduino board and your computer.
sensorValue = analogRead(analogInPin);This line is the main function of the code. It is used to read output value from the potentiometer and That output value is stored in the “sensorValue” variable in the range between 0 to 1023.
outputValue = map(sensorValue, 0, 1023, 0, 255);output Value is assigned to equal the scaled value from the potentiometer output. The map() function accepts five arguments: The value to be mapped (sensorValue), the low range and high values of the input data (Potentiometer output), and the low and high values for that data to be remapped to the output (LED input). Here, the potentiometer output is mapped down from the range of 0 to 1023 to 0 to 255.
analogWrite(analogOutPin, outputValue);analogWrite is used to provide output to the LED.
Serial.print("sensor = ");
Serial.print(sensorValue);
Serial.print("\t output = ");
Serial.println(outputValue);
Finally, you need to print the sensor (pot) value and output value on your serial monitor window using this command.
delay(2);Wait for 2 milliseconds to see the result clearly.

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

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