Arduino based LED BarGraph || IoT Project


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LED BarGraph:

The LED bargraph – a series of LEDs in a line, such as you see on an audio display – is a common hardware display for analog sensors. It’s made up of a series of LEDs in a row, an analog input like a potentiometer, and a little code in between. You can buy multi-LED bar graph displays fairly cheaply.This tutorial demonstrates how to control a series of LEDs in a row, but can be applied to any series of digital outputs.

Want to know about how to start with Arduino , then check Getting started with Arduino and Arduino IDE

Check first step in IoT project development Arduino base LED-Blink 

Hardware Required:


              • LED bar graph display or 10LEDs
              • Potentiometer
              • Ten – 220 ohm resistors
              • hook-up wires
              • breadboard



LED bargraph-schematic

Image credit: Arduino Bargraph


The sketch works like this: first you read the input. You map the input value to the output range, in this case ten LEDs. Then you set up a for loop to iterate over the outputs. If the output’s number in the series is lower than the mapped input range, you turn it on.If not, you turn it off.


//Arduino LED BarGraph Program 

//This Program will run in Arduino IDE


LED bar graph


Turns on a series of LEDs based on the value of an analog sensor.

This is a simple way to make a bar graph display. Though this graph

uses 10 LEDs, you can use any number by changing the LED count

and the pins in the array.


This method can be used to control any series of digital outputs that

depends on an analog input.


The circuit:

* LEDs from pins 2 through 11 to ground


created 4 Sep 2010

by Tom Igoe


This example code is in the public domain.




// these constants won’t change:

const int analogPin = A0;   // the pin that the potentiometer is attached to

const int ledCount = 10;    // the number of LEDs in the bar graph


int ledPins[] = {

2, 3, 4, 5, 6, 7, 8, 9, 10, 11

};   // an array of pin numbers to which LEDs are attached



void setup() {

// loop over the pin array and set them all to output:

for (int thisLed = 0; thisLed < ledCount; thisLed++) {

pinMode(ledPins[thisLed], OUTPUT);




void loop() {

// read the potentiometer:

int sensorReading = analogRead(analogPin);

// map the result to a range from 0 to the number of LEDs:

int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);


// loop over the LED array:

for (int thisLed = 0; thisLed < ledCount; thisLed++) {

// if the array element’s index is less than ledLevel,

// turn the pin for this element on:

if (thisLed < ledLevel) {

digitalWrite(ledPins[thisLed], HIGH);


// turn off all pins higher than the ledLevel:

else {

digitalWrite(ledPins[thisLed], LOW);






Featured image credit: arduino-bargraph

Information and  project code credit:


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