LED Bar Graph

Components Used:

  • 1x Breadboard
  • 1x Arduino Uno R3
  • 1x 5k ohm variable resistor (potentiometer)
  • 2x Jumper
  • 8x LEDs
  • 8x 330Ω Resistor


LED Bar Graph



Program by: Ankit Modi
 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 8LEDs, 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.
// these constants won't change:
const int analogPin = A0; // the pin that the potentiometer is attached to
const int ledCount = 8; // the number of LEDs in the bar graph

int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9}; // 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:
 digitalWrite(ledPins[thisLed], LOW);