LED Bar Graph

The bar graph - 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, like this one. This tutorial demonstrates how to control a series of LEDs in a row, but can be applied to any series of digital outputs.

This tutorial borrows from the For Loop and Arrays tutorial as well as the Analog Input tutorial.

A bar graph display

Hardware Required

  • Arduino or Genuino Board
  • LED bar graph display or 10 LEDs
  • Potentiometer
  • 10 220 ohm resistors
  • hook-up wires
  • breadboard

Circuit

click the image to enlarge

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Schematic:

click the image to enlarge

Code

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.

See Also:


Last revision 2015/07/28 by SM