The HC-SR04 sensor makes it possible to measure wirelessly the distance that separates it from a given obstacle. We will use this capability to build a bargraph that will alarm you if you approach a wall in order to avoid it.
For more about this sensor please check the show-case here .
VIDEO : Obstacle avoider tutorial
In order to realize this project you will need the following components :
5mm colored LEDs
220 Ohm (or >) Resistors