How to Use IR LED and Photodiode with Arduino

      In this post I am going to show you how to use and program IR LED and Photodiode pair with Arduino to detect obstacles in a short range. Before going to do the project let us have a brief look at the IR LED and Photodiode.

IR LED:

                   IR LED means Infrared Light Emitting Diode. The IR LED emits Infrared light which is not visible to human eye. we can find these IR LED's in our TV Remotes. IR LED's works like normal LED's but the material used in the core is different, it emits Infrared Light when current passed through it. These IR LED are used to detect obstacles ahead of the robot. The IR LED emits IR light which gets reflected if any obstacle is present in the direction of emitted IR ray, the reflected IR ray caught by Photodiode which calculates the reflected light strength. The higher the reflected IR
ray strength, the closer is the obstacle and vice-verse

Photodiode:

                  Photodiode is a light sensitive semi-conductor diode which converts the light energy into voltage or current based on the mode of operation. In general Photodiodes are operated in reverse bias condition. The clear Photodiode can detect visible and IR rays to limit the Photodiode to detect only IR rays a black cotting is applied to the glass of the Photodiode. The photodiode allows the current to pass through it if the photodiode is exposed to IR rays and it doesn't allow current to pass through it if no IR rays falls on it. The amount of current passed through the photodiode is directly proportional to amount of IR rays falls on it.

IR LED and Photodiode Project:

                  In this project I am going to show you How to use the IR LED and Photodiode pair to detect the obstacle in-fornt of it. I am going to program the Arduino such that, If an obstacle is present before the IR LED and Photodiode pair with in the threshold range then a buzzer will ring.