Infrared radiation is an electromagnetic radiation which has frequency range between 1 and 430 THz. It’s an ideal way for line-of-sight communications over low to moderate range. They are very popular in line follower, grid follower robots. They also lack interference and even provide freedom to FCC regulation. People at Cornell University explain how to use infrared technology with the popular AVR microcontrollers. The article explains how to use IR remote control to send ascii serial data in a simple fashion. The transmitter drive uses a clever method to modulate and invert the serial output from the USART transmitter. However the circuit was modified in order to improve range at the cost of drawing more current.
The Infrared Emitter used was TSAL6400 which can sustain 100MA of forward current but however due to microcontrollers, current rating of 30MA, the current has to be made limited. For the IR receiver TSOP34156 was used as it has reasonable data rate, minimal burst timing requirement and a good sustained data characteristic. The system works amazingly at 4800 baud rate with 5 characters of overhead. However on increasing the baud rate, the packet rate also increases.