One of the earliest methods of wireless transmission used was with infrared light. Using wireless IR links has many advantages with the primary two being low cost and low part count to implement. The simplest of on/off switches using wireless IR would take no more than 10 parts, but this tutorial will be going to send asynchronous serial data over a wireless IR link.
This tutorial will create a wireless infrared transmitter using an IR LED and a wireless IR receiver using a phototransistor. Asynchronous serial will be transmit over this link at 9600 BPS. The PIC 18F452 will be used to transmit and receiver this data.
Wireless Infrared Link - [Link]