The circuit uses a SC16C650 to implement an IrDA interface. Infrared Data Association (IrDA) has defined a group of short-range, high speed, bidirectional wireless infrared protocols, generically referred to as IrDA.
The hardware section is composed of SC16C650 which is electrically hooked-up to an IrDA transceiver module. The electrical connection between the SC16C650 and an IrDA transceiver module is very straightforward, no external component is required except an inverter to invert the IrDA output signal. Besides the power supply noise-filtering components, the only other component required is a 14 Ω resistor. This resistor sets the current through the IR emitter, hence the power output of the transceiver.
IrDA Interface for Portable Devices – [Link]