IrDa page

General introduction to IrDA

One reason for short-range wireless connection is to get rid of a cable between two devices. IrDA implements this kind of short-range wireless connection using infrared. IrDA uses series of infrared pulses to send data. IrDA data modulation uses a maximum 25% duty-cycle return-to-zero pulse to limit power dissipation in the IR emitter. Original IrDA was designed to operate at 115200 bps.

In 1993, 50 companies met to create the IrDA (Infrared Data Association, In 1994, the association published the first IrDA specification, which defined the lower layers of the infrared protocol. Lack of standardization at the upper protocol layers slowed the adoption of IrDA technology. Although most notebook PCs contain an IrDA port, peripheral manufacturers haven't adopted the technology as rapidly as notebook manufacturers.

The chip you use to interface to the IrDA transceiver depends on the functions you have available in your design. If you're using a PC I/O chip, such as National Semiconductor's PC8739x, you can connect an infrared transceiver directly to the chip's IR interface pins. If you have a serial interface available you need to use an IR modulator/demodulator or EnDec (encode/decode) chip. An EnDec chip translates serial data to and from the format that IrDA transceivers require.

The IrDA-protocol code size depends on the functions you want to put into your device. The IrDA publishes a document for a minimal IrDA implementation called IrDA Lite which tells minimal requirements necessary for compatibility with IrDA devices. IrDA Lite implementations range from a device that transfers data at 9600 bps to full-featured IrDA designs.

Microsoft added IrDA support beginning with Windows 95, and today you will find IrDA in Windows 98, ME, and 2000. Windows XP includes additional IrDA support for the VFIR (Very Fast IR) 16-Mbps extension and for USB attached IrDA devices.

General articles

IrDA standards

IrDA circuits

Related pages

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