Linux Infrared HOWTO
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# 3.16. Connection to Keyboard

The Linux/IrDA keyboard driver is now in user-space. Please see chapter Connection to Docking Station above.

Lichen Wang: "The so called IrDA-D standard is designed to transfer Data. It is not suitable for IR Keyboard. IrDA-D is what Dag ported to Linux OS and what MS ported to Windows OS.

The so called IrDA-C (Control) is designed for Keyboard, Joy-stick, etc. I am not aware that there is any product in the market that is using it yet.

IrDA-D cannot talk to IrDA-C. IrDA-C cannot talk to IrDA-D either. Both the physical encoding/decoding and the software protocol are very different.

It is possible to implement both IrDA-D and IrDA-C in the same device. Sharp says that IrDA-D and IrDA-C can coexist -- as long as both of them are not used at the same time in the same IR space. This sounds rather funny to me. According to this definition, anything can co-exist with anything as long as you do not destroy the universe permanently in the process ;-)

Seriously, what SHARP says is that they can tailor the IrDA-D so that there are some unused time between the negotiated maximum turnaround time and the actual transmission. They then squeeze the IrDA-C frames in those unused time. The IrDA-D Primary and IrDA-C Master must be implemented in the same device. The keyboards will work, but mice and joysticks may be sluggish at times."

For details about using external keyboards with Linux PDAs, see the PDA chapter below.

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