> An IR data stream from a dedicated IR transmitter IC will have
> a pretty accurate data clock.

Not in my experience. They tend to be RC based and will drift a fair
amount. There is measurable drift over the length of a transmission
but not enough to cause too much trouble.

You also have to watch the rise and fall times of some IR
detectors. They aren't the same so measuring a pulse width gives
you wrong information, but edge to edge is OK.

The method I used recently was to use a single edge interrupt and
each timen preload a timer with 0xff minus the value halfway
between a 0 and 1 bit time. Each time you get an edge interrupt,
the data bit to record is the value of the timer overflow flag.

Steve.

======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: steveb@tla.co.nz      fax +64 9 820-1929
======================================================

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