> Anyway, if I understand correctly, you set a timer for some value
> smaller than the length of a bit, then sample the pic every interrupt
> right? But what if my timer interrupt lands right on a port change or
> something? Also I don't understand the INTF statement.

Well, first you need to know the format and timing of the data
coming in. If it's a regulary timed data stream (ie the same length
for a "0" or "1") then the convention is to sample each bit at least
three times, although if you're confident about the timing at both
ends (Tx and Rx) you could sample just once, right in the middle
of the bit. This does leave you open to errors though

To keep it simple, say a data bit length is 6ms and you want to
sample each bit 3 times. After the first edge detection (which is
where INTF comes into it), you wait for 1ms, sample, wait 2ms,
sample, wait 2ms, sample. You have then got 3 equi-distant
samples, (at 1ms, 3ms and 5ms) which if you have to, can be
checked for a majority decision in the case of a noisy environment or
if you just want to be absolutely sure. Many micros sample 16 or
more times per bit and then get a majority decision. Getting the PIC's
code timing in synch with the data stream should mean that nothing
unexpected will happen whilst you are sampling. If the data is that
important, it should be given the highest priority you can

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