Hello Michael .

> Ideas wanted: PIC-to-PIC comms at speeds greater than 1Mbit/s ?
> The data is in long bursts (typ. 2-3 minutes each 5 minutes).
> I suspect that a hardware UART is the only way to even start considering
> the problem, otherwise there will be no time for anything else in the CPU !
> Also - of course, this is a project that demands huge quantities - so the
> final product will need to be l-o-w cost !
> The good news is that the links will be no more than 500mm long. The bad
> news is that they will be in an electrically noisy environment.

There are some technique to increase of serial data transfer rate .
Every period of carrier frequency "phisically" has two level:
 the '1' level and the '0' level . Every level has also two possible
duration: t1 and t2 . Due to that appear possibility to send
2 "logical" bit at one "phisical" period of carrier .

For example:
"00" combination send as '0'(t1) '1'(t1)
"01" combination send as '0'(t1) '1'(t2)
"10" combination send as '0'(t2) '1'(t1)
"11" combination send as '0'(t2) '1'(t2)

I think there are another possibilities to increase transfer rate.
For example discuss more time interval not only 2 . But i not
practically
discover it .

The main disadvantage of this method is absent harware
transiver/receiver
build in PIC . So it may be implemented only in software .

WBR Dmitry .