Nathan Stewart wrote:

> How do you do multi-channel serial, at different clock rates w/ a PIC?
> My intended application is reading an A/D and a PC keyboard and
> shoving the combined data out an RS-232 port.
> Is this feasible to do in software w/ a pic? Should I just use a
> parallel output ADC and a UART, leaving only the keyboard to software?

  As far as I can see, this represents no problem, certainly nowhere
near the problem of performing multiple RS-232 channels with differing
baudrates.

  The ADC is a slave device, which means that the PIC is at liberty to
determine the timing of transfers.  I honestly can't remember whether
keyboard or PC is master on that link, but am sure there is a way around
it even if keyboard is master.

  RS-232 output is *very* easily managed by an interrupt-driven state
machine because only one interrupt per bit (including start and stop) is
required, unlike receive.  It would otherwise be easy to interleave
RS-232 transmit and I2C transfers without any interrupts, but the PC
keyboard may not be so amenable.

  My thoughts anyway, if that be a guide.

 Cheers,
        Paul B.