Lpc2000

Robert Wood wrote:
>  >> What is the max required uart bit rate? <<
> 
> For the third UART I could get away 9600baud.
> 

YMMV, but the MAX3100 style of device always looks like a CPU that I can't 
access & so I end up using a CPU that I can access instead...  Less cost, better 
availability, more package options. Have to write handler code either way.

That is one extra UART on a similar sized chip & at less cost. The beauty is 
that now you have a dedicated protocol handler which has on-board FIFO's,  and 
so the interrupt loading is less on the main CPU. Not to mention putting the 
main system to sleep & just running the slave CPU to listen for a wakeup on the 
network.

There is code floating about that will allow you to bit bash serial ports on an 
AVR very efficiently, this can provide a bunch of extra lower speed ports for 
interface to GPS & similar. Effectively the CPU treats the UART channels as a 
bunch of parallel shift registers & clocks the parallel byte in and out of the 
device at a multiple of the UART bit rate.

Cheers

Don