Jinx wrote:
>> I have found on the PICs that Ive tried to use the internal osc for
>> UART comm's, its never worked out
>>     
>
> I use the 18F1320 with IntOsc and have the fixed-frequency device
> (an 18F4550) send timing information into Rx. Rx is temporarily
> re-assigned as an I/O that the timer can measure transitions on. The
> 1320 then uses the timer result to re-calibrate itself. The 1320 has
> auto-baud but the drift is generally too minor to bother. It works
> out well for me because I'm in control of the whole thing, and have
> to contend with a 40C temperature range, but you should be able
> to tell any remote device to send an occassional byte for reference
>
>   
I have several commercial designs with PIC16F88 and '87s. Overall it is 
a very nice part, one
of the very best MicroChip has made. In TSSOP form, it is a powerhouse 
while having a tiny
footprint.

My only complaint is that the BOR trigger level cannot be changed, so 
when working with 3.3V
using the LF88,the BOR must be off. Too bad, the BOR is a nice feature 
for ensuring proper
power up.

Of course it is saddled with that annoying LVP pin, so a 10K resistor is 
needed to GND all the
time on that pin.

I've also tinkered with the internal RC with no success as far as using 
it as a baud clock. I'm
of the opinion that the internal oscillator speeds up then slows down; 
while it averages 1%, it
is not stable enough to use as a baud clock. A 4Mhz ceramic resonator is 
very low in cost,
rugged, and quite stable so no harm done.

--Bob


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