At 07:50 PM 05/11/2001 -0500, you wrote:
>At 08:40 AM 11/6/01 +1300, you wrote:
>>Hi all,
>>still battling with this serial coms.
>>
>>Question: do I have to use a proper xtal (metal can type) for accurate timing
>>for serial communication, or is a ceramic resonator adequate?
>
>Ceramic resonator (at least up to 10 MHz) will work fine.

I have some units running a 16F628-20 with a 20MHz 3 pin resonator
reliably at 9600 baud. Check the specs for the resonator. From memory
you need the oscillator to be within about 2-3% of the correct frequency
assuming 8N1 type async comms. (10 bits all up) It makes no difference
what the baud rate is - only the relative percentage so you don't end up
testing the received bit levels right at the edges of each bit. Any error you
have will accumulate over the byte but will reset at the start of new one.
Regards...

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