At 06:31 PM 5/2/2003 +0200, you wrote:

>>I'd consider this (just) acceptable in cases where the other side is
>>guaranteed to have a crystal, for example where the PIC will be
>>communicating with a PC for uploading data or as a calibration/setup
>>port.
>>For communication between two PICs, it is a little too sloppy (and may
>>always be, getting better than 2% accuracy with an analog RC oscillator
>>over all parameters isn't easy)
>
>Beware that even with a Xtal,  frequencies are not exact,
>i.e. hardware usart @ 20Mhz PIC:
>38.4, 57.6, 115.2 kBaud  all have   -1.36% error
>Stef Mientki


1.      The 12F675 internal oscillator is 4.00 MHz nominal (AFAICR, so are
         all calibrated internal RC oscillators in Microchip's line).

2.      There is no internal hardware UART, and no baud-rate generator,
         it's all bit-banged in the 12F675.

3.      *If* there was an F876 style BRG in the 12F675, it could be used
         at 9600 or 19,200 baud settings with negligible 0.16% errors
         (BRGH=1) due to the BRG.


Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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