At 10:56 AM 11/27/2003 -0500, you wrote:
>I have been playing with Microchip's PICkit 1 and the 12F675 8-Pin PIC.  I
>have been using the internal RC oscillator, as it keeps the number of
>external parts down, which keeps the playtime with the PIC up.  I have
>downloaded and read the documentation on the device and am confused by
>trying to figure out what the clock cycle time is.
>
>What I think I know;
>
>-The documentation says that the minimum cycle time is 200nS which is a
>5MHz Clock
>     -a 20MHz crystal used an external oscillator, would be divided by 4,
> in fact any external oscillator would be divided by 4
>-the internal RC oscillator runs at ~4MHz, within 1% accuracy when calibrated.
>     -the internal oscillator is not divided by 4, thus instruction cycle
> time is 250nS
>
>Is this correct?  I understand some instructions may take 2 cycles to
>run.  Loops I have made appear to support that the internal RC oscillator
>is not divided by 4, but the documentation is not clear on this.

It's divided by 4, so 1us Tcy using the internal RC clock on the
aforementioned part.

Where the data sheet seems to offer insufficient information, you should
be checking the midrange reference manual. Usually it's there.

Best regards,

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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