Oscillator frequency

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:12am

also Anyone know the frequency of crystal oscillator for pic16f877?

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:12am

Have you looked at page 61 and 62 of the PiC16 datasheet, looks like a pretty comprehensive guide for what you are trying to do, frequency is selected by writing to the PR2 register and PS register it seems, haven't done this myself though, don't take my word for it.

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:12am

PR2 doesnt handle the crystal oscillator frequency, it acts as a stop--count-mark for counter of PWM

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:12am

 check IRCF<0:2> in OSCCON (for pic18)

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:12am

 If you are talking about the actual frequency of the oscillator, I'm pretty sure that's a physical property of the crystal oscillator, and can't be changed, PR2 changes PWM period, which is equivalent to changing frequency, I guess that's not what you want?

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:12am

 pic16 QAQ

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Permalink Reply by Kenny Kim on May 1, 2014 at 5:13am

and PR2 cant change to anything lower than 244Hz

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