External oscillator for PIC32MK

External oscillator for PIC32MK

Postby perdrix » Thu Jun 09, 2022 11:14 am

I was planning to use a crystal, but have been persuaded to use an external oscillator module instead.

I'm looking at the ECS-3225SMV which is available in a range of frequencies between 8MHz and 60MHz.

The datasheet for the PIC32MK0512MCJ064-E/PT says the External Clock frequency can be up to 64MHz.

My question is what is the preferred frequency for an external clock to use with one of these (assuming no other considerations)?

If the answer it "it depends", then guidance on choosing the right frequency will be very helpful.

Thanks
David
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Re: External oscillator for PIC32MK

Postby AussieSusan » Fri Jun 10, 2022 3:33 am

"It Depends"
You need to look at what other uses there are for the system oscillator (ADC sampling frequencies, timers, USB etc.) and see what they need.
Then look at whether you need a PLL involved as well, remembering that it can add a bit if 'jitter' if the oscillator frequency has tight tolerances (e.g. USB, UART).
That will then give you a good idea of the external clock frequency.
Unless you need a temperature controlled oscillator, why is a crystal not good enough?
Susan
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