From: John Lawton <piclist@jle.co.uk>
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Date: Tue, 20 Oct 2020 10:00:06 -0700
Subject: Re: [PIC] Crystal frequency selection
Thread-Topic: [PIC] Crystal frequency selection
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But you didn't, it's all there is the datasheets :)

John

On 20/10/2020 17:34, Neil wrote:
> Okay, I found one... 14.7456Mhz crystal --> 59.9824Mhz Fosc, which is
> close enough to 64Mhz.
> Using SPBRG =3D 127 with that gives me spot-on 115,200 baud (so 0% error)=
..
> And there are 10+ suppliers for 3.2 x 2.5mm SMD crystals with that
> frequency so that's common enough to be low-cost and not have to worry
> about being discontinued in the near future.
> Wish I didn't have to trial and error this though.
>
> Cheers,
> -Neil.
>
>
>
>
>
> On 10/20/2020 12:27 PM, Neil wrote:
>> I had also created my own, but it's been trial-and-error (xtal freq
>> and SPBRG value) to find a spot-on crystal.
>> Now, if your spreadsheet runs through DIgikey's crystal frequency
>> selections and picks the spot-on option for me, then you have my
>> attention :)
>>
>> Cheers,
>> -Neil.
>>
>>
>>
>> On 10/20/2020 12:08 PM, Nicola Perotto wrote:
>>> Hi Neil & all,
>>> I use the attached spreadsheet to calculate baud and errors.
>>> Enter values in yellow cells.
>>>        N
>>>
>>>
>>> On 20/10/2020 16:42, Neil wrote:
>>>> A bit academic, but this is bugging me... I was trying to get as close
>>>> to 115,200 baud on a PIC18F running at 64Mhz (or thereabouts).
>>>> At 64Mhz, best I can get is 0.8% error using SPBRG=3D34.
>>>> Calculating backwards, to get exactly 115,200, I can't find an "exact"
>>>> crystal.
>>>> Shouldn't I be able to find one of those "odd" values to get exactly
>>>> 115,200 baud at around 64Mhz?
>>>>
>>>> Cheers,
>>>> -Neil.
>>>>
>>>
>>>

--=20
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