Lee Mulvogue wrote 2012-09-25 07:48:
>
>
> I'd always read in the past to not use the internal OSC of a PIC as it
> was too innacurate,

Innacurate for *what* ?
I always use INTOSC as long as it is accurate enough.

> but am now wondering if this is still the case for a PIC24F?
>

Impossible to answer.

> I've just started making a board based on a PIC24FJ64GA004 (my first
> time with a 24F), and added the usual 20MHz crystal and supporting caps;
> but are the modern PICs accurate enough to start considering dumping
> this external setup?  The most time sensitive thing I'm doing is
> interrupting @ 16kHz for PCM sound playback (current sample to PWM
> output, set flag for Main loop to process the next sample), and simple
> RS232 comms.  The datasheet seems to indicate a max variation of +/-
> 5%,

That is over the range "-40=B0C -- +125=B0C", right ?

At 25=B0C it's +/- 2%.

Since you give no indications of the temp range where this
processor will be used, you have to decide yourself.

Jan-Erik.


> but I don't have a benchmark to compare that against.
>
> I'd possibly be running the 8Mhz internal with the 4x PLL multiplier,
> resulting in 16MIPS, vs the 10MIPS of the external 20MHz crystal without
> PLL.
>
> Thoughts?
>
> Lee
>
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