Herbert Graf wrote:
> In table 21-1 (oscillator operating modes): FRC 8MHz internal RC
> oscillator (with an odd 7.5MHz for the 16X PLL, I thought that was just
> a typo).
>
> In section 21.2.5 (Fast RC Oscillator) it says 8MHz nominal.
>
> Table 24-5: FRC (~2MIPS)

This is probably because the oscillator frequency was changed and they
neglected to update the various mentions to it in the main part of the
manual, with only the real spec in the back getting updated.

The reason for the change is that 8MHz is just a little too fast to use with
the 16x PLL.  The max it can take is 7.5MHz.  So the oscillator became
roughly "7.5MHz", except that 7.3728MHz is the next lower "baud rate"
frequency.  For some reason I can't imagine, the high speed baud rate mode
was dropped from the dsPICs, so having a frequency that is a multiple of
standard baud rates is more important than it would otherwise be.  Note that
7.3728MHz is also the standard crystal frequency for running a dsPIC at
"maximum" speed.

> Table 24-13: Oscillator Frequency - FRC - typical: 7.3728MHz??!??!?

Yeah, plus or minus what?  Specifying an RC oscillator to 5 digits is just
irresponsible, even if it is a typical spec.


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