On 27/08/2014 15:36, Neil wrote:
> (3) Without recompiling or reflashing (to ensure that there's no=20
> different optimization going on), I just changed the 8Mhz crystal to=20
> 4Mhz so it's running at 16Mhz now (with the PLL on).  This works again...
> http://veisystems.com/stuff/2014-08-27-PIC-HS-Issue-03-16Mhz%28PLL%29-GOO=
D.gif


Some PICs must be configured differently to run from a crystal up to
4MHz (XT) than when running with higher frequency crystals (HS).
Your problem may be unrelated to that, or not.

The XT and HS configurations change the gain of the amplifier in the
oscillator circuit and can make the PIC to run erratically.


Isaac



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