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Fluctuations on clkout pin under load

Question asked by forrester.pearl on Nov 1, 2014
Latest reply on Nov 2, 2014 by Clive One
I've noticed that the output of the clkout pin is very near the frequency I would expect when a external crystal is used as the pll source, but fluctuates a little as the CPU performs gpio operations.

When I configure the internal oscillator as the PLL source, the frequency is a bit off, which I expected, but under loads it shows very large changes in frequency.

Is this expected for the clock out behavior, or is this likely to be a power issue with my layout?

Any suggestions on how to go about tracking down the cause, assuming its abnormal?