Launchpad clock jitter: What should I expect?

I'm seeing more jitter than I would like in the length of a pulse (e.g. 120 us) generated by timer A in PWM mode  using ACLK from the 32 KHz xtal on a G2553 Launchpad.  An eyeball estimate is a standard deviation of 15 ns.  I've pulled the header pins that connect to the xtal and removed the zero ohm jumpers.  That improved things a lot, but I'd like better if possible. Is there anything else I should consider?

This is plugged into a solderless breadboard with a 10x scope probe connected to a short  wire plugged into the row for P1.6.  LED2 is disconnected.

Is it reasonable to think that I can improve on this with the Launchpad?  I found a Freescale application note showing jitter well under 1 ns using a 32 KHz xtal feeding the PLL to generate 48 MHz USB timing.  This leads me to think it's a noise issue with the Launchpad design or my bench area (several computers running) in close proximity), but I could  be all wet.

Thanks,
Reg



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Posted by: Reginald Beardsley <[email protected]>
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