Quartz crystal frequency is wrong

Hello, I’m working on a pcb using the nrf52832, and the OS (Zephyr) crashes whenever I try to use bluetooth. This is due to some error implying timing issues. I have the dev board, and measuring the crystals on there gives wildly different frequencies than on my pcb. See below:

frequency (Hz) peak (mV) low(V)
my board X1 31.3M 66 -56
my board X2 32.3K 13.6 -13.6
dev board X1 33.3M 54 -55
dev board X2 33.3K 20 -24.8

My theory is that this is caused by poor pcb design. I started with the reference design and tried to build around it. Maybe not enough vias leading to parasitic capacitance skewing the frequency too much? Please let me know if you have ideas.

C11 and C4 have unconnected pads. See pic:
image
Did you run the DRC check before manufacturing the PCB?
Edit: C10 is also unconnected.

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That’s embarrassing. I ran it for a previous version but had to transition to kicad and didn’t because there were many false positives. I didn’t think the flood fill would be different. Thanks for spotting this

Any idea why X1 would be so different, though? it does not have that issue.

I see that you cross-posted in EEVblog and somebody pointed out that you have unconnected pads which DRC would have caught. Better fix those issues before you worry about the discrepancies.

Yes, I bodged the ground connections for C11, C4, C5, C10 and C14 and it is all working now! Thanks

Some guidelines about the crystal layout include: Do not lay out the ground (GND) pattern, vias, etc under crystal unit.

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