Now that you get "nothing". It seems like FCMEM_OFF is doing it's job, and now it's not running on the internal oscillator.

I think your problem might be the 33pf caps on the crystal. Or a bad/wrong crystal.

The datasheet shows that it should be around 22pf for 20mhz.
With FCMEM_ON, the chip will switch over to the internal oscillator if the primary isn't working. You'll see LED's blink, but it's not the right frequency for USB to work.


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DT

Q. Why do they put braille on the number pads of drive-through bank machines?