Error message at boot: https://db.tt/mwkw0OYo
The error log shows this (it wouldn't let me take a screenshot of the log):
(Lots of those, it seems to give one every time it boots)101: 4 1 Factory timing cal constants invalid
The calibration menu shows the procedure as not being completed: https://db.tt/4FaLzlnm
The only thing I can think of to blame is my test waveform. The technical reference manual specifies that a square wave must be provided, negative-going, 1 kHz, 200mVpp, with a rise time no longer than 10ns.
I didn't have anything that would do that exactly, so I had to cobble together a pulse generator. This is what I fed it.
Note the different scale factors; the rest of the waveform is clean.
Now, is that "bump" about 13ns after the rising edge enough to make the calibration routine decide it can't work with the waveform? (Or is the rise time too fast?) I suspect the bump is due to a slight impedance mismatch, so I could work a bit harder on impedance-matching the pulse generator if I must, but it doesn't really look too bad to me. Is anybody here familiar with what the scope is actually doing during this routine, and why it would fail?
I don't have a screenshot of the actual procedure failure message - forgot to grab one - though if somebody really wants to see it, I can re-run the procedure. It looks like it's the same one it gives whenever the procedure fails, no additional information.