The chips have arrived today, as predicted. And guess what! The footprint is wrong!

Turns out that the fact that it's called QFN48 doesn't mean that the pins will be spaced 0.4mm, like in the case of the ISSI chips I made a footprint for before (and re-used here), and not, say, 0.5mm like in the case of the SAMD51. Of course I should have checked the datasheet, but who does that?

In any case, ten minutes of Inkscape and I have a new footprint, hopefully better fitting. I also made the pads much longer, to make soldering by hand easier. Of course it's different size, so I had to re-arrange all the traces — but it's now much better centered, and the capacitors are aligned with the buttons, so I'm happy with it.

I was ordering a PCB for a different project already, with fast shipping, so I threw this into the order — hopefully I will have it next week.

In the mean time I can test firmware without the extra flash on the ItsyBitsy M4, simply ignoring the fact that it has the extra flash. And if I add a display module, I can also test the display speed. But that's not today.