Example test code fails with "Read wrong data" about psram-tang-nano-9k

[edanuff]

It is failing for me with one Nano 9K but working on another. Very strange.

EDIT: If I drop the frequency down to 51Mhz, it works on the Nano that was failing

[sorvad]

I might have another 9k knocking about. I'll see if I have and test also with that. Ahh... Just seen your edit, that's interesting. The parts may be marginal, perhaps to keep costs down the memory may be factory rejects not making exact spec but OK in most situations? Thanks for your input. I'll try reducing speed.

[svofski]

My part works well at 72MHz. Not at 81.