Tek PS2521G NVRAM and firmware

[james_s]

I tried replacing the aging DS1220 NVRAM in my PS2521G with a F-RAM on a little adapter board I made. I found that it worked for the most part, settings would save and load as expected however I hit a showstopper in that the calibration routine fails at a couple of points. I suspect what is going on is that the calibration routine is writing multiple consecutive addresses without toggling the CS line which is used in these F-RAM chips to latch the address. I don't suppose anyone has ever explored the firmware for these PSUs? I suspect it would not be too hard to make sure CS de-asserts after each address written and asserts to write the next but I'm not sure it's worth going down that rabbit hole unless someone has already done some exploration and firmware hacking.