Comments for using RPi with SPI memory

Question

Here are my notes so far. Any comments or issues please let me know. I think I am on the right track.

bbolo1 · Accepted Answer

Yes, you are correct about the HOLD pull-up resistor. As for the CS state, I have to check it on my board as well. Can you try to disconnect the SO pin of the 23K256? Of course, this means the SPI communication with this chip won't work but it is worth checking if this is the cause of the strange errors you're seeing.

clem57 · Answer

Ok!

I have learned that I should use pins 24/26 as CE0/CE1 instead of pin15(GPIO 22) because this alleviates me writing extra code. I plan on using Python SPIDEV from GitHub...

Thanks for Elektor Academy - Hardware Hacking the RPi pointing this out. Excellent if you want the details

bbolo1 · Answer

If the memory would have been powered from a different power supply I would have thought it was used as a (pseudo) non volatile memory. But I see it is powered from the 3.3V rail as the rest of the RPi board. The big question is why do you need an external SRAM of 32KB when you have 256 or 512MB in the rest of the system. If it would have been an RTC chip, this would have made more sense, but 23K256 ...