No pictures for now, but I got the Raspberry Pi hooked up to the breadboard. I ripped out all those buttons, switches, and pull/down resistors. The latches are great now.
Using python, I've been able to read and 'write' to the EEPROM. Yay, nothing has blown up!
But it's not actually writing because the software protection on it. I have tried that unlock sequence many times, and it's not working. It *is* still reading what is on there, exactly as it should, so I'm pretty sure my pins are not switched. As in, everything is working as expected except that it's not *actually* writing, just making blinky lights, etc.
Found this:
https://www.avrfreaks.net/forum/problem ... om-arduinoVery last post says Arduino can't do it for an Atmel. I have an Atmel. I also have a Pi, which might even be slower than an Arduino(?).
I can't find a straight answer on the internet or the datasheet, so I have a question going forward: If I use the chip erase feature, would that disable the software write protection? I have 12V somewhere, but trying to make that happen will not be an easy (or safe) task for me. Again this is the Atmel 28C256 EEPROM.
Thank you all for the help and advice.
Chad