(See also: this page with more info)

For my project for the Apple ][, I was looking for an affordable EEPROM programmer. Luckily I found on the 6502.org forum the MEEPROMMER, by Mario Keller, hosted on Github.


As I don’t have an Arduino (UNO) available, but I do have multiple Arduino Pro micro boards, one original from Sparkfun and one clone I bought somewhere online….

I set myself to make some changes to the Arduino source, as some pins are not available on the Pro micro. It did work quite fine, as I didn’t get any errors when compiling and uploading to the Micro pro also worked as it should.

Then the issues became evident: I could connect to the MEEPROMMER just fine and I could write 256 bytes to the EEPROM (AT28C64B), but as soon as I wanted to write e.g. 512 bytes or 1 kbytes, the MEEPROMMER hang. Nothing I did worked, I also added some extra debugging and found it would hang when receiving the data stream at 384 bytes. Or it would hang when expecting a (new) command.

Luckily I know someone with multiple Arduino UNO boards and he could lend me one. I uploaded an unmodified Arduino sketch to the UNO, connected the UNO to the MEEPROMMER (through some jumper wires) and I can now write the full 8 kbytes of memory of my 28C64!IMG_3417.JPG

Somehow it seems that the USB CDC implementation of the Pro micro (which sports an ATmega32u4) isn’t working fine with large data streams(??)

[If someone can explain it to me, please let me know. I would really like to make the MEEPROMMER work with the Pro micro]