The goal is to make an Arduino EEPROM programmer that can write, read and erase EEPROMs of up to 16 bit address lines. I'm using them to write 8kB EEPROMs 28C64.
The design principle is that one can control the Arduino fully via Serial text commands. That way I can develop the Arduio side without need for additional software besides the Arduino Serial Monitor. After programming Arduino (Nano), type /? to the Serial Monitor to get started. Another goal is to create a Windows app to flash ROM images from a file.
Big thanks to Ben Eater and his eeprom-programmer (https://github.com/beneater/eeprom-programmer) we are familiar from the Ben Eater 8-bit computer series (check his Youtube channel for more info: https://www.youtube.com/channel/UCS0N5baNlQWJCUrhCEo8WlA). The Arduino code is heavily influenced by him.
There's no schematics of the hardware side of it. It follows almost exactly the Ben Eater schematics available online. Only difference (Ben's using 28C16 EEPROM) is that I assume 3 74LS595 shift registers instead of 2, because that way one can achieve the 16 bit address line. 28C64 could have been programmed with only two of those ICs, but I wanted to have code ready for 32kB ROMs :) Also the extra address lines must be connected to the EEPROM to their proper pins.
Designed on a cheap Arduino Nano clone from China, so I guess almost any Arduino with serial port will work :) The programmer currently assumes 28C64 EEPROM, and a Ben-Eater-like circuit. It accepts text command via serial, so one can test (or use) it manually.
Simple client that can make the Arduino serial commands, and erase/zero, read and write data to EEPROM. Currently the serial communication is done without special flow control, and it is tested to work only with my computer setup :) If it does not work, one could adjust the baud rate, or how much ROM data is sent in one command. Data verification and per byte editing would be nice additions.
I modified the https://github.com/SukkoPera/OpenC64Cart PCB design by removing all I did not need for 8K roms. You can find a pic and gerber files.
I took one of my learning projects (C64-Multicolor-Background),
and modified it to work from a cartridge. The code (without
Basic loader) is just
copy-pasted between coldstart-warmstart and 8K padding
sections, and needed no other modifications, luckily. I converted the compiled .prg file first to .crt, and then to .bin, using Vice's cartconv tool. The .bin file goes to the EEPROM.
To use the post build to convert prg to crt and bin, one needs to define cartConvPath custom post build variable in CBM Prg Studio
which should point to Vice cartconv.exe.
I will add support for 16kB cartridges (by using 28C256 which is 32kB, but 28 series 16kB rom is apparently not available). Still, keeping the PCB simple, and not adding any configurations or excess parts - great PCBs of such kind exist already. Alas, when I tried the software with 28C256, writing or reading does not work properly. Needs inspecting, maybe 28C256 is more strict with timing? Or something totally different. A tested version of 16kB PCB is already included thou!
It would be cool to add verification after writing the data to ROM.
It would be cool to be able to edit the ROM contents after writing. Not sure how usable that would be, but cool.
Sometimes first and/or last byte is not properly written, that could be investigated. It can be worked around by zeroing and erasing the ROM first, then writing. No idea yet why. Also flow control to serial communication would be nice, and be able to write whole pages (64 bytes for these 28Cxxx ROMs) at a time.