New PCBs (Prototyping and RaspberryPi Interfacing)

Expert (74)

06-07-2020, 10:53

I have a couple new designs for MSX, for those dyi, hands on people.
Just posted for sale, with free shipping within UK.

Interface for Raspberry Pi (and others micro controllers interface): https://www.ebay.co.uk/itm/274419614122
AT28C256 EEPROM pcb with dyi area: https://www.ebay.co.uk/itm/274415164121

Hope it is going to be useful for some folks.

Por ronivon

Expert (74)

06-07-2020, 10:56

I am trying to develop the software to write to the AT28C256 directly from MSX, but the software protection in the chip has proven challenging to implement - probably due to timing. Meanwhile, it can be written by those chinese eeprom programmers (I have a MiniPro programmer).

Por Wierzbowsky

Guardian (3649)

06-07-2020, 16:06

You definitely need to make the ground and power rails on the board thicker in the next revision. Also, it seems that the screw holes for the case are too small.

I think the only suitable chip for being programmed directly on MSX is 29F040 and similar. You can't program 27C series chips on MSX, you need an EEPROM programmer. Are you trying to create something similar to our Small Games Cartridge, but on a breadboard?

Por ronivon

Expert (74)

06-07-2020, 21:09

Hi Alexey.
Dob't think I am aware of the Small Games Cartridge. I simply put together some ideas and challenges, and created this pcb for 32K games. My idea was to have something that could be written easily, for those who wanted to prototype, but also useful for anyone that simply wanted to burn an EPROM and boot a game without much complication.

Regarding the software to write the eeprom, I can write using the MSX, but I have to manually remove the /wr jumper otherwise the MSX will overwrite the code during the boot sequence (search for RAM). I have not given up yet, will give it another try at the software protection asap.

Thanks for the helpful info on the power/ground rails and mouing hole. I will review that for next revision.

Por ronivon

Expert (74)

06-08-2020, 02:01

One update on this:

I created a repository for this project on github, and pushed changes with a revised schematic and the softwate to write the eeprom.

https://github.com/costarc/msxcart_flash32k

I also have the some pcb rev. 0 available if anyone interested.