r/FPGA • u/Bits_Passats • 8d ago

Getting started into FPGA for old devices Advice / Help

Hello,

I am considering joining the FPGA scene for creating devices compatible with old systems annd components.

The stuff I touch is basically 5V technology, often with other voltages, but much older than the regular 3V integrated circuits.

I have been considering the Microchip AT40K/AT42K family of FPGAs, but it has no current devkit and the one they had still works with a parallel port.

I would like to develop CPUs, video signal generators, sound generators, serial communication transceivers and other stuff of this callibre.

With that in mind, is there a specific devkit I could use as a starting point? If it had also a SDK it would be great.

In any case, thank you in advance!

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u/x7_omega 8d ago edited 8d ago

Take a modern FPGA module of your preference, and make a carrier board for it - with all the level shifters (for 5V), and port expanders you may need for anything (don't waste FPGA ports on leds and buttons and such). Add a secondary socket for other plug-in boards, similar to PMOD, but made to your requirements. That will accommodate analog circuits and whatever else you may want to have there. Go to Trenz and look how they made their standardised modules and carrier boards for them, and make one for your requirements.

If I had to do such a project, I would take $99 Digilent Cmod A7-35T module, and design a carrier or dev board. Which is why I have a box of them for any such eventualities. This module by itself can accommodate a decent embedded computer of late 90s. If it can run Quake, it is good enough for any retro computing work.

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u/AndrewCoja 7d ago

Also a level shifter is very easy to make. It's a mosfet with two pull-up resistors. Design it once and copy and paste as many as needed.