Efinix FPGA with the Sapphire SoC.

After my misadventures trying to create an MSX cartridge with the help of an embedded processor, I decided to dive headfirst into the fantastic world of SoCs.

So, of course, I have some experience with FPGA programming, but I have never attempted the experiment of implementing a processor that can be debugged in real-time.

In the past, I have implemented Z80 and even 68000 cores. But each time, it was to run code already developed for the version with a 'real' processor.

Here, the goal is to develop a new application. In fact, it's about porting the routines I already created for the STM32 processor-based MSX card to the embedded processor from Efinix. It is a RISC-V machine with very promising capabilities.

I struggled a bit to understand how the system works and to set it up. It's actually very simple, but when you've never done this kind of thing before and everything has to be figured out on your own, it takes a little time.

After a few tests done solely with the Efinix development board, I had a small extension board made with Flash, SRAM, and an isolated USB serial port. So, I'm resuming my development on this system after a few weeks' break. Naturally, even though I had taken notes during my initial tests, I encountered a few difficulties again, but nothing serious.

A quick and dirty card designed to run at low frequency anyway.

Issues with software instability; random problems with JTAG probe conflicts.
But overall, after two or three PC reboots, everything settled down and is working perfectly fine.

And, so, a little screenshot of the system in operation. I'm just using a slightly modified example program to regularly display text strings in a terminal.

Und fertig!