First post, by Eivind
Back in 2019 I started experimenting with the Vortex86EX-based 86Duino system-on-module and made a functioning board. My focus at the time was to also build a SB-compatible add-on board, but this proved more difficult and I just got fed up with the whole project. After being inspired by rasteri's excellent weeCee project and getting my hands on a Raspberry Pi Zero 2 (more on that later), I figured I'd give this another shot...
Say hello to the TinyLlama! 😀
At a high level, the prototype board measures 100x66 mm, has an 86Duino SOM with 128MB of RAM, a Vortex86VGA board (4MB of VRAM), a Crystal CS4237B sound chip, 3.5mm audio jack, microSD, 2xUSB, micro-USB for power, RTC battery holder (CR2032). For MT32/MIDI, you can connect a Pi-Zero2 which feeds its digital audio to a GY-PCM5102 DAC, which in turn sends the analog audio back into the Crystal to be mixed. There's also pins available for a breakout board with serial and PS/2 keyboard and mouse connectors (though USB keyboards and mice work great).
Size compared to a Pi3:
One of my main goals with this project was to keep the BOM cost as low as possible. The SOM and VGA boards aren't as powerful as an ICOP Vortex86DX variant, but way less expensive. I think they're around 77 USD including mounting header pins atm. Add a cheap Pi-Zero2 and a GY-PCM5102 from AliExpress, plus the PCB, Crystal chip and standard SMD components, shouldn't be that bad.
The Vortex86EX is a strange beast, where you have to compile your own ROM with Coreboot and SeaBIOS, add various configs and the VGA ROM, and a special bunch of bytes (which DMP calls the "crossbar"), telling the Vortex how to route all of its functions to the 128 pins available. Took me quite a while to get all of that jazz working.
Status right now is that the main system is working, booting (from SD or USB) into DOS, video is fine. I'm having a bit of a rough time getting the Crystal chip working, might be a bad chip, bad soldering or something else - it's not being recognized as a PnP device. I'll post follow-ups later, might be in need of some of you CS4237-experts in here! 😉