Noch kleiner geht’s wahrscheinlich kaum: Smallest USB-C MIDI Synth.
The last few weeks I’ve been dabbling around with the CH32V003, a 32-bit RISC-V microcontroller that’s unbelievably cheap.
One of the first things that occurred to me, when I noticed it didn’t have hardware USB but the processor is clocked at 48MHz, is that it would be awesome to write a software USB stack for it. I have wanted, for a long time, to dig deep and write a bit-banged USB library, just because it’s the best way to learn. I greatly enjoyed writing my ethernet bootloader in assembly. It’s hard to justify writing a USB stack from scratch when one already exists, however, so when I saw the CH32V003 I thought this was the perfect time to do something both educational and useful.Picture my surprise to find that CNLohr has already done it! I can’t exactly complain, that’s a fantastic achievement and makes the chip even more useful and impressive than it already was.
The very least I can do is get some USB-MIDI working on the chip. At the time of writing, the USB-MIDI demo was unfinished, so I tried it out by soldering a dev board together. It started out a little smaller, but by the end of the experimentation my board looked like this: