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cnlohr / rv003usb

CH32V003 RISC-V Pure Software USB Controller
MIT License
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Question - Could this be used as a programmer for ch32v003fun? #61

Closed Willyarma closed 4 days ago

Willyarma commented 2 months ago

I was wondering, could this USB code be adapted to be used as a programmer for ch32v003fun (for programming another device)? I know it would be a catch 22 situation, except since I've just bought 100 of these, I could make programmers for my friends. I have some ESP32S2s so not an issue for me.

cnlohr commented 2 months ago

It totally could. It's a bit tricky because both it and the USB subsystem requires very low latency control timing, but it is possible to do with DMA. It would be a fun project to get going. But it would take learning a little bit about chaining GPIO DMA off of timers. I would love to help someone seek this if they wanted.

Willyarma commented 2 months ago

Thanks for your reply. The chips haven't arrived and I have no experience with these yet. I'd have a look myself if it were simple enough, but maybe its something someone else might be interested in?

cnlohr commented 2 months ago

It will take some effort, and a logic analyzer, but it should be tractable, I have a reference implementation here - you would need to figure out how to send 1's and a 0's reliably, as well as reading bits. https://github.com/cnlohr/esp32s2-cookbook/blob/master/ch32v003programmer/main/ch32v003_swio.h#L94-L182