I ended up making an "app" to do hundredths of seconds for TSD rallies. Awesome project. My build is 2-4 years old (IIRC), so it has some power issues, sometimes I'll catch it waking itself up more than usual, and I can hear the wakeups in the piezo which doesn't help.

Ben's interview on The Amp Hour [0] is pretty great as well. Awesome person, amazingly the same in person as in his video persona.

[0] https://theamphour.com/480-an-interview-with-ben-krasnow-8-y...

Not completely API-compatible. They are /extremely/ similar. Giga Devices did make an ARM STM32 clone, so they probably just did a ctrl-c, ctrl-p on the peripherals. Addresses are slightly different, and things aren't quite the same. I just ran into an issue with the system timer and it's lack of documentation... But good news is that they are pin-for-pin compatible, and you can put a raw chip onto a blue-pill board and use it!

You can get raw chips from taobao. I used taobao and a reseller, superbuy to get mine. Not bad at all!

Huh, what do you search for on Taobao to find them? I tried "GD32VF103CB" a week or two ago, but I only got results for the GD32F103 ARM clones.

I guess it makes sense that the addresses aren't quite the same; iirc ST has some licensing restrictions on their SVD/header files saying that you can't use them with other vendors' chips anyways.

Thanks for the extra information!

Whoops, I meant TMall[0], its like aliexpress vs alibaba, or vice versa. Same buying process through a third party. Apologies for that.

[0]https://list.tmall.com/search_product.htm?q=gd32vf

I'm guessing you're after the bare MCU, but for others, you can get a nice relatively cheap prototyping board with the chip from Sipeed, for example:

https://www.seeedstudio.com/Sipeed-Longan-Nano-RISC-V-GD32VF...

SeeedStudio has a few others as well:

https://www.seeedstudio.com/tag/RISCV-Board.html

Just note that you need a relatively new J-Link (v10 iirc) to program RISC-V cores using J-Link, alternatively for the Sipeed Longan boards, pick up two of them and you can flash one with a provided debugging/uploading firmware.

Yes, the Longan Nano is very nice but I'm also interested in the bare chips. Seeed also sells cheap JTAG dongles that work with their RISC-V boards, which is nice.

I've been using a clone J-Link which works pretty good. I got it probably 5 years ago, so it's impressive that it works. I think I'm using a patched version of openocd with it though.

What's the appeal in using an STM32 clone? Are you building things in quantities where saving a few pennies is really worth the headache of all the subtle incompatibilities?

The appeal is that there is a lot of good example code showing how to use the communication peripherals, but the CPU core is RISC-V instead of ARM Cortex-M3.

Also they are rated for higher clock speeds and claim better power efficiency.