I can't wait to see more affordable RISC-V microcontrollers on the market!
The Kendryte K210 looked very cool, especially with its SIMD-ish "machine learning coprocessor", but it felt like they had rushed the hardware to market without investing in scrutable documentation or software support, last time I checked.
The GD32V series looks fantastic, since the current crop of GD32VF103 chips appear to be API-compatible with the venerable STM32F103 workhorse. But I haven't been able to find a source of the raw chips yet, it seems like you can only get them on development boards at the moment.
And there are always softcores running on FPGAs, but those sort of highlight how many permutations of "RISC-V" exist. I hope that we don't end up with too many inscrutable compiler flags to juggle as more of these chips become available.
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.
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.
In lieu of the documentation, Kendryte has _a ton_ of code on their github, so you could use that if you're looking to work on something practical. For me, having a dual core risc-v, with _TPU_ and _DSP_ onboard for $8 in single digit quantities is absolutely nuts. I frankly didn't believe it and thought the spec sheet was fake, but I've since bought some real dev boards with this chip, and they work. Even if you don't need the TPU bits, just having dual-core risc-v is more than worth the price of admission.
I don't care about TPU, don't need DSP, but dual-core - yes, please do. Having a dedicated core for hard-real time and using the other for more complicated things is way better than single core. I've seen so many projects attempting to cover timing glitches from their single cores doing everything.
I don't understand why there aren't many multi-core offerings. It's not as if the silicon would cost a lot more, especially when it would be possible to downgrade the speed and/or size.
It certainly would be pretty awesome if there was a modification of this chip without a TPU but with an MMU instead, so it'd be capable of running a proper OS rather than FreeRTOS or bare metal.
The Kendryte K210 looked very cool, especially with its SIMD-ish "machine learning coprocessor", but it felt like they had rushed the hardware to market without investing in scrutable documentation or software support, last time I checked.
The GD32V series looks fantastic, since the current crop of GD32VF103 chips appear to be API-compatible with the venerable STM32F103 workhorse. But I haven't been able to find a source of the raw chips yet, it seems like you can only get them on development boards at the moment.
And there are always softcores running on FPGAs, but those sort of highlight how many permutations of "RISC-V" exist. I hope that we don't end up with too many inscrutable compiler flags to juggle as more of these chips become available.