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Comment by sydthrowaway | Hacker News Reader

Are there any good <$100 RISC-V dev boards out?

Good & $100, no. The volumes being produced make that impossible right now. But there are cheaper boards around. A summary can be found in the RISC-V Foundation board giveaway (https://www.cnx-software.com/2021/05/03/the-risc-v-foundatio...), but there exist more than that. Unfortunately the one we were hoping would come out about now - the BeagleV - just got cancelled.

It would be really cool if the Raspberry Pi Foundation could jump in.

What could they do though? Raspberry Pi only exists because there are hundreds of millions of Arm CPUs being built for phones and tablets, and a tiny fraction of these end up in SBCs. The sheer volume means each chip can be had for a few dollars. There is no such ecosystem for RISC-V yet. The largest known order was AllWinner/T-Head (reportedly 5 million through TSMC).

Build hundreds of millions of of RISC-V boards?

Hundreds of millions? 180 billion.

Ah damn. Would you say synthesising a RISC-V CPU on a FPGA dev board would qualify as an alternative?

FPGA dev boards aren't that cheap, particularly one that can synthesize a 64 bit multi-core RISC-V CPU (in fact, there is one that can do it and it costs nearly $3000). The other problem with synthesized CPUs is that the clock speeds are very slow, unless you pay a great deal of money for the FPGA.

They're a lot of fun though - I have PicoRV32 in a very low end Lattice FPGA which cost, like $30 I think? It can only run single C programs, not even an embedded kernel, but I love playing around with it.

Get a large fabric Xilinx FPGA from ebay, reball it and make a simple PCB with Altium auto routing with JTAG, SPI flash, some memory. And find a license for Vivado.

You may not need a new PCB, there are systems with a big FPGA [1] that could make a good host for a RISC-V design.

[1] https://news.ycombinator.com/item?id=21303446

That’s a Spartan 6 but you really want the larger fabric parts. If you go to Digikey they will quote starting at 20k, but on ebay a few hundred will do assuming you have a Vivado license capable of building a bitstream. It is possible to commandeer a board as in that post but often not worth the time vs just making your own. Rarely prototypes with only the power distribution and JTAG appear. Those are a bit easier. Like this https://www.ebay.com/itm/114784061306?hash=item1ab9a9c77a:g:...

That board looks like it might have been a prototype of a Fusion-io card. Compare:

https://commons.wikimedia.org/wiki/File:SanDisk_Fusion_ioMem...

It's basically useless for SoC development, though, as there's no memory on board, no I/Os other than PCIe, and no practical way to add any.

The GPIO is broken out all over the PCB for the NAND. It doesn’t get easier than that

[Edit: Crowd Supply,$25... Oops!] Pine64 has very nice $4 boards, equivalent to typical ESP microcontrollers. While not up to Linux, they are wholly adequate for several totally usable embedded RTOSes.

There are actual RISC-V-based ESPs for the typical price of $3-4.

https://www.espressif.com/en/products/socs/esp32-c3

It has been my impression that ESP SOCs are really just hard-configured FPGAs. Is this correct? (There doesn't seem to be anything wrong with that, except for possible clocking / reduced power state oddities as reported in the older ESP products. I would love to learn more details about that!)

No, I specifically meant development boards, not chips. They are not much more than a chip, though (a simple antenna, 32-48 pins, a crystal oscillator, a couple of LEDs, and a couple of buttons).

https://www.aliexpress.com/item/1005002783695684.html

I misremembered both supplier AND price! It was Pine64, and only US$4.

https://pine64.com/product/pinecone-bl602-evaluation-board/

The Ali Express boards look equally intriguing. And the price is right!

I'd go with the Pine64 board. I ordered some of these BL602 boards from aliexpress (not the ones above) a few months back and the documentation is abysmal and they seem to require a windows application to program them.

From looking around the 'net I _believe_ these will work through ESP-IDF, same as the old Xtensa-based ones. Basically just `idf.py flash` the project, and it should work. Mine are still on the way, I'm eager to try.

They're standard cell logic designs (so ASICs, but what you get from letting the tooling just create a chip from the HDL more or less) that haven't had a lot of work put into power management compared to similar chips like nrf5x. They're not hard configured FPGAs. Which makes sense, as their original target was as a SDIO WIFI chip for a much larger, power hungry system, not a standalone device.

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