Matthias "bitluni" Balwierz's Latest RISC-V Design Is a 160-Core "Supercluster" on a Single M.2 Card
A single M.2 card, that is, if you don't count the 10 M.2-style sub-boards sticking up hedgehog-like from its back.
German maker Matthias "bitluni" Balwierz has built an M.2 add-in board that packs an impressive 160 RISC-V microcontroller cores, creating a compact "supercluster" on a stick.
"At first glance, it might look like a heavily botched SSD [Solid State Drive]," Balwierz admits of his creation, an unassuming gumstick-format green PCB with a series of "bodge" wires on its back. "[But] it's a 160-core RISC-V supercluster. [My idea was] 10 vertical M.2 slots, each with its own modular board of MCUs [Microcontroller Units]. Each module could have a different configuration if needed. Spoiler: that turned out to be a terrible idea for many reasons."
When Balwierz says "10 vertical M.2 slots," it's natural to think he's talking about the carrier board into which the cluster node boards would be placed — but that's not the case: for this project, it's the M.2 board itself which hosts the modular cluster node boards, sticking up from its surface like spines on a hedgehog.
If you're expecting extreme performance, though, you may be disappointed: the cores in question are WCH Electronics CH32V208 microcontrollers, single-core 32-bit parts based on the free and open RISC-V instruction set architecture and running at up to 144MHz. Each sub-board includes 16 individual chips, with ten slots in the overall M.2 board providing the 160 cores total.
"The numberDespite Balwierz's previous experience in building microcontroller clusters, though, the project proved challenging — and the finished board is still not fully operational. This is something Balwierz attributes to "brownout" power issues but which may be an intrinsic issue in the PCB design, with unmatched and improperly terminated traces running parallel in close proximity and the lack of a noise-limiting ground plane.
The project is documented in the video above and on Balwierz's YouTube channel, with source code and hardware design files available on GitHub under an unspecified license. "Just don't send the design to a fab before fixing it," the maker warns.