If you can't afford a graphics card these days, here's an alternative solution. Just order thousands of microcontrollers, design your own boards, and build your own cluster over the course of six months after dealing with a healthy dose of setbacks. At the end of it, you might even have something able to light up the equivalent of a QVGA display with a whopping resolution of 320x200 for your efforts and, as electrical engineering and software development YouTuber bitluni said of his creation, nearly the loss of your sanity. Describing his homebrewed GPU cluster as his “nemesis,” bitluni didn’t even intend to build the device, which was designed around 8,192 $0.13 CH570 RISC-V MCUs connected to custom-designed PCBs and controlled by another 256 larger cores with FPUs. The six-month saga actually began after bitluni published a video last year detailing his original homemade GPU, which led to PCB design software firm Altium reaching out about partnering for a project. “The clusters I made before were already challenging my sanity,” bitluni explained in the cluster video he published over the weekend. “I thought I was done with the topic, but the budget and these tools would allow for a cluster of a different magnitude, and the magnitude I had in mind was just insane.” Each one of the CH570 chips bitluni acquired for the project (which he had to go directly to the manufacturer to get) runs at 100 MHz with 12 KB of SRAM, and his six-layer PCB design incorporates 32 rows of 32 chips - at least at first. When he tried to order his “blades” from his PCB manufacturer, the company’s website simply couldn’t process the request because they were so ridiculously complicated. That meant having to split each blade into two pieces, and it also meant that the full design hasn’t been realized yet - according to the video, the next version (which bitluni said he already has the parts for) will have a whopping 32,000 MCUs on it instead of the measly 8,192 version one boasts. Before he got to the completion point, there was troubleshooting to handle, though. When he received the first test blade, several of the MCUs wouldn’t work, or would only function intermittently, requiring a complete redesign, relocating traces in order to avoid interference - and several weeks of waiting to get the replacements. When the replacement test boards arrived, he had another problem: level 0 wouldn’t communicate with level 1 because he crossed his MOSI and MISO lines in the design, sending input into the output channel, and vice versa. “No matter how hard you try, you will get rx and tx wrong on the first try,” bitluni said in the video. He bypassed the error on the few sample boards he received, but the rest were correctly built. At the end of the day, the whole thing worked, including all of the individually connected RGB LEDs associated with each individually programmable MCU that serves as its QVGA equivalent. As for what v1 is capable of, bitluni said he’s planning to share that in his next video on the project, which is when he’ll also release all the design files for the project for anyone insane enough to attempt this themselves. We reached out to bitluni for additional information about his DIY GPU cluster, but didn’t hear back. ®
