Re:Interesting SPI Routing with iCE40 FPGAs
by Graziano_M on Monday November 10, 2025 @11:04AM
(#45877242)
I enjoyed playing with FPGAs and all the open-source tooling makes it so much quicker and easier.
That said, I never understood the appeal of the FOMU. It's cool that it fits in a USB port, but so little IO, there's not a lot I can think to do with it.
Has anyone heard of some cool projects that others have done with this hardware?
Re:Interesting SPI Routing with iCE40 FPGAs
by Aurornis on Monday November 10, 2025 @11:22AM
(#45877496)
The primary appeal of these minimalist devices is to get people started as cheaply as possible.
They exist at a price point where it’s an easy decision to pick one up on a whim and spend an evening installing the toolchain and building some little hello world tutorial.
Re:Interesting SPI Routing with iCE40 FPGAs
by CamperBob2 on Monday November 10, 2025 @11:09AM
(#45877296)
I suppose you could create your own crypto wallet or something, but agreed, an FPGA without I/O is not a very interesting or useful thing. You'd be better off with a conventional microcontroller, I'd think.
Fantastic little device! Relating to the post, I also happened to brick one erasing the Foboot bootloader by writing the flash beyond the limit (there was a bug regarding writing to addresses beyond max at the time, but then I was pushing the limit by abusing dfu-utils :) https://x.com/sylefeb/status/1391898565061001225 ). I tried to use the programming pads but at the time was lacking the skills and it ended in disaster (ripped pads...).
Re:Interesting SPI Routing with iCE40 FPGAs
by imtringued on Tuesday November 11, 2025 @07:52AM
(#45886733)
I was thinking about an "In-system programming" use case and thought about how to best do it and the biggest problem by far is that powering the flash chip also powers the rest of the system. What a pretty niche topic to have a Baader–Meinhof phenomenon happen to you.
I have to agree with others that the "Fomu" design appears to be highly suboptimal. They could have given you a way better edge connector on the other side.
That said, I never understood the appeal of the FOMU. It's cool that it fits in a USB port, but so little IO, there's not a lot I can think to do with it.
Has anyone heard of some cool projects that others have done with this hardware?
They exist at a price point where it’s an easy decision to pick one up on a whim and spend an evening installing the toolchain and building some little hello world tutorial.
I bought one for $25 back in 2018! What's going on here?
That obviously makes the FOMU a more reasonable starter purchase, but I'd still probably get an icebreacker for $80 (which I also have and love).
Or with a more conventional FPGA development board like Icebreaker:
https://1bitsquared.com/products/icebreaker
Fantastic little device! Relating to the post, I also happened to brick one erasing the Foboot bootloader by writing the flash beyond the limit (there was a bug regarding writing to addresses beyond max at the time, but then I was pushing the limit by abusing dfu-utils :) https://x.com/sylefeb/status/1391898565061001225 ). I tried to use the programming pads but at the time was lacking the skills and it ended in disaster (ripped pads...).
The code repo for the overall project is here: https://github.com/sylefeb/tinygpus
So difficult to get the directionality right and also enable a JTAG bus
Hate these parts for that reason
I have to agree with others that the "Fomu" design appears to be highly suboptimal. They could have given you a way better edge connector on the other side.