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Fomu An FPGA board that fits inside your USB port

55 points by Bluestein 2mo ago

amelius 2mo ago
But is it fast enough to do USB 3? If so, here's a nice and simple project idea: that board with two USB connectors and connect it to the two ends of the same cable; you send a pseudorandom bitstream down one end and verify if it comes out correctly at the other end and report the bit error rate (USB cable tester)
- jedbrooke 2mo ago
  looks like it only has the physical connections for USB 2. Fun fact about usb 3, it’s really a completely separate physical standard from usb 2, just designed in such a way that a single port can have BOTH usb 2.0 and 3.0 connectors in it at the same time. In theory this would allow for devices to use the full bandwidth of 3.0 + the full bandwidth of 2.0, but as far as I know no device does that.
  - 15155 2mo ago
    > In theory this would allow for devices to use the full bandwidth of 3.0 + the full bandwidth of 2.0, but as far as I know no device does that. Not as a single device (no XHCI controllers allow this), but yes if you presented two devices to the OS (with some XHCI controllers.)
jauntywundrkind 2mo ago
Its a cool board! Second submission on it ~7 years ago got a tiny bit of traction. https://news.ycombinator.com/item?id=19488397 https://news.ycombinator.com/item?id=19488397 There's a fun/interesting lesson on some creative routing for the ice40 FPGA FPGA here. Which I re-stumbled into just last week by happenstance. https://danielmangum.com/posts/spi-routing-ice40-fpga/ https://danielmangum.com/posts/spi-routing-ice40-fpga/ One of the makers Tim @mithro Ansell is pretty great. A bit quieter on the social media these days, but https://bsky.app/profile/mith.ro https://bsky.app/profile/mith.ro
kej 2mo ago
Apparently there is a newer Qomu device that combines the FPGA and an MCU: https://www.crowdsupply.com/quicklogic/qomu https://www.crowdsupply.com/quicklogic/qomu
yonatan8070 2mo ago
What do people do with these? I'm struggling to think of any use-case where someone would need a tiny FPGA in a USB port.
- imtringued 2mo ago
  If it used the edge of the PCB to build a USB-C port you could have added a USB-C plug to your PCB and inserted this module like a compute module and used the majority of the pins for GPIO. But in this form it is kinda useless except as a hobby.
Annatar 2mo ago
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55 points by Bluestein 2mo ago

But is it fast enough to do USB 3? If so, here's a nice and simple project idea: that board with two USB connectors and connect it to the two ends of the same cable; you send a pseudorandom bitstream down one end and verify if it comes out correctly at the other end and report the bit error rate (USB cable tester)

jedbrooke 2mo ago
looks like it only has the physical connections for USB 2. Fun fact about usb 3, it’s really a completely separate physical standard from usb 2, just designed in such a way that a single port can have BOTH usb 2.0 and 3.0 connectors in it at the same time. In theory this would allow for devices to use the full bandwidth of 3.0 + the full bandwidth of 2.0, but as far as I know no device does that.
- 15155 2mo ago
  > In theory this would allow for devices to use the full bandwidth of 3.0 + the full bandwidth of 2.0, but as far as I know no device does that. Not as a single device (no XHCI controllers allow this), but yes if you presented two devices to the OS (with some XHCI controllers.)

jauntywundrkind 2mo ago

Its a cool board! Second submission on it ~7 years ago got a tiny bit of traction. https://news.ycombinator.com/item?id=19488397 https://news.ycombinator.com/item?id=19488397 There's a fun/interesting lesson on some creative routing for the ice40 FPGA FPGA here. Which I re-stumbled into just last week by happenstance. https://danielmangum.com/posts/spi-routing-ice40-fpga/ https://danielmangum.com/posts/spi-routing-ice40-fpga/ One of the makers Tim @mithro Ansell is pretty great. A bit quieter on the social media these days, but https://bsky.app/profile/mith.ro https://bsky.app/profile/mith.ro

kej 2mo ago

Apparently there is a newer Qomu device that combines the FPGA and an MCU: https://www.crowdsupply.com/quicklogic/qomu https://www.crowdsupply.com/quicklogic/qomu

yonatan8070 2mo ago

What do people do with these? I'm struggling to think of any use-case where someone would need a tiny FPGA in a USB port.

imtringued 2mo ago
If it used the edge of the PCB to build a USB-C port you could have added a USB-C plug to your PCB and inserted this module like a compute module and used the majority of the pins for GPIO. But in this form it is kinda useless except as a hobby.

Annatar 2mo ago

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