amber cosmos Jan 15, 2026, 4:04 PM

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The idea was to create a USB 3.0 USB Stick with a built-in E-ink display. I'd really like to get feedback on the schematic before continuing anything.

USB Interface

I am using a HD3SS6126RUAR to toggle the USB Connection between an RP2040, which handles the communication with the E-ink display. The USB Port will enumerate as USB1.1 device, so I can

Upload the Software via .uf2, and

The CLI can communicate with the RP to change the contents of the display.
After 10 seconds (when the CLI hasn't sent a start ping) the device will disconnect and re-enumerate as a USB3.0 Mass Storage Device.

MSC

The USB Mass Storage Class is implemented using a GL3224, which supports up to two SD Cards or eMMCs. As Storage I choose two MTFC32GAZAQHD, from which one can be declared DNP, together with its capacitors as well as R11. If both storages are delivered, they will appear as two seperate disks on the host OS. This is intended.

The project files are available at https://github.com/HumanBot000/InkDrive

Edits

fixed D+ on RP240
Added GND Between R13 and R15
changed VBUS Regulator to 3.3V

schematic-verification-e-ink-usb3-0-storage-v0-w96uh0254jdg1.png

schematic-verification-e-ink-usb3-0-storage-v0-yl3msk4p4jdg1.png

schematic-verification-e-ink-usb3-0-storage-v0-vvfpf8pq4jdg1.png

schematic-verification-e-ink-usb3-0-storage-v0-idvwpqft4jdg1.png

GitHub

GitHub - HumanBot000/InkDrive: OSHW USB3.0 Mass Storage with E-ink ...

OSHW USB3.0 Mass Storage with E-ink display. Contribute to HumanBot000/InkDrive development by creating an account on GitHub.

ebon moth Jan 15, 2026, 4:31 PM

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First glance looks mostly readable and well thought out! one thought without opening any datasheets:
Why the 1117 (linear regulator) into the buck converters?

amber cosmos Jan 15, 2026, 4:50 PM

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ebon moth First glance looks mostly readable and well thought out! one thought without ope...

I don't know honestly, the 1117 is just my go to for non battery based projects and I added the other converters later when I needed the voltages. Maybe I will switch it so I always convert from VBUS to the Voltage, but on a thumb drive I don't really care for energy efficiency anyways.

ebon moth Jan 15, 2026, 4:54 PM

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The 1117 is a particularly old regulator (you may have come across it in tutorials or similar), but since you already have (relatively) efficient+modern buck converters on the board, consider generating the 3.3V rail with another one of those (and powering all the buck converters direct from VBUS). You're right that it doesn't matter, but why generate heat you don't need to.

amber cosmos Jan 15, 2026, 4:55 PM

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Thank you

amber cosmos Jan 15, 2026, 7:35 PM

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USB3.0 Storage with configurable E Ink Display

amber cosmos Jan 16, 2026, 5:19 PM

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Some updated pictures of the schematics, with all mistakes I spotted fixed.

proven lantern Jan 16, 2026, 6:44 PM

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amber cosmos Some updated pictures of the schematics, with all mistakes I spotted fixed.

have you thought of using one of those quad buck regs or 3 buck 1 ldo chips (would be cool if you have some extra money)

amber cosmos Jan 16, 2026, 6:47 PM

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proven lantern have you thought of using one of those quad buck regs or 3 buck 1 ldo chips (wou...

Didn't come across them yet, but I will look into it and if it saves a lot footprint space it might be a good idea.

proven lantern Jan 16, 2026, 6:47 PM

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I remember seeing one on a design and it looked pretty cool

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amber cosmos Jan 17, 2026, 9:06 AM

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Is D1 necessary here? Because in theory I don't have external power and at most some loaded capacitors.

ebon moth Jan 17, 2026, 1:47 PM

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i'd say no, there's no other way that rail could be backpowered (right?)

amber cosmos Jan 17, 2026, 1:53 PM

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Not really, thank you

amber cosmos Feb 16, 2026, 1:23 PM

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Before I start with tracing, could maybe someone with a little bit more expirience look over it again? I don't know if thre's an online viewer, but the repository is on github.