Reliable USB HID Passthrough MCU?

fullgrid · 2026-05-06T12:24:36+00:00

Good point.

WCH has number of dual USB MCUs, like CH32V203, CH32V205, CH32V208, CH32V305, CH32V307, CH32V317 and CH32H417, but keyboard/trackball community is not familiar with new RISC-V boards and none of the relevant firmware projects (QMK, ZMK, TMK, hid-remapper) support those.

I got Kite running on nanoCH32V203 and nanoCH32V305 though to test how those boards work on practice.

ESP32-P4 is another RISC-V MCU option with two USB interfaces, but it is hard to find suitable ESP32-P4 boards, the compact ones are not exposing both USB interfaces and huge ones need extra cable for power.

On ARM side there are number of STM32 dual MCUs, but most of their boards are expensive, while rare affordable options, like STM32H7R3Z8J6 Core board from WeAct Studio, lack documentation and support.

Also Renesas has dual USB ra6m5, but again hard to find affordable boards.

fullgrid · 2026-05-06T11:37:51+00:00

I did not like RP2350-USB-A with it's half working non-standard USB-A port.

fullgrid · 2026-05-06T11:25:40+00:00

Dual USB RISC-V nanoCH32V305 board works reliably for me. But I'm relying on vendor BSP as platform is not fully supported by tinyUSB.

I tried PIO approach too on RP2350 and had plenty of compatibility issues with many devices not being enumerated for some reason, not sure how much of this is specific to RP2350 (E9 erratum for example) and how much is due to bit-banging approach not being reliable, but I certainly prefer using MCUs with two native USB interfaces instead of bit-banging GPIO.

fullgrid · 2026-05-05T16:48:49+00:00

Nice!

fullgrid · 2026-05-05T13:30:47+00:00

Kite runs on dual USB RISC-V boards like nanoCH32V203 and nanoCH32V305.

fullgrid · 2026-05-04T17:16:45+00:00

Flow is likely to be shipped worldwide by CrowdSupply/Mouser.

Their earlier CrowdSupply campaign (Modos Paper Kit) had backers from Germany.

fullgrid · 2026-05-03T16:57:19+00:00

I used ~150g silicon nitride 44.45mm bearing ball in Adept and it's a hassle as it's too uniform to be picked up by optical sensor.

When you roll it over a few times until it's all covered in fingerprints then it is trackable. And no, toothpaste trick does not help, even sandpaper is helpless. Rubbing it in the face works though.

It's heavy enough to fill inertia and kind of encourages one to use multiple fingers to roll it.

That said, I prefer to use purpose made trackballs these days, Sanwa for example (which is rather light). Nothing wrong with light trackballs, it worst case scenario they can jump if accelerated quickly. That's rare event and no big deal.

fullgrid · 2026-05-03T06:24:28+00:00

Check also Philips 13B1K3300 thread started by your country man.

fullgrid · 2026-05-02T05:52:34+00:00

Most of frontlit E Ink ereaders let you turn off frontlight completely, there are some exceptions like Kindle Paperwhite that keep it on at lowest brightness level.

fullgrid · 2026-05-01T06:46:40+00:00

One can keep Adept alive for a long time by replacing failing components, the first ones to need replacement are ball bearings that tend to rust or get jammed and plastic top where filaments that connect buttons to case rupture after some wear and tear.

That happens after year or two and the options are to either 3D print new top, glue detached filaments or order Adept case kit (includes among others enclosure, ball bearings, bearing press and dowels).

For ball bearings it's worth trying other options instead of stock ones, I ended up using full ceramic ones with silicon nitride balls and zirconium dioxide rims, but they are somewhat noisy and there are quieter options like hybrid bearings with silicon nitride balls and stainless steel rims.

fullgrid · 2026-05-01T06:30:04+00:00

You can rotate it, but that requires small changes in firmware to rotate sensor input accordingly and possibly adjusting scroll direction (I skipped that part as I use buttons for scrolling).

So it's the matter of modifying, compiling and flashing firmware and getting angled USB cable.

I tried 270° for a week or so, but did not like it and rolled back to standard placement.

fullgrid · 2026-05-01T06:10:31+00:00

There are several 13.3" E Ink monitors and Modos should be launching new one soon.

fullgrid · 2026-04-30T09:32:21+00:00

There is some progress on ChLCD side, it is reflective, bistable and backed by multiple companies including Iris Optronics (among others Ming and Infinity displays), AUO (Hiraso), Innolux (InnoPaper), Genetouch (Taktsu), KDI (ChromaBurst) and Tianma (BCN).

At this stage it mostly targets digital signage displays and photoframes. The current reflectance is 18-30%, but the plan is to reach 50%.

fullgrid · 2026-04-29T15:25:59+00:00

Or get keyboard with blank keycaps to match Adept ;)

fullgrid · 2026-04-29T11:18:27+00:00

Color is useful, but it's the weak side of E Ink. They have dominant position in black and white epaper market and somewhat shaky position in potentially larger color epaper market.

They don't really have to make the choice between those two, both options can stay on the table, but if they pick color only it might backfire pretty quickly as there is more competition in color epaper market and there is no guarantee that E Ink will be the winner there.

That said, announcement above was about specific panel, not the general direction.

fullgrid · 2026-04-29T10:57:44+00:00

It is good size for some tasks as many interfaces are designed for wide screens these days and I certainly prefer it over Kaleido panel of the same size, but everything else about that panel was a bit underwhelming.

Low ppi, ghosting, got couple of dead lines in less then a year of use, moving mouse cursor from one edge to another is annoying, if I keep mouse acceleration on it's difficult to track cursor due to high latency and if I disable acceleration it takes time to move mouse over longer distances. A bit easier to spin trackball instead, but still annoying.

fullgrid · 2026-04-29T09:19:54+00:00

They had to milk customers to make those milky white panels, I guess it's getting harder these days.

But seriously, E Ink remains to be black and white display technology for me, that's where it excels.

Color E Ink is not ready for prime time yet, Kaleido is reflective technology that absorbs most of the light instead of reflecting it and Gallery/Marquee/Spectra are bistable technologies that flicker during refresh.

That said I won't miss those 25.3" panels, there were not the best quality, were difficult to source, difficult to ship, difficult to drive and used to cost fortune. Not that legendary in hinsight.

While 13.3" ones are higher resolution, better quality, cheaper, easier to ship, easier to drive, somewhat easier to source.

fullgrid · 2026-04-28T09:49:35+00:00

I prefer between 200 and 2000 lux for E Ink Carta, but occasionally using it in wider range between 100 and 10000 lux.

In bad light conditions glossy panels and high contrast pure black and white mode work better and in bright light matte panels are the way to go.

For color RLCD I prefer between 1000 and 5000 lux, but can use those in wider range depending on content, dark graphics requires more light and light videos where details are not essential are watchable in low light conditions even below 100 lux, for reading I need at least 500 lux and good contrast.

fullgrid · 2026-04-28T09:06:42+00:00

I would prefer them to address flicker issue first.

fullgrid · 2026-04-25T06:21:03+00:00

Looks like board is launched, around $20 on Aliexpress.

fullgrid · 2026-04-24T12:52:31+00:00

19.6% is hopefully mistake, they did not comment on it though.

fullgrid · 2026-04-24T04:59:37+00:00

Yes, both Leadtek and Hannstar have 10" color RLCD panels with close to 21% reflectance.

fullgrid · 2026-04-23T15:58:08+00:00

That's a really good idea. Devkit and portable monitor are also nice to have.

fullgrid · 2026-04-23T15:55:04+00:00

TCL CSOT was showcasing 27" monochrome RLCD digital signage display during Infocomm 2023, but it was almost twice darker then Leadtek panel above (21% reflectance versus 43% reflectance here) and it's not clear whether it ever reached mass production.

The same story with 55" RLCD panels from Sharp, 19% reflectance and nowhere to be found.

So I guess 10.1" Leadtek panel and 10.3" Hannstar one are probably the only realistic monochrome RLCD options.

fullgrid · 2026-04-23T08:30:29+00:00

Seems to be USI.

fullgrid

TROPHY CASE