Smallest USB Device… So Far

January 20, 2025 by Bryan Cockfield 37 Comments

For better or worse it seems to be human nature to compete with one another, as individuals or teams, rather than experience contentedness while moving to the woods and admiring nature Thoreau-style. On the plus side, competition often results in benefits for all of us, driving down costs for everything from agriculture to medical care to technology. Although perhaps a niche area of competition, the realm of “smallest USB device” seems to have a new champion: this PCB built by [Emma] that’s barely larger than the USB connector pads themselves.

With one side hosting the pads to make contact with a standard USB type-A connector, the other side’s real estate is taken up by a tiny STM32 microcontroller, four phototransistors that can arm or disarm the microcontroller, and a tiny voltage regulator that drops the 5V provided by the USB port to the 3.3V the STM32 needs to operate. This is an impressive amount of computing power for less than three millimeters of vertical space, and can operate as a HID device with a wide variety of possible use cases.

Perhaps the most obvious thing to do with a device like this would be to build a more stealthy version of this handy tool to manage micromanagers, but there are certainly other tasks that a tiny HID can be put to use towards. And, as far as the smallest USB device competition goes, we’d also note that USB-A is not the smallest connector available and, therefore, the competition still has some potential if someone can figure out how to do something similar with an even smaller USB connector.

Thanks to [JohnU] for the tip!

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Hardware-Layered Keyboard

January 20, 2025 by Kristina Panos 6 Comments

You know (or maybe you didn’t), I get super excited when y’all use the links at the bottom of this round-up we call Keebin’ to communicate with your old pal Kristina about your various labors of love. So just remember that.

Case in point: I was typing up this very issue when I heard from [Jay Crutti] and [Marcel Erz]. Both are out there making replacement keyboards for TRS-80s — [Jay] for Models 3 and 4, and [Marcel] for the Model 1. Oooh, I said to myself. This is going at the top.

A TRS-80 Model 4 with a replacement keyboard. — A TRS-80 Model 4. Image by [Jay Crutti] via JayCrutti.com

Relevant tangent time: I remember in the 90s having a pile of computers in my parents’ basement of various vintages, a TRS-80 Model 2 among them. (Did I ever tell you about the time I got pulled over for speeding with a bunch of different computers in the backseat? I was like no, officer, first of all, those are old machines that no one would really want, and I swear I didn’t steal them.)

I think the TRS-80 is probably the one I miss the most. If I still had it, you can bet I would be using [Jay] and [Marcel]’s work to build my own replacement keyboard, which the 40-year-old machine would likely need at this point if the Model 4 is any indication with its failing keyboard contacts.

To create the replacements, [Jay] used Keyboard Layout Editor (KLE), Plate & Case Builder, and EasyEDA. Using the schematic from the maintenance manual, he matched the row/column wiring of the original matrix with Cherry MX footprints. Be sure to check out [Jay]’s site for a link to the project files, or to purchase parts or an assembled keyboard. On the hunt for TRS-80 parts in general? Look no further than [Marcel]’s site.
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An Instant Gratification Game Boy Printer

January 19, 2025 by Tom Nardi 7 Comments

When the Game Boy Printer was released back in 1998, being able to produce a hard-copy of your Pokémon diploma or your latest Game Boy Camera snapshot at the touch of a button was was pretty slick indeed. But in our modern paperless society, the GB Printer somehow sticks out as even more archaic than the other add-on’s for Nintendo’s iconic handheld. Even among the folks who are still proudly playing the games that support the Printer, nobody actually wants to print anything out — although that doesn’t mean they don’t want to see the images.

The TinyGB Printer, developed by [Raphaël BOICHOT] and [Brian KHUU], could be considered something of a Game Boy Non-Printer. Powered by the RP2040 Zero development board, this open source hardware device plugs into your Game Boy and is picked up by all the games as a legitimate Printer. But instead of cranking out a little slip of thermal paper once you hit the button, the image is displayed in all its 240×240 glory on a 1.3 inch TFT display mounted to the top of the board.

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Trinteract, a small space mouse, operating in Blender.

Trinteract Mini Space Mouse Does It In 3D

January 17, 2025 by Kristina Panos 17 Comments

We’re not sure how we managed to miss this one, but better late than never, right? This is Trinteract, a 3-DOF input device that’s both open-source and Arduino compatible. There’s even a neat 3D-printed clip to add it to the side of your laptop.

Imagine navigating 2D and 3D environments, or flying around in Minecraft with ease. [Görkem]’s custom PCB features a Hall effect sensor which picks up readings from the magnet embedded in the bottom of the joystick. You can use any magnetic object as input. In the video below the break, [Görkem] shows a 3D-printed sphere with a disc magnet trapped inside as an alternative. The super-neat part is that the thing moves around entirely on flexures. You know how much we love flexures around here.

[Görkem] has written up a fantastic guide for those who must have one of their own. As a bonus, the guide details the background and thought process behind the design, which we love to see.

Don’t like magnets? This space mouse uses an accelerometer and a spring.

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Keebin’ With Kristina: The One With The Holey And Wholly Expensive Keyboard

January 13, 2025 by Kristina Panos 10 Comments

An Ultimate Hacking Keyboard (UHK) with DIY rainbow keycaps. — Image by [jwr] via reddit

The Ultimate Hacking Keyboard (UHK) line is, as the name suggests, a great choice for a lot of people. They’re each a toe-dip into the ergonomic waters with their split-ability and those beginner thumb clusters.

However, [jwr] was not completely satisfied and decided to make a custom set of keycaps. The idea was to create ‘caps without the “annoyingly abrasive texture of PBT”, that are larger than average for larger-than-average fingers. Finally, [jwr] wanted the Function row to tower over the number row a little, so these have a taller profile.

So, what are they made of? The look kind rubbery, don’t they? They are cast of pigmented polyurethane resin. First, [jwr] designed five molds in Fusion360, one for each row. Then it was time to machine master molds via CNC in foam tooling board. These were filled with silicone along with 3D-printed inserts, which produced silicone molds for casting keycaps four at a time in resin.

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Bit-Banging The USB-PD Protocol

January 10, 2025 by Bryan Cockfield 13 Comments

For one-off projects, adding a few integrated circuits to a PCB is not too big of a deal. The price of transistors is extremely low thanks to Moore and his laws, so we’re fairly free to throw chips around like peanuts. But for extremely space-constrained projects, huge production runs, or for engineering challenges, every bit of PCB real estate counts. [g3gg0] falls into the latter group, and this project aims to remove the dedicated USB-PD module from a lighting project and instead bit-bang the protocol with the ESP32 already on the board.

The modern USB power delivery (PD) protocol isn’t quite as simple as older USB ports that simply present a 5V source to whatever plugs itself into the port. But with the added complexity we get a lot more capability including different voltages and greater power handling capabilities. The first step with the PD protocol is to communicate with a power source, which requires a 1.2V 600kHz signal. Just generating the signal is challenging enough, but the data encoding for USB requires level changes to encode bits rather than voltage levels directly. With that handled, the program can then move on to encoding packets and sending them out over the bus.

After everything is said and done, [g3gg0] has a piece of software that lets the ESP32 request voltages from a power supply, sniff and log PD communication, and inject commands with vendor defined messages (VDM), all without needing to use something like a CH224K chip which would normally offload the USB-PD tasks. For anyone looking to save PCB space for whatever reason, this could be a valuable starting point. To see some more capabilities of the protocol, check out this USB-PD power supply that can deliver 2 kW.

Keebin’ With Kristina: The One With The Circuit Sculpture Keyboard

January 7, 2025 by Kristina Panos 2 Comments

The left half of GEMK-47, a mechanical keyboard with a round screen. — Image by [New-Concentrate6308] via reddit

Don’t worry, [New-Concentrate6308] is working on the GitHub for this final build of 2024, dubbed the GEMK_47. That stands for Grid Ergo Magnetic Keyboard, but I swear there are 48 keys.

What we’ve got here is a split ergo with an ortholinear layout. There’s a round screen and encoder on the left side, and a 35 mm trackpad on the right. There’s also space for some other round thing on this side, should you want another rotary encoder or whatever fits in place of the spacer.

Internally, there’s a Waveshare RP2040 Tiny and a mixture of Gateron Oil Kings and Gateron Yellow V3 switches. That lovely case is printed in silk silver PLA, but [New-Concentrate6308] wants to try metal-filled PLA for the next version. Although the original idea was to go wireless, ZMK didn’t play nicely with that round display, which of course is non-negotiable.

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