Making the USB-USB Converter

[raoulduke-esq]

I talked about this in another thread, but wanted to put it here for reference. The instructions/links in TMK/QMK GitHub are a bit dated and contained some worries about clones not working. The instructions on GH for making a Pro Micro version require a 3.3v system, so here’s how to do it with current links to bootleg clone parts that I have verified to work.

Here’s my BOM:

Bootleg Leonardo $13.88
Bootleg USB Host Shield $11.99
Project Box 2-pack $9.49 (optional)
Short USB A Male-to-Female extender I had sitting around (optional)

Here’s my instructions:
1. Order parts
2. Design layouts in QMK while waiting for Amazon to show up
3. Stack Host Shield onto Leonardo
4. Flash. Either of the two reset buttons will work, and QMK Toolbox is my go-to for flashing atmegas.
5. Make a couple notches in the project box for the Leonardo’s USB cable and for the USB extension cable. Leonardo cable goes to the computer and keyboards get plugged into the extension cable. This allows the box to get closed up.
6. Optional - Add a hole in the project box you can stick a paper clip in to hit the reset button. I make sure to add a reset button to all of my layouts so after the initial flash I don’t need the physical button anymore.

At first I wanted to go the Pro Micro route because they’re hella cheap and that’s what I use for everything else, but after I found this I changed my mind. I wasn’t too keen on introducing complexity with 3.3v since all my Pro Micros are 5v/16MHz. I didn’t want to find any under power issues with hungry boards. I also didn’t want to wait 900 years for a mini-shield to be shipped from China.

[Muirium]

Good to know this works. I may well be tempted. Thanks for the tips.

[anthonymak]

I use a pro micro and a usb mini host shield for one and heak shank the combo. I also use a reed switch as reset.

[Muirium]

Boss!

[headphone_jack]

Sorry for my idiocy, but what exactly is the point of this? Couldn't you just use a $5 adapter from Amazon if you needed to change I/O?

[raoulduke-esq]

Sorry for my idiocy, but what exactly is the point of this? Couldn't you just use a $5 adapter from Amazon if you needed to change I/O?

This makes nearly any USB keyboard work under QMK so you can customize layouts, add layers, add macros, add tap dance keys, etc.

Many production keyboards are interesting but not programmable. The G80-11800, HHKB Pro Classic, and Unicom Space Saver M are some examples from my own collection. With this adapter these boards become as programmable as any custom build.

[micmil]

Sorry for my idiocy, but what exactly is the point of this? Couldn't you just use a $5 adapter from Amazon if you needed to change I/O?

Yeah, the Teensy/Pro Micro/whatever allows you to load custom firmware. It's not just going from one USB format to another. I know I was confused as hell the first time I saw this idea. It's a terrible name. "INLINE FIRMWARE ADAPTER" or "AUTOHOTKEY ON A PLATE" may have been better choices.

[raoulduke-esq]

I use a pro micro and a usb mini host shield for one and heak shank the combo. I also use a reed switch as reset.

Cool! Have you encountered any issues from being on 3.3v?

[anthonymak]

I use a pro micro and a usb mini host shield for one and heak shank the combo. I also use a reed switch as reset.

Cool! Have you encountered any issues from being on 3.3v?

the pro micro is 5V. I need to replace the regulator to make VCC output 3.3V while the mcu still running at 16Mhz.

[Jacobalbertus1]

I use a pro micro and a usb mini host shield for one and heak shank the combo. I also use a reed switch as reset.

how did you make this, i want to make one

[Muirium]

OP's link looks like the way to do it:

https://geekhack.org/index.php?topic=80421.0

Adding a (magnetic) reed switch for reset is a nice extra touch.

[AndyJ]

This makes nearly any USB keyboard work under QMK so you can customize layouts, add layers, add macros, add tap dance keys, etc.

That, and it's something you can put in a pocket or your gear bag if you're working at a customer site. All your keyboard "stuff" would be available just by unplugging the keyboard, plugging in the USB-to-USB adapter, and plugging it back in. Particularly useful if you're using customized Dvorak or Colemak layout, or utility layers like DreymarR's "Big Bag" set, which also handles mouse movement and accent characters.

Probably twice as useful if you have to move between machines with different national keymaps. The keycaps could be anything, but the layout would be whatever you programmed into the adapter.

[I suddenly realize I really do need one of these...]

[Muirium]

it's something you can put in a pocket or your gear bag if you're working at a customer site.

"Wait! What the hell is that? Is that a key-logger?"
"Well, in a sense it is, but it's actually a programmable keyboard firmware which lets me keep my sanity while suffering your lousy layout soulless chiclet keebs."

Maybe it'd go down better inside a plastic case with a McAfee logo on the side. "Oh, cyber security, gotcha." Everyone's already conditioned to place unquestioning trust into super dodgy, Russia-infiltrated antivirus vendors.

[depletedvespene]

it's something you can put in a pocket or your gear bag if you're working at a customer site.

"Wait! What the hell is that? Is that a key-logger?"
"Well, in a sense it is, but it's actually a programmable keyboard firmware which lets me keep my sanity while suffering your lousy layout soulless chiclet keebs."

Maybe it'd go down better inside a plastic case with a McAfee logo on the side. "Oh, cyber security, gotcha." Everyone's already conditioned to place unquestioning trust into super dodgy, Russia-infiltrated antivirus vendors.

Upon reading this, I kinda wish Soarer's Converter cables were fully reprogrammable with QMK — those black cables certainly can pass off as a "simple adapter". "Oh, they're a few centimeters long to ease up connection, and specially to not block a neighboring USB port on the laptop itself. You know how infuriating that can be!".

[depletedvespene]

Orihalcoooooooooooooooooooooooooooooooooooooooooooon!

[AndyJ]

"Oh, they're a few centimeters long to ease up connection, and specially to not block a neighboring USB port on the laptop itself. You know how infuriating that can be!".

[big grin]

Still, you can just arrange some papers or something over it, or stuff it behind the monitor or desk.

Though a prominent "Kaspersky Lab" on it might still be a good idea. If you can't trust the KGB, who *can* you trust?

Hm. I wonder how many people who have bought into the "USB password manager" dongles have been bitten by machines that had the USB ports disabled by the admins, or filled with glue.