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Cheap and simple ADB to USB converter

ronan

Well-known member
Hi everyone,

I love my Alps M0116 keyboard and I have been using it daily for more than one year now.

When I was trying to find a decent ADB to USB converter I was shocked by the price. So after searching the internet I found out that the QMK firmware (that you'll know if you already built some mechanicals keyboards on you own) had support for adb keyboard !

So I bought an Arduino Pro Micro and a flashed it with this custom firmware and I was good to go. But for more than one year I was struggling because there was three wires between the pro micro and the adb connector flying and always disconnecting. So I finally got to create a small and simple PCB to clean this up and here it is :)

Here are the KiCad files : https://github.com/ronangaillard/adb2usb

You can order it on JLCPCB for instance (around 4.50$ including shipping for 5 pcbs).

The Pro Micro is worth around 10$, and you'll just need a resistor of between 1k and 10k to solder on the PCB (through hole to make things simpler for everyone).

IMG_5944.jpg

IMG_5940-1.jpg

IMG_5942.jpg


adb-usb-converter.png

For the first time you will have to flash the DFU bootloader to your Pro Micro with this doc : https://beta.docs.qmk.fm/using-qmk/guides/keyboard-building/isp_flashing_guide

You then need to install QMK :

For Mac OS :

Code:
brew install qmk/qmk/qmk

And then build firmware with :

Code:
qmk compile -kb converter/adb_usb -km default

And then flash Pro Micro with :

Code:
qmk flash -kb converter/adb_usb -km default


And you're good to go !

A really cool thing with QMK is that you can personalize your keyboard mapping very easily, for instance I remapped the "Power key" at the top of the keyboard to a Play/Pause key.

This was a really quick post about my little project, don't hesitate to ask for anything that wasn't clear !

Ronan
 

chue

Member
This is fantastic thanks for releasing it! Now I just need to get around to building a few.
 

Tom2112

Well-known member
This might be a really dumb question, so bear with me: how hard would it be to reverse this? In other words go modern USB keyboard/mouse to ADB port on Mac? I'm not so concerned about the keyboard side of things, as there are good reasons to use a genuine ADB keyboard. But the old ball mice are horrible, and a modern optical USB mouse is so much better. Having a cheap device to make that connection would be awesome. (Wombats are pricey, especially if you have multiple Macs like we all do.)
 

chue

Member
Anyone know of a part number for the adb connector? I want to make sure I buy a connector that will fit the pcb.
 

Daniël

Well-known member
Anyone know of a part number for the adb connector? I want to make sure I buy a connector that will fit the pcb.

You are looking for a Circular Mini Din, 4 contact, PCB Mount connector. Looking at various brands, it seems this is fully standardized and any brand should fit. Examples would be the TE Connectivity 5749230-1 and 5749263-1, and CUI Devices MD-40SGK, but again, any PCB mount connector should work. These were widely used for S-Video in A/V devices.
 

Skate323k137

Well-known member
Thanks for your work and docs on this!

I grabbed the git repo and generated gerbers with kicad, and ordered a small handful to try myself.

The link for the DFU bootloader is gone but I'm sure I can manage, there seems to be a little documentation elsewhere at least.
 

shadedream

Well-known member
Nice, I have one of these bare wired up on a teensy already... it was a massive pain. A little PCB like this would have made it significantly easier.

If you can find them and spend the extra for one, I recommend getting a pro micro compatible board with anything but USB micro though. Those little micro ports like to rip right off the board.
 

Skate323k137

Well-known member
Nice, I have one of these bare wired up on a teensy already... it was a massive pain. A little PCB like this would have made it significantly easier.

If you can find them and spend the extra for one, I recommend getting a pro micro compatible board with anything but USB micro though. Those little micro ports like to rip right off the board.

I'll have some extras, happy to pass along a couple if you wanted some (or if someone else in the US does).

Re the USB ports, are they cold jointed, or do they take the pads right off the PCB?
 

shadedream

Well-known member
I'll have some extras, happy to pass along a couple if you wanted some (or if someone else in the US does).

Re the USB ports, are they cold jointed, or do they take the pads right off the PCB?

Appreciate the offer, but don't need one at the moment (I mostly use my wombat currently).

I believe they tend to rip the pads right off the PCB. The USB Micro ports don't have good through-PCB support legs to hold them on. It was such an issue that the custom keyboard community designed multiple of their own USB-C pro micro clones to use instead.
 

Skate323k137

Well-known member
Ah nice, great info.

Do you use a mouse with the Wombat? My ADB keyboards are fine but it's picky with mouses and seems a bit laggy with fast movements. I haven't updated the firmware or customized any settings but it didn't like my IIgs mouse at all.
 

davewongillies

Active member
Nice, I have one of these bare wired up on a teensy already... it was a massive pain. A little PCB like this would have made it significantly easier.

If you can find them and spend the extra for one, I recommend getting a pro micro compatible board with anything but USB micro though. Those little micro ports like to rip right off the board.
For anyone looking for non-micro USB versions of the pro micro, the BIT-C fits the bill:

 

Skate323k137

Well-known member
For anyone looking for non-micro USB versions of the pro micro, the BIT-C fits the bill:

Nice, also looks like these should do for a few bucks less (b stock just means the PBC is a little thicker I guess?)
 

shadedream

Well-known member
Elite-C are the ones I've used in the past for keyboard projects. Wasn't aware of the BIT-C ones. They don't look as nice as the Elite-C for that price, but if it works it works. Looks like the BIT-C has a vendor in Europe also which may be a plus for some:

 

kitsunesoba

Well-known member
Also in the vein of Pro Micro clones (as the Elite-C is) there's also the nice!nano 2.0, which works the same way as the Pro Micro/Elite-C/etc do with the same pinout and everything (drop in replacement), but also offers connection via BLE (Bluetooth Low Energy) in addition to USB. Only difference is that you need to hook up a battery, and it would be pretty easy to find room for one of those in the case of any just about any ALPS Apple board.
 
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