What hall effect keyboards are known to work through USB?

[green-squid]

Hal effect keyboards a notorious for being amazing and stubbornly refusing to work on modern PCs. But what other HE keyboards have been successfully converted to USB? I know of only three, and two are not the most optimal, and the third is prohibitively expensive and ultra rare.

The Bud Hall effect keypad. Awesome, but only a keypad

https://geekhack.org/index.php?topic=18048.0

'grekonic' Zbrojovka Brno 263.2 keyboard. Goddamn great and in europe, but only 1Key rollover, meaning typing is horrible.

workshop-f7/soviet-gerkonic-zbrojovka-b ... 17515.html

Space Cadet and friends, oh why be so expensive
photos-f62/80s-keyboard-party-t10963.html

[ag36]

Not very familiar with circuit design but I guess nothing a external power supply can't resolve?

[Sangdrax]

Main issue is nobody has reversed engineered protocols I think even for the ones that don't need extra external power. I have a similar problem with my ITW magvalves and they work fine with USB current constraints.

Of course even an xwhatsit/DMA capsense style controller for those switch types would let people bypass all that directly too.

[XMIT]

I had a whole long thread on this a while back. Check: workshop-f7/converting-my-wang-t12379.html .

The issue is that a bunch of these older keyboards don't have protocols at all. They are 1KRO (apart from modifiers) and need to be polled externally. Vanishingly few original Micro Switch Hall boards have real controllers and protocols. Those that do are often RS232 serial - again, 1KRO.

One of my long time dream projects is a retrofit kit for vintage Micro Switch boards. This would be a PCB and sensor replacement, using new sensors that fit into the well of the Micro Switch assembly. It's sort of cheating, but the new sensors may use less power, and would certainly enable NKRO.

Using the sensors that exist on the board, and the existing PCB, options are limited if the goal is to get a modern NKRO keyboard connected via PS2 or USB. It's a hardware issue. You can play games with strobing power, or maybe get lucky and have "hold" as opposed to "pulse" sensors.

[Noobmaen]

There are some RAFI ps2 hall effect boards such as this: photos-f62/rafi-b6-c-keyboard-t13636.html

[XMIT]

Oh yeah, okay, those count. I guess the OP's title was just "Hall Effect keyboards" in general.

Off the top of my head I can't think of anything modern apart from those RAFI boards and of course the Ace Pad Tech boards.

[ag36]

Just done brief reading the thread, sounds...painful to get those working as it is. Would a optical sensor fit under the stem like music keyboards? By the way maybe the stem of the RAFI might be fixable by drilling it hollow and fitting a carbon fiber or metal rod in it?

[Noobmaen]

I was really surprised by how smooth RAFI RS 76 C is, especially because the mechanical counterpart RS 76M is rather scratchy, even in NOS condition.

[orihalcon]

Dorkvader and Slom both have done some stuff converting hall effect boards as well, some even with NKRO, though I have yet to do any experimenting myself. My understanding is that most switches CAN be converted (except the "pulse" type), and apparently also not requiring external power in some (possibly all?) cases. Should be able to get 2KRO with most switches according to the post below, with the additional possibility of NKRO fairly easily with some switch types that have an "output control pin" which Slom discovered.

Check out this post:
https://geekhack.org/index.php?topic=93 ... msg2553934

[green-squid]

Hey XMIT, I wonder if it would be possible to use the same controller you use for the new Ace Pad Tech keyboards, and fit that on that PCB you were talking about. You should contact __red__ about the PCB design. I would absolutely love for that to become a reality.

[XMIT]

Please no. It's a nice idea, but, no.

The main reason I stopped working with Ace Pad Tech is because of the complete lack of visibility I had into firmware. The manufacturers refused to provide me firmware source code and were constantly changing the microcontroller choice without asking me.

If you have a bunch of Hall sensors that are of the "hold" variety (meaning they output a logical 1 when off and a logical 0 with a key pressed), you can run that as the input to a transistor (FET). Those transistors can be modeled as a switch in series with a diode. Then, you build a matrix of those, and scan them like any keyboard matrix.

The "pulse" switches can be converted if you strobe power (meaning, turn on the switch, and see if it pulses low). You can hook that into a one-shot circuit that has the same on time as your strobe frequency and feed those into transistors as before. That would get you NKRO with the "pulse" type sensors.

All of this requires substantial rework, perhaps even a new PCB.

[green-squid]

That sucks to hear

[Sangdrax]

I had a whole long thread on this a while back. Check: workshop-f7/converting-my-wang-t12379.html

Any chance of a little more info on the ITW stuff you were working on in that same thread? Seems it would be simpler for a conversion or controller swap than Hall Effect stuff but all I've seen used on modern computers are the later era low profile PS2 ones that don't need a conversion. Like Thomas' old review https://www.youtube.com/watch?v=VbFWqH_yOPI

[lonetech]

I have a bunch of ratiometric hall sensors.. I plan to build using some hugely multichannel MCU, such as perhaps the STM32F3 series. My most recent prototype switch uses 5 plastic pieces, 3 magnets, 1 sensor and no springs. All the movement is one sliding section.