cx87-88h: a multi-layout hotswap TKL PCB

ClackX cx87-88h
A multi-layout hotswap TKL PCB



Hello everyone, I'm doctorboy from Portugal and I would like to introduce my new project, a multi-layout hotswap PCB.

I'm an ISO lover and always try to build my boards with the ISO layout. It is also very normal to me that when building a new keyboard, I don't get the configuration right on the first try. I enjoy doing 2-3 different configurations to see what I prefer the most. In my point of view, this is one of the strongest use cases for hotswap PCBs. They allow one to easily change the configuration and find the right combination between plates, switches, etc. so I can then use the solderable PCB for my final build.
However, hotswap PCBs usually only support one layout, and even on very popular TKL boards, ISO layout is not available on the hotswap version. TKL layout also offers a multitude of different variations (USB port needed, USB daughterboard needed, F13 layout, 7u spacebar, etc.), which makes having the right hotswap PCB for the board that you are buying, very challenging.

So, I decided to make something about this, and I designed a multi-layout hotswap PCB.

English is not my native language; sorry in advance if some explanation or message is unclear.
I leave below the link for the IC form, where all feedback is very much welcome.

IC Form

Without further ado, I'd like to present the project more clearly.


0. Contents

• LAYOUT SUPPORT
• GEEK AREA - SPECS
• PHOTOS
• NOTES AND PRICE
• CREDITS AND FINAL NOTES

1. Layout Support




3. Geek Area—Specs

• FR4 TKL PCB with 1.6mm - with 0.25u space between the two top rows.
• Programmable via QMK/VIA/VIAL.
• Similar footprint as Hiney TKL h87/88 PCBs.
• Support of F12 and F13 layouts.
• Support of ANSI and ISO layout.
• Support of WKL/WK 7u and standard ANSI (6.25u) bottom row.
• Support of stepped Caps Lock.
• Compatible with right-side USB port (located between F12 and PrintScreen key).
• Includes JST and Molex connectors to support Unified daughterboard C and S series (JST placement is similar to h88nu board).
• Breakaway USB port for cases that use USB daughterboards.
• North-facing spacebar stab (the stab wire is located on the north side of the switch).
• Powered by STM32 MCU.
• One physical reset button in front and another on the back, for facilitating access.
• ARM debug pins.
• No RGB (underglow or per key).
• No meme or flex cuts.
• Only one led in the scroll lock key, since by supporting the stepped Caps Lock, there is no space for the Caps Lock led.
• Black colour (likely matte black) solder mask w/ white text and a cool design on the top side.

Note that compatibility will vary for this PCB. It is not a drop-in PCB for any TKL. It will be the buyer's responsibility to ensure that the PCB will work with their target case/board. As a starting point, you can consider this PCB compatible with boards that are compatible with Hiney H87/88 north spacebar versions.


3. Photos
I apologise in advance if the quality of the photos is not the best.

Prototypes




4. Notes and Price

Multi-layout support using hotswap sockets is only possible if we play with the hotswap socket position in the PCB. This means that multiple switches need to be north-facing, and some east and west-facing as well. I'm aware that this is not a perfect scenario and some issues may arise with some keycaps plus switch combinations. However, this is a common practice nowadays in many keyboards and personally, in my limited list of keysets, I never had any issues. Nevertheless, I tried to minimize the existence of "side-facing" switches at maximum and the last tests leave me to conclude that only two "side-facing" switches will be present when using ANSI or ISO layout.

I'm currently doing some internal tests with the first round of prototypes. I've already identified some areas for improvement, and I believe now is the right moment to hear more feedback from you guys. It would be wonderful if you folks could share if, first, you would like to see this going mainstream and secondly, if you would like to see anything else supported. Please also feel free to share any concerns that you may have, so I can incorporate that feedback in the next versions.

Price

For the price, I believe it is possible to achieve the target of 55€ per PCB if a MOQ of 50 is achieved. If the order number reaches 100 units or more, maybe we can drop the price to 50€. These prices aren't 100% final and are just an estimation considering prototype costs and my quotes/maths.


6. Credits and Final Notes

• Portuguese Community — always supportive, good lads.
• Others — I would also like to thank everyone who provided feedback about this project and helped me be in this position now.

I hope you found this project interesting, and hopefully, I can help the community by making this "universal" PCB. As an ISO support, it will be great to see more people playing with ISO layout and TKL boards in general, without the need to buy multiple hotswap PCBs.
I also have other small projects keyboard related (stands, stab testers, etc.) that you can find on my online store. You can also follow this and other projects I create on ClackX Instagram .
Feel free to ask questions and suggest improvements you believe would help the project.
Thanks for having me.