Mainboard Keyboard - Remix

Real long, sorry…

TLDR: CJ @ Elevated Systems is awesome, I like keyboards too. Here is my idea, hopefully it works?

The Intro
Long time fan, first time posting. I have been planning on trying to run a framework system for a year or so, but I was never sure what direction I wanted to take the project. But ProjectCJ64 from Elevated Systems showed the one true way. Heavily Inspired, with some hopefully viable extras?

I have always had a possibly tasteless and definitely expensive appreciation for everyday things unnecessarily being made out of billet aluminum… When I saw CJ’s keyboard build, one hand flew to my aging laptop, and the other hand shot towards my wallet… Early Christmas for me? :slight_smile:

Here is my concept and the stuff I have worked through so far. I think I’m 80% there? Always open to hearing feedback.

The Design - 80% concept ?

So I loved the low profile silhouette on CJ64. The Upstairs / Downstairs configuration makes a ton of sense for machining with hobbyist CNC’s, which I’m fortunate to have access to. Plus, with a clamshell design, 12 in x 8 in x 1/2 inch aluminum bar stock is a nice, readily available size of material to offer up to hungry end mills as a donation towards the final 11.7 x 5.2 x 0.9 inch finished size.

I figured there might be some room for more activities on the number row area of the keyboard. I was originally aiming for 8 multimedia keys, but the 11 mm stock height was a tight squeeze for the USB hub I used, and unfortunately, design sacrifices had to be made to the available packaging space. … for now? Hopefully the prototype will give some idea of how much more can be squeezed into that small space?

The fingerprint reader power switch and audio board are designed to fit, so I guess All Hail and Long Live the Era of available, modular components?

The Exploded View

The Unknown?
I’m a mechanical engineer professionally, but my circuit design knowledge was locked in a box along with nightmares of matrix algebra, and left at school. I’m muddling through re-learning some of it, but slowly, so please forgive me if I lack some critical understanding…

The USB C Hub seems like the easiest… I hope. My current plan is to use the USB C connector plugged into a short right angle adapter, and directly into the motherboard. Hopefully there aren’t any gremlins lurking with trying to use the power delivery feature.

Next, the Fingerprint reader needs to be fed 10 lines of FPC to its Kyocera connector. I saw that Arya from FairywrenTech has a mezzanine breakout board, and that seemed like a great low profile solution for giving the fingerprint reader what it wants. But I wanted to avoid soldering wires as part of final assembly. I was able to find the input board mezzanine connector plug and kyocera connector on either mouser or digikey, and I made a small 2-sided board similar to Arya’s but with footprint pads on top for surface mount soldering the FPR kyocera connector. My plan is to just use the FFC cable that Framework supplies with the FPR kit, and hopefully make final assembly just a ZIF connection. My rev1 versions of the boards arrived this week, and I’m currently holding my breath that

  1. I got the pin out right
  2. That my clumsy routing of the USB 2.0 data diff. pair traces and lack of a ground plane on the small 9x18 mm PCB dont conspire to wreck future Chris’s day. Stay tuned for future tears. Good or Bad is unclear…

That leaves the keyboard and the multimedia keys. Both the keyboard (Key move DK61) and the QT PY that drives the Neo key 4 key macro board use USB C as PC interfaces, but the last thing I want to do is use 2 more of the expansion bays, since that would defeat the purpose of having them there? So here I’m letting faith take the wheel and I’m switching to “I really hope this works” mode…
The 11th gen framework board, that I hope doesn’t fall victim to this plan, has a block diagram that shows that there are additional USB 2.0 data lines running through the eDP connector pins 31 & 32 (USB20_P/N8_R) and through JCAM connector Pins 20 & 21 (USB20_P/N7_R). … Maybe you see where I’m going with this?

So, I’m hoping that I’m not both very dumb and very wrong, but I think my plan is to see if I can’t just steal 5V from somewhere, connect common ground, and I want to see if I can breakout the USB 2.0 data +/- lines from the eDP and JCAM IPEX CABLINE-UM Plugs respectively to give access to 2 additional USB interfaces that should be sufficient to run the keyboard and macro pads. Again, not an expert, but if it works, I’ll be a proud dad to a bouncing baby keyboard? Fingers crossed…

As far as finding 5V goes, I think the options are:

  1. Trying to pillage from 5VALW from the FPR reader
  2. Stepping up 3v3 from the eDP or JCAM connectors
  3. Stepping down the 17v power from the eDP connector (but I suspect here lies danger)
  4. Finding 5V from some other connector on the mainboard
    Regardless of method, I’m guessing that its probably not a bad idea to put a power diode inline with wherever I steal power from to prevent back feeding?

If none of this works, and I dont lose my motherboard, I’m thinking the worst case Ontario is I lose another expansion bay in the quest for the holy USB rail.

The Project Name ??

  • work in progress. Pun based suggestions are appreciated

If you made it to the end, thanks for reading. Also, if my design aspirations are accelerating me towards certain doom, feel free to send me a message. Public design mistakes are more motivating than coffee, and I’m going to need to keep up the momentum to finish the build in the next couple weeks.

Chris - Cartesian Crafts


Heyo! Quick notes:

a) Stealing USB2 from eDP or cam connectors is likely a bother, I’d recommend using a USB hub board if you can help it. You can breakout something like the SL2.1 chip easily, or buy one of the small DIYable hubs, or just shuck any USB2 hub you have laying around for its board.

b) I think your USB2 routing will be more than fine!^^ For fingerprint reader speeds, USB is pretty robust.

c) As for 5V, if you take it off the fingerprint sensor, it’s best to limit yourself to like 300mA at most, if not less, due to the connector pin current rating. If you’re fine soldering to the board, and you seem to be, you can likely find a 5V point and grab 5V@1-2A from some FET or capacitor! No stepping up or down really necessary - the mobo has a beefy 5V reg, if not even two of them (need to check block dia sometime).

d) I have a board that adds a fingerprint sensor connector and exposes all the pins… just need to figure out the last details of it and finally start selling it :sweat_smile: