5plit Keyboard Clone

A minimal split keyboard build.

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On a recent Swiss mechanical keyboard meetup I found out about this very nice, minimal split keyboard design. It consists of two identical 10x10cm PCBs (designed so that one of them is flipped) and Kailh chockolate switches, plus two venerable Arduino Pro Micros. I bought a set of PCBs there and here I am now, assembling it.

The original credit goes to llarbogey.

  • Programming and Layout

    deʃhipu10/31/2019 at 23:21 0 comments

    The diodes actually arrived the next day, and I soldered up everything, but I didn't have the energy to program it, so I let it sit there for a while.

    Today evening I finally decided to look into programming it. It turns out that there is actually a repository for this keyboard on github, with a ready configuration for the qmk firmware for it (there are also the Gerber files for the PCB there):

    The way you use it, you first need to get the firmware from and then copy the keyboard definition file to the "keyboards" directory. Then just run "make 5plit:default" to compile it, and "make 5plit:default:flash" to flash it — reset the pro micro when it tells you to. You have to program both pro micros, and the one that has the USB connected is the left one.

    The default layout looks something like this:

    The legend and the upper left is what you get by default, the one in upper right is what you get with Fn1, middle right with Fn2, and bottom right with Fn3. Middle left is what you get when you hold down the key instead of just tapping it, and upper center is what you get with Fn1 and Shift.

    I will need to actually modify this a bit, to add right Alt key — because that is how you do Polish accented characters on the Polish keyboard. But I think I can just do it as holding down the Alt key.

    I still need to learn this layout — I'm not normally a touch typist, more like a hybrid one, so this requires some getting used to.

  • Waiting for Diodes

    deʃhipu10/27/2019 at 20:26 0 comments

    All the components slowly arrived, and now I only have one thing missing: the diodes for de-ghosting the keys. Unfortunately, this design uses through-hole diodes, and I only have SMD ones in my drawers, because I avoid through-hole parts whenever I can. So I had to order them, and they take a long time. I guess in the worst case I could solder some wires to the SMD diodes, but I don't really feel like doing that for 36 diodes.

    While waiting for the diodes, I should probably start looking into programming the pro micros with the right firmware.

  • Up Side Down Handheld Keyboard

    deʃhipu10/04/2019 at 19:28 2 comments

    One project that I was thinking about since a while is a reversed keyboard, that goes on the back of a tablet or phone (or any other device with a screen), so that you can use it with all your fingers while holding the device. I realized, that if I just soldered the thumb keys on the other side of 5plit, I could make such a keyboard:

    Just imagine a tablet velcroed on top of this. I am still not sure I really want to do this, but I'm really curious why nobody does it. It seems such an obvious solution, that there must be some catch that I'm not seeing. Anybody wants to save me the effort and reveal it for me?

    I'm not sure I will do it, but it is very tempting.

  • The Swiss Mechanical Keyboard Enthusiasts Meetup

    deʃhipu10/04/2019 at 19:22 0 comments

    It all started on a Sunday, when I brought my #Alpen Clack and #Steno Keyboard projects to the sixth keyboard pervs meetup. I had my eyes on the low-profile Kailh switches since a while, but their official website only lets you order a bag of 800 pieces at the minimum, and I didn't have the energy to go out and organize a group buy. I even brought my KB390L keyboard that uses those switches, that is my favorite keyboard since two years, and that I use daily. But I saw very few keyboards using those switches, except for this:

    and this:

    I loved the minimalist approach to those keyboards (called 5plit), the chocolate switches they use, and the fact that they use the same PCB for both halves, just flipped over. And the PCB fits in 10x10cm, so it's cheap to manufacture.

    I met the author of this keyboard, and learned that he uses it for his everyday keyboarding needs, even though it started as just a silly experiment. Sounds really great. I asked if he could sell any spare PCBs, and he did, so now I have a pair of them. He also told me about the Aliexpress shop that Kailh has, where you can buy those and other switches in any quantity you want. Also key caps and everything else. So I made the order the same day, for 40 switches and as many transparent key caps, to bring this keyboard to life.

    Today the switches and key caps arrived. I still have the diodes, the jack sockets and cable, and one of the pro micros (I ran out) on order, so it probably won't be ready until next month (I go on vacation too).

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TheProgrammingRaccoon wrote 09/06/2021 at 16:12 point

hi there, i know this post is a little old, but really hope you can give me a hand here
i'm trying to compile the 5plit with qmk, both on linux and windows, and i'm having an error i don't have idea how to fix it
first saying

No layout defined in the keyboard.h or info.json

then "fatal error: pro_micro.h: no such file or directory"

i looked on qmk files and found pro_micro.h, tried to copy those files to the 5plit folder
but after doing that still getting more errors

  Are you sure? yes | no

Elliot Williams wrote 03/12/2021 at 09:20 point

Another data point: for me split ortho took a couple weeks to get OK, and a couple months for it to feel natural, but I'm a serious touch typist and had decades of muscle memory pulling my fingers down in funny directions.  Been using split ortho for all my real work for like 8 years now (what!?!?) but switching back and forth to regular keyboards has become pretty normal as well. I definitely think that split/ortho is the best.   

Different layouts are a different story.  I use a lightly chorded keyboard with 48 keys, mostly b/c I didn't feel like hand-wiring up so damn many switches, and I thought it was going to be a temporary stopgap. (Here I am two years later...)  Honestly, I still have to think about where I decided to put ~, and I'm not happy with the thumb/finger juggling needed to make {} and [] pairs, for instance. Which is to say, I _still_ find chording to be inconvenient.

If/when I make my next keyboard, it's going to have soooo many keys.  And a full complement of function keys, because right now I have 4 of them, with two modifiers to access the full 12, and while some things are muscle memory, if you tell me to hit F7, I have to think about which modifier adds 4 and which adds 8.  Not long, but it's a stumbling block, and it feels deluxe when I use a keyboard that has the full 12.  Heck, I could imagine wanting 16...

So yeah.  More keys.  

That said, I have the numbers set up so they're right under the fingers (1=a + modifier, 2=s + modifier, etc. and modifier on either thumb) and that's awesome.  Even with dedicated number keys, I think I'd still want to retain that.  

But I would kill for dedicated '"{}[] and F11.  More keys!

  Are you sure? yes | no

deʃhipu wrote 03/12/2021 at 12:16 point

Have you considered a separate macro pad for all the extra keys that you use sparingly? Effectively a 3-way split keyboard...

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Elliot Williams wrote 03/12/2021 at 14:23 point

That's not a bad idea!  I have two different "levels" that correspond to macros that I use for e.g. audio editing operations.  Remembering to toggle in and out of state when I need to type something is annoying.   

So I probably do need a macro pad that I could dedicate to all of the strange layers, while having it serve up "normal" function keys as a default.  That's a good call.

And that _would_ save me having to make yet another entire keyboard.  

Or, viewed the opposite way, that would rob me of the excuse to make yet another entire keyboard...

  Are you sure? yes | no

deʃhipu wrote 03/12/2021 at 14:48 point

You can also add knobs on it! Just think about the possibilities for an input device that doesn't have to be convenient for typing!

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Sam Apostel wrote 10/07/2019 at 15:02 point

I've been developing a web development microcomputer that has that style of handheld keyboard. It also has 2 screens that fold open and the keyboard is detachable and can be used as a normal keyboard, the screens stand up by themselves and you can switch between split code view, split web - code view and continuous code view. 

The biggest troubles with the keyboard are accidental presses and accessibility. different hand sizes don't fit the same keyboard... 

I'm very interested in how the keyboard connects through that aux jack!

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deʃhipu wrote 10/07/2019 at 15:38 point

That sounds like a very interesting project! Have you considered describing it in here?

The communication between the two halves is just simple I2C, nothing fancy. It's a 4-wire cable.

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Dan Maloney wrote 10/04/2019 at 15:13 point

How long does it take to get used to a split keyboard? I'd suspect touch typists would fare better than the hunt-and-peck types. I'm somewhere in between - no formal touch typing experience, but after 40 years my fingers just know where to go. That would probably make it very difficult for me.

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deʃhipu wrote 10/04/2019 at 19:09 point

I will let you know once I build it and get used to it. I'm not a touch typist myself: I type with 3 fingers of each hand. But maybe I just need to bite the bullet and learn this.

Also, there is one more possibility I'd love to explore, I will write about it in a log soon.

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deʃhipu wrote 03/11/2021 at 12:40 point

I forgot about this completely, but now I have more data. In my experience, it takes about a week to get used to a new keyboard geometry (as in split/whole or ortho/staggered), and about two weeks to get used to a new layout (as in keys moved to different places or requiring chording). Ortholinear keyboards really require a split or some kind of gap in the middle, with staggered keyboards you have one hand at an angle anyways. The smaller the keyboard and more layer switching you have to do, the easier to touch-type on it, since there is nowhere to move your hands to. But they are also less comfortable for coding, as all the symbols require multiple key presses. Gaming is a big problem, as it usually requires single-handed operation, and all the touch-typing setups are optimized for two hands.

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