Callum's Keymap

A keymap for 34 keys with half-layer mods.

  ╭              ┌─────┐                                ┌─────┐              ╮
  │        ┌─────┤  e  ├─────┬─────┐        ┌─────┬─────┤  i  ├─────┐        │
  │  ┌─────┤  w  ├─────┤  r  │  t  │        │  y  │  u  ├─────┤  o  ├─────┐  │
  │  │  q  ├─────┤  d  ├─────┼─────┤        ├─────┼─────┤  k  ├─────┤  p  │  │
  │  ├─────┤  s  ├─────┤  f  │  g  │        │  h  │  j  ├─────┤  l  ├─────┤  │
base │  a  ├─────┤  c  ├─────┼─────┤        ├─────┼─────┤  ,  ├─────┤  '  │  │
  │  ├─────┤  x  ├─────┤  v  │  b  │        │  n  │  m  ├─────┤  .  ├─────┤  │
  │  │  z  ├─────┘     └──┬──┴──┬──┴──┐  ┌──┴──┬──┴──┬──┘     └─────┤  /  │  │
  │  └─────┘              │ sym │ nav │  │space│ sym │              └─────┘  │
  ╰                       └─────┴─────┘  └─────┴─────┘                       ╯

  ╭              ┌─────┐                                ┌─────┐              ╮
  │        ┌─────┤tab- ├─────┬─────┐        ┌─────┬─────┤ up  ├─────┐        │
  │  ┌─────┤close├─────┤tab+ │lock │        │     │ bsp ├─────┤ del ├─────┐  │
  │  │swap ├─────┤ cmd ├─────┼─────┤        ├─────┼─────┤down ├─────┤ tab │  │
  │  ├─────┤ alt ├─────┤shift│ esc │        │ esc │left ├─────┤right├─────┤  │
 nav │ctrl ├─────┤back ├─────┼─────┤        ├─────┼─────┤vol+ ├─────┤enter│  │
  │  ├─────┤fresh├─────┤ fwd │boot │        │     │vol- ├─────┤play ├─────┤  │
  │  │cmd-`├─────┘     └──┬──┴──┬──┴──┐  ┌──┴──┬──┴──┬──┘     └─────┤     │  │
  │  └─────┘              │     │╳╳╳╳╳│  │     │     │              └─────┘  │
  ╰                       └─────┴─────┘  └─────┴─────┘                       ╯

  ╭              ┌─────┐                                ┌─────┐              ╮
  │        ┌─────┤  3  ├─────┬─────┐        ┌─────┬─────┤  8  ├─────┐        │
  │  ┌─────┤  2  ├─────┤  4  │  5  │        │  6  │  7  ├─────┤  9  ├─────┐  │
  │  │  1  ├─────┤ cmd ├─────┼─────┤        ├─────┼─────┤ cmd ├─────┤  0  │  │
  │  ├─────┤ alt ├─────┤shift│ esc │        │ esc │shift├─────┤ alt ├─────┤  │
sym* │ctrl ├─────┤  -  ├─────┼─────┤        ├─────┼─────┤  ]  ├─────┤ctrl │  │
  │  ├─────┤  `  ├─────┤  =  │     │        │     │  [  ├─────┤  ;  ├─────┤  │
  │  │caps ├─────┘     └──┬──┴──┬──┴──┐  ┌──┴──┬──┴──┬──┘     └─────┤  \  │  │
  │  └─────┘              │╳╳╳╳╳│     │  │     │╳╳╳╳╳│              └─────┘  │
  ╰                       └─────┴─────┘  └─────┴─────┘         *half-layers  ╯

  ╭              ┌─────┐                                ┌─────┐              ╮
  │        ┌─────┤ f3  ├─────┬─────┐        ┌─────┬─────┤ f8  ├─────┐        │
  │  ┌─────┤ f2  ├─────┤ f4  │ f5  │        │ f6  │ f7  ├─────┤ f9  ├─────┐  │
  │  │ f1  ├─────┤ cmd ├─────┼─────┤        ├─────┼─────┤ cmd ├─────┤ f10 │  │
  │  ├─────┤ alt ├─────┤shift│ esc │        │ esc │shift├─────┤ alt ├─────┤  │
 fn* │ctrl ├─────┤     ├─────┼─────┤        ├─────┼─────┤     ├─────┤ctrl │  │
  │  ├─────┤ f12 ├─────┤     │     │        │     │     ├─────┤     ├─────┤  │
  │  │ f11 ├─────┘     └──┬──┴──┬──┴──┐  ┌──┴──┬──┴──┬──┘     └─────┤     │  │
  │  └─────┘              │     │╳╳╳╳╳│  │     │╳╳╳╳╳│              └─────┘  │
  ╰                       └─────┴─────┘  └─────┴─────┘      *nav + right sym ╯

Design

I love tiny keyboards but find myself frustrated by many of the popular mechanisms to handle modifiers.

• Mod-tap -- timing issues. If you roll quickly from a to b then is that supposed to be a then b or b modified by a?
• Chording -- same timing issues as mod-tap. If you roll quickly from a to b then is that supposed to be a then b or the a + b chord?
• Oneshot mods / "callum mods" (my previously proposed method) -- solve the timing issues with mod-tap and chords, but at the expense of being slower in general. It turns what could be a single fluid movement into two distinct movements. This is most egregious when making multiple keypresses while "holding" the same modifiers, requiring you to re-activate the modifiers for each keypress.

After some experimentation I think I've found a solution that relies on purely the oldest keyboard trick in the book: the humble layer (with an extremely minor twist).

Half-layer mods

The minor twist is to make use of what I'm going to call half-layers -- layers that can be activated on each half of the keyboard independently. sym above consists of two half-layers, with a key on each thumb. Holding left sym activates just the left half, and holding right sym activates just the right half. Both halves have home row modifiers, so to modify a key on the left half of base we can use right sym without obscuring the key we want to modify (e.g. cmd + c becomes right sym + right cmd + c).

  ╭              ┌─────┐                                ┌─────┐              ╮
  │        ┌─────┤  e  ├─────┬─────┐        ┌─────┬─────┤  8  ├─────┐        │
  │  ┌─────┤  w  ├─────┤  r  │  t  │        │  6  │  7  ├─────┤  9  ├─────┐  │
  │  │  q  ├─────┤  d  ├─────┼─────┤        ├─────┼─────┤╳╳╳╳╳├─────┤  0  │  │
  │  ├─────┤  s  ├─────┤  f  │  g  │        │ esc │shift├─────┤ alt ├─────┤  │
  │  │  a  ├─────┤╳╳╳╳╳├─────┼─────┤        ├─────┼─────┤  ]  ├─────┤ctrl │  │
  │  ├─────┤  x  ├─────┤  v  │  b  │        │     │  [  ├─────┤  ;  ├─────┤  │
  │  │  z  ├─────┘     └──┬──┴──┬──┴──┐  ┌──┴──┬──┴──┬──┘     └─────┤  \  │  │
  │  └─────┘              │ sym │ nav │  │     │╳╳╳╳╳│              └─────┘  │
  ╰                       └─────┴─────┘  └─────┴─────┘                       ╯

To modify a key on sym we can activate both half-layers and use the modifiers on the other half. e.g. & becomes left sym + left shift + right sym + 7.

  ╭              ┌─────┐                                ┌─────┐              ╮
  │        ┌─────┤  3  ├─────┬─────┐        ┌─────┬─────┤  8  ├─────┐        │
  │  ┌─────┤  2  ├─────┤  4  │  5  │        │  6  │╳╳╳╳╳├─────┤  9  ├─────┐  │
  │  │  1  ├─────┤ cmd ├─────┼─────┤        ├─────┼─────┤ cmd ├─────┤  0  │  │
  │  ├─────┤ alt ├─────┤╳╳╳╳╳│ esc │        │ esc │shift├─────┤ alt ├─────┤  │
  │  │ctrl ├─────┤  -  ├─────┼─────┤        ├─────┼─────┤  ]  ├─────┤ctrl │  │
  │  ├─────┤  `  ├─────┤  =  │     │        │     │  [  ├─────┤  ;  ├─────┤  │
  │  │caps ├─────┘     └──┬──┴──┬──┴──┐  ┌──┴──┬──┴──┬──┘     └─────┤  \  │  │
  │  └─────┘              │╳╳╳╳╳│     │  │     │╳╳╳╳╳│              └─────┘  │
  ╰                       └─────┴─────┘  └─────┴─────┘                       ╯

Four keypresses to type one symbol may sound like a lot, but in practice it's one fluid movement of each hand, rolling quickly from the thumb press in to the finger press:

• Left hand holds left sym and then left shift in one rolling motion.
• Immediately following, right hand holds right sym and then hits 7 in one rolling motion.

Implementation

I'm currently running this on a Ferris. You can see my keymap.c here.