Added Keyboard Mapping page

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David Thurstenson 2017-06-05 16:57:36 -05:00
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Keyboard Mapping.wiki Normal file
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=Keyboard Mapping=
References:
* https://wiki.archlinux.org/index.php/Map_scancodes_to_keycodes
* https://github.com/Earnestly/pkgbuilds/blob/master/system-config/hwdb-capslock-as-control.hwdb
Maping keys is pretty simple, and if it's done at the udev level, it's universal, so it doesn't require any X or Wayland specific configuration.
As an example, I map my compose key (menu key) to right meta (aka super, logo, windows, apple, or command key), and CapsLock to left Control.
==Get Scancode==
First, get the scancode(s) of the key(s) you wish to change. Easiest way is to use `evteest(1)`. For each keypress, you'll get information similar to the following:
{{{class='prettyprint'
Event: time 1496690003.603531, -------------- SYN_REPORT ------------
Event: time 1496690003.723467, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70065
Event: time 1496690003.723467, type 1 (EV_KEY), code 127 (KEY_COMPOSE), value 0
}}}
The code you will need to use in the udev hwdb config file is the `MSC_SCAN` value (in this case: 70065).
==Get Hardware ID==
Next you will need the hardware Vendor and Product ids from `lsusb(1)`. These are two sets of four hexidecimal digits separated by a colon (:) printed right before the device name.
{{{class='prettyprint'
Bus 001 Device 005: ID 258a:1006 <keyboard name here>
}}}
In this example, the Vendor ID is `258a`, and the Product ID is `1006`.
==Create udev hwdb Configuration==
Then create `/etc/udev/hwdb.d/61-custom-keyboard.hwdb` with the following contents:
{{{class='prettyprint'
evdev:input:b0003v258Ap1006*
KEYBOARD_KEY_70065=rightmeta
KEYBOARD_KEY_70039=leftctrl
}}}
A few notes on the format of this file:
* The format for the device identifying line for usb devices is `evdev:input:b0003v<Vendor ID>p<ProductID>*`.
* If `<Product ID>` and `<Vendor ID>` contain letters, they must be capitalized
* These scancodes can be quite device-specific, so it is wise to be specific to *at least* the vendor and product IDs
* There are methods for identifying ata keyboards as well. Check the Arch Wiki page listed in the references above for more info
* Defining a key to change is done with `KEYBOARD_KEY_<scancode>=<new keycode>`
* `<scancode>` is the code we pulled from evtest earlier
* `<new keycode>` is the keycode we want to emit when the key is pressed. Names of keycodes are listed in `/usr/include/linux/input-event-codes.h`, and should be all lowercased in your udev config.
* The filename `61-custom-keyboard.hwdb` is somewhat arbitrary, but make sure that you order your file *after* the existing `60-keyboard.hwdb`.
==Update Hardware Database Index==
After changing the config files, the hwdb needs to be rebuilt:
{{{class='prettyprint'
# systemd-hwdb update
}}}
To start using this new hwdb, either reboot or tell udev to reload:
{{{class='prettyprint'
# udevadm trigger
}}}
Note that this will only work for adding or modifying existing key mappings. Deleted key mappings are kept in the kernel until a reboot.
==Testing the New Mappings==
A simple test can be run before trying the keys directly:
{{{class='prettyprint'
# udevadm info /dev/input/by-path/*-usb-*-kbd | grep KEYBOARD_KEY
}}}

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@ -10,7 +10,7 @@ Half brain dump, half documentation practice.
* [[Automating Android App Builds]] -- Documentation of my setup for building AsteroidOS Sync from https://www.github.com/asteroidos/AsteroidOSSync * [[Automating Android App Builds]] -- Documentation of my setup for building AsteroidOS Sync from https://www.github.com/asteroidos/AsteroidOSSync
* [[Audiobook RSS Feed]] * [[Audiobook RSS Feed]]
===Dotfiles=== ===Configuration/Dotfiles===
* [[Bashrc]] * [[Bashrc]]
* Tmux * Tmux
@ -19,6 +19,7 @@ Half brain dump, half documentation practice.
* [[Xinitrc]] -- Includes `srandrd` and X screen locker configuration * [[Xinitrc]] -- Includes `srandrd` and X screen locker configuration
* [[Pkglists]] * [[Pkglists]]
* [[SSH]] * [[SSH]]
* [[Keyboard Mapping]]
===Misc.=== ===Misc.===