Skip to content

input.md

Latest commit

 

History

History
105 lines (78 loc) · 2.88 KB

input.md

File metadata and controls

105 lines (78 loc) · 2.88 KB
Raw

Input Profile

cardputer-zero-os owns the Cardputer Zero hardware input profile. This is separate from ZeroShell and from individual applications: every Wayland client running in the internal Zero session should see the same keyboard behavior.

Runtime Path

The internal keyboard path is:

tca8418c keyboard
  -> tca8418_keypad_m5stack kernel driver
  -> evdev input event
  -> libinput
  -> xkbcommon
  -> labwc
  -> Wayland client

Sym is not a printable key in this path. The tca8418 driver treats it as a hardware layer selector. Pressing Sym by itself produces only a scan event; pressing Sym with another key makes the driver emit the Sym-layer Linux keycode for that physical key.

Why The Console Keymap Is Not Enough

The original Cardputer keyboard support includes:

tca8418_keypad_m5stack_keymap.map

That file is a Linux console keymap. It is suitable for a virtual terminal loaded with loadkeys, but it is not read by Wayland, labwc, xkbcommon, ZeroShell, LoFiBox, AppStore, the greeter, or the polkit prompt.

For the DRM/KMS + labwc stack, the same mapping intent has to exist as an XKB profile. That is why this repository installs:

/usr/share/X11/xkb/rules/cardputerzero
/usr/share/X11/xkb/keycodes/cardputerzero
/usr/share/X11/xkb/symbols/cardputerzero

The XKB symbols are the Wayland equivalent of the legacy console keymap. They map the Sym-layer keycodes to printable characters such as !, @, {, }, |, and ?.

Linux event codes 195-199 overlap XKB's default fake modifier key names:

195 -> <LVL5>
196 -> <ALT>
197 -> <META>
198 -> <SUPR>
199 -> <HYPR>

The Cardputer profile inherits the standard evdev table, but within the Cardputer-only XKB rules it renames those five XKB keycodes to ordinary <I203> through <I207> names. That keeps the Sym layer printable without making +, -, /, \, or { also behave like Alt/Super/Level5 modifiers. Pi OS's system evdev file is not edited.

Session Scope

The Cardputer XKB profile is enabled only for the internal Zero labwc sessions:

XKB_DEFAULT_RULES=cardputerzero
XKB_DEFAULT_MODEL=pc105
XKB_DEFAULT_LAYOUT=cardputerzero

These variables are exported by:

/usr/local/bin/cardputer-zero-greeter-session
/usr/local/bin/cardputer-zero-labwc-session

and are also present in:

/etc/xdg/cardputer-zero-greeter-labwc/environment
/etc/xdg/cardputer-zero-labwc/environment

HDMI LightDM/labwc is intentionally not changed by this profile.

Ownership Boundary

This belongs in cardputer-zero-os because it describes how the base system interprets the physical Cardputer keyboard. It must not be implemented in:

  • ZeroShell,
  • a terminal application,
  • AppStore,
  • LoFiBox,
  • or any single user application.

Applications should receive normal Wayland text/key events. They should not know that the symbol came from the Cardputer Sym hardware layer.