Kanata Keyboard Server

[gerhard-h]

A wilde idea:
Obviously kanata is not made to run as a Firmware on a keyboard.
But if kanata runs on something like a Rasberry Pi and that Rasberry identifies as a (bluetooth) keyboard to the rest of the world...

• I could connect multiple keyboards with different configurations.
• I could use kanata on any OS like Apples.
• I could run other tools like espanso on that Rasberry too.

Would that work? Or am I missing something?

[rszyma]

Seems doable.

You could run an instance of kanata with different config for each keyboard and use something like https://github.com/ruundii/bthidhub to sent the devices created by kanata over bluetooth

Differentiating devices on linux (raspberry runs linux) is not a problem. You can capture onle selected devices by using linux-dev-names-include

I haven't checked if bthidhub can bridge multiple devices at once (from the diagrams in their readme it seems like it can) or you decide to use another program that can bridge only a single device you can use another kanata instance to just combine multiple devices into one.

It looks like instead of sending the HID events via bluetooh you can also plug the raspberry pi into your computer and set USB it into HID mode https://forums.raspberrypi.com/viewtopic.php?t=341244
This could help with latency. There's probably a program on github that does exactly that.

[gerhard-h]

Besides form factor and price point I did know nothing about Rapsberry Pi. In particular I didn't consider it runs on ARM not on x86.
Found some stuff how to compile for raspberry https://medium.com/swlh/compiling-rust-for-raspberry-pi-arm-922b55dbb050 in theory.
Maybe I could use QEMU to emulate and test it, or to set up an rust dev environment on arm.
The other Direction is to use a mini pc like https://atopnuc.com/products/ubuntu-linux-mini-pc-intel-celeron-n4020-linux-computer-4gb-ram-128gb-emmc-fanless-micro-desktop-computer-suppport-hdmi-vga-2-4-5g-wifi-bt5-0-gigabit-ethernet-for-business-home or just any x86 PC with linux, und than I find solutions that expose the PC as HID device again.

[rszyma]

I tried compiling to armv7-unknown-linux-gnueabihf target and in theory it should work, but it looks like evdev crate causes a compile error:

error[E0308]: mismatched types
   --> /home/n/.cargo/registry/src/index.crates.io-6f17d22bba15001f/evdev-0.12.0/src/lib.rs:393:29
    |
393 |     let dur = Duration::new(tv.tv_sec.unsigned_abs(), tv.tv_usec as u32 * 1000);
    |               ------------- ^^^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
    |               |
    |               arguments to this function are incorrect
    |
note: associated function defined here
   --> /home/n/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/time.rs:199:18
    |
199 |     pub const fn new(secs: u64, nanos: u32) -> Duration {
    |                  ^^^
help: you can convert a `u32` to a `u64`
    |
393 |     let dur = Duration::new(tv.tv_sec.unsigned_abs().into(), tv.tv_usec as u32 * 1000);
    |                                                     +++++++

For more information about this error, try `rustc --explain E0308`.
error: could not compile `evdev` (lib) due to previous error
warning: build failed, waiting for other jobs to finish...

I guess it's an overlook from evdev devs?

[rszyma]

looks like this is fixed in evdev 0.12.1 while kanata currently uses 0.12.0
emberian/evdev#107

[jtroo]

Unfortunately this is intentional:
emberian/evdev#129

[gerhard-h]

I checked kanata's dependencies. It ist using evdev 0.13.0 meanwhile, so a "kanata server" might be possible.