This module add a input relay to input subsystem for ZMK.
Important
UPDATE (2024-12-12): ZMK PR #2477 has been merged into main branch. This module is no longer needed. The feature details is available on ZMK Hardware Integration for pointing devices on split peripherals.
This module sideload a new set of GATT Service and Characteratics into existing split bt paired connection. The new characteristics allow to transfer input event from peripherals to central with a relay-channel id. Then, input events would re-emitted from a zmk,virtual-device on central. The events from peripherals could be handled by zmk,input-listener on central side.
In short, user can read more than one pointing device on central and peripherals sheild simultaneously.
You might also want to checkout this module that provides opposite directional proxying for output.
Include this project on your ZMK's west manifest in config/west.yml:
manifest:
remotes:
# ...
- name: badjeff
url-base: https://github.com/badjeff
projects:
# ...
# START #####
- name: zmk-split-peripheral-input-relay
remote: badjeff
revision: main
# END #######
# ...Update board.keymap:
/ {
/* assign `input-listener` to all pointing devices */
/* &pd0 on central, &pd1 on peripheral */
trackball_central_listener {
compatible = "zmk,input-listener";
device = <&pd0>;
};
trackball_peripheral_listener {
compatible = "zmk,input-listener";
device = <&pd1>;
};
}/
Update split peripheral devicetree file board_right.overlay:
/* enable &pd0 on split peripheral. typical input device for zephyr input subsystem. */
/* NOTE 1: use the same device alias (&pd0) on central and peripheral(s) is alright. */
/* NOTE 2: input event shall be intecepted by module `zmk-split-peripheral-input-relay`. */
/* this is an alias of your actual wired input device sensor in your peripheral shield. */
/* e.g. SPI optical sensor for trackball */
&pd0 {
status = "okay";
/* the rest of sensor config should be config here, e.g. gpios */
};
/ {
/* THIS make keymap binding happy only, nothing happen on peripheral side */
pd1: virtual_input {
compatible = "zmk,virtual-input";
};
/* for peripheral side, define (input-device)-to-(relay-channel) mapping */
input_relay_config_102 {
compatible = "zmk,split-peripheral-input-relay";
/* peripheral side input device, used to... */
/* - be intecepted on peripheral; */
/* - and then, be resurrected as `zmk,virtual-device` on central; */
device = <&pd0>;
/* channel id, used to be be transfered along with all input events. */
/* NOTE 1: pick any 8bit integer. (1 - 255) */
/* NOTE 2: should matching relay-channel on central overlay */
relay-channel = <102>;
};
};
Update split central devicetree file board_left.overlay:
/* enable &pd0 on central. typical input device for zephyr input subsystem. */
/* NOTE 1: use the same device alias (&pd0) on central and peripheral(s) is alright. */
/* this is an alias of your actual wired input device sensor in your central shield. */
/* e.g. SPI optical sensor for trackball */
&pd0 {
status = "okay";
/* the rest of sensor config should be config here, e.g. gpios */
};
/ {
/* define virtual input, will be resurrected for emitting input event */
/* NOTE: set `device = <&pd1>` in `zmk,input-listener` */
pd1: virtual_input {
compatible = "zmk,virtual-input";
};
/* for central side, define (relay-channel)-to-(virtual-input) mapping */
input_relay_config_102 {
compatible = "zmk,split-peripheral-input-relay";
/* channel id, used to filter incoming input event from split peripheral */
/* NOTE: should matching relay-channel on peripheral overlay */
relay-channel = <102>;
/* virtual input device on central, which used to emit input event as an agent device */
device = <&pd1>;
};
};
Enable the input config in your all <shield>_{ left | right }.config:
CONFIG_INPUT=y
/* plus, other input device drive config */