HID Touchpad Driver

Zephyr/ZMK driver for HID touchpads. Should work with most modern touchpads that support PTP/mouse mode.

The driver does dynamically not parse the report descriptor from the touchpad, so the reports and report structure has to be configured through device tree.

Example

ZMK example configuration for Seedstudio XIAO compatible boards, like XIAO RP2040 or Adafruit QtPy with a Framework 13 or Framework 16 touchpad.

Pinout

Touchpad	Xiao
I2C SDA	D4
I2C SCL	D5
I2C INT	D6

# west.yml
manifest:
  remotes:
    - name: FrameworkComputer
      url-base: https://github.com/FrameworkComputer
  projects:
    - name: zephyr-hid-touchpad-module
      revision: main
      remote: FrameworkComputer

# foo.conf
CONFIG_I2C=y
CONFIG_INPUT=y
CONFIG_ZMK_HID_TOUCHPAD=y
CONFIG_ZMK_MOUSE=y
CONFIG_ZMK_POINTING=y

# foo.dtsi
&xiao_i2c {
    status = "okay";

    touchpad: touchpad@2c {
        compatible = "zmk,hid-touchpad";
        status = "okay";
        reg = <0x2c>;
        dr-gpios = <&xiao_d 6 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
        // Instead of parsing the HID report descriptor in firmware
        // We configure the report IDs and report structure here
        // PCT3854 - Used on Framework 13
        mouse-report-id = <2>;
        inputmode-report-id = <6>;
        relative-x-off = <4>;
        relative-x-len = <2>;
        relative-y-off = <6>;
        relative-y-len = <2>;
        button-off = <3>;
        button-bit = <0>;
    };
};

/ {
    touchpad_input: touchpad_input {
        compatible = "zmk,input-listener";
        device = <&touchpad>;
    };
};

Support

Note, this is not an officially supported Framework product, just provided as reference for tinkerers, reusing Framework touchpad modules without the mainboard.