PMW3610 driver implementation for ZMK

This work is based on ufan's zmk pixart sensor drivers, inorichi's zmk-pmw3610-driver, and Zephyr PMW3610 driver.

What is different to inorichi's driver

• Compatible to be used on split peripheral shield.
• Replaced CONFIG_PMW3610_ORIENTATION_* with CONFIG_PMW3610_SWAP_XY and PMW3610_INVERT_*. Then now, it can use for building conventional palm-gripping mouse.
• Moved CONFIG_PMW3610_CPI to device tree node .dts/.overlay. It is now allowed to setup diffeent config for multi-sensor on single shield. In case of building typical mouse shield, we use one movment sensor on bottom, and another sensor for scrolling on top. Those settings could be distinguishable.
• Features for scroll-mode, snipe-mode, and auto-layer are no longer needed to be provided from sensor driver. Those settings is now configurable in keymap with layer-based zmk,input-listener, instead of setup static value in shield config files.
• Seperating sampling rate and reporting rate. It reports accumulated XY axes displacement between data ready interrupts. You will still feeling lag and jumpy in noisy radio hell, but the cursor traction should being lossless, and predicable in exact terms.
• Default to use power saving config. Applying shorter-than-default downshift time to PMW3610.
• Deprecated manual chip-select. Refactored to use Zephyr's spi_transceive_dt(). That allow the sensor could be attacted to a shared SPI bus, works along with others SPI peripherals, such as display module.

Installation

Include this project on ZMK's west manifest in config/west.yml:

manifest:
  remotes:
    ...
    # START #####
    - name: badjeff
      url-base: https://github.com/badjeff
    # END #######
    ...
  projects:
    ...
    # START #####
    - name: zmk-pmw3610-driver
      remote: badjeff
      revision: main
    # END #######
    ...
  self:
    path: config

Update board.overlay adding the necessary bits (update the pins for your board accordingly):

&pinctrl {
    spi0_default: spi0_default {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 8)>,
                <NRF_PSEL(SPIM_MOSI, 0, 17)>,
                <NRF_PSEL(SPIM_MISO, 0, 17)>;
        };
    };

    spi0_sleep: spi0_sleep {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 8)>,
                <NRF_PSEL(SPIM_MOSI, 0, 17)>,
                <NRF_PSEL(SPIM_MISO, 0, 17)>;
            low-power-enable;
        };
    };
};

&spi0 {
    status = "okay";
    compatible = "nordic,nrf-spim";
    pinctrl-0 = <&spi0_default>;
    pinctrl-1 = <&spi0_sleep>;
    pinctrl-names = "default", "sleep";
    cs-gpios = <&gpio0 20 GPIO_ACTIVE_LOW>;

    trackball: trackball@0 {
        status = "okay";
        compatible = "pixart,pmw3610";
        reg = <0>;
        spi-max-frequency = <2000000>;
        irq-gpios = <&gpio0 6 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
        cpi = <600>;
        evt-type = <INPUT_EV_REL>;
        x-input-code = <INPUT_REL_X>;
        y-input-code = <INPUT_REL_Y>;
    };
};

/ {
  trackball_listener {
    compatible = "zmk,input-listener";
    device = <&trackball>;
  };
};

Enable the driver config in <shield>.config file (read the Kconfig file to find out all possible options):

CONFIG_SPI=y
CONFIG_INPUT=y
CONFIG_ZMK_POINTING=y
CONFIG_PMW3610=y
# CONFIG_PMW3610_SWAP_XY=y
# CONFIG_PMW3610_INVERT_X=y
# CONFIG_PMW3610_INVERT_Y=y
# CONFIG_PMW3610_REPORT_INTERVAL_MIN=12
# CONFIG_PMW3610_LOG_LEVEL_DBG=y
# CONFIG_PMW3610_INIT_POWER_UP_EXTRA_DELAY_MS=300 // <--see Troubleshooting

Troubleshooting

If you are getting Incorrect product id 0xFF (expecting 0x3E)! on nice_nano_v2 board from the log, you'd want to apply CONFIG_PMW3610_INIT_POWER_UP_EXTRA_DELAY_MS=1000 in your shield .conf/.overlay file. Due to this driver doesn't offer module dependancy setting, that would ensure external power (to enable VCC pin on board) is ready, the CONFIG_PMW3610_INIT_POWER_UP_EXTRA_DELAY_MS would use to add extra one second delay of power up.