ZMK Analog Input Driver

This driver groups ADC io channels into single input event for input subsystem. It provides config for thumbstick input with mid-point alignment, min-mav limitation, deadzone, sampling rate, reporting rate, multiplier, divisor, invertor, etc.

Caution

This poll mode driver has relativley high power consumption, its not recommended for wireless builds.

Installation

Only GitHub actions builds are covered here. Local builds are different for each user, therefore it's not possible to cover all cases.

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

manifest:
  remotes:
    ...
    # START #####
    - name: badjeff
      url-base: https://github.com/badjeff
    # END #######
  projects:
    ...
    # START #####
    - name: zmk-analog-input-driver
      remote: badjeff
      revision: main
    # END #######
    ...

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

#include <zephyr/dt-bindings/input/input-event-codes.h>
/* Reference: https://docs.zephyrproject.org/apidoc/latest/group__input__events.html */

&adc {
	status = "okay";
};

/ {
	anin0: analog_input_0 {
		compatible = "zmk,analog-input";
		sampling-hz = <100>;
		x-ch {
			io-channels = <&adc 2>; // <--- see ain-map.png for nRF52840
			mv-mid = <1630>;
			mv-min-max = <1600>;
			mv-deadzone = <10>;
			scale-multiplier = <1>;
			scale-divisor = <70>;
			invert;
			evt-type = <INPUT_EV_REL>;
			input-code = <INPUT_REL_X>;
		};
		y-ch {
			io-channels = <&adc 3>; // <--- see ain-map.png for nRF52840
			mv-mid = <1630>;
			mv-min-max = <1600>;
			mv-deadzone = <10>;
			scale-multiplier = <3>;
			scale-divisor = <4>;
			invert;
			evt-type = <INPUT_EV_REL>;
			input-code = <INPUT_REL_Y>;

			/* enable report mdoe for gamepad axix or knob */
			/* to only call input_report on quantquantized value is updated */
			/* NOTE: mouse input does NOT need this */
			report-on-change-only;

		};
	};
};

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

# Enable Analog Input
CONFIG_ADC=y
# Use async mode (Optional)
CONFIG_ADC_ASYNC=y

# Enable Analog Input Module
CONFIG_ANALOG_INPUT=y
# CONFIG_ANALOG_INPUT_LOG_LEVEL_DBG=y
# CONFIG_ANALOG_INPUT_REPORT_INTERVAL_MIN=22

# Enable logging for pre/post processed value
CONFIG_ANALOG_INPUT_LOG_DBG_RAW=y
CONFIG_ANALOG_INPUT_LOG_DBG_REPORT=y

# Just in case, you don't RTFM
CONFIG_INPUT=y

Troubleshooting

What if it just work 1 minute?

TL;DR: Set oversampling to zero at here in your zmk fork to use this module.

If you are running on nrf52840 board and analog reading get stuck after some moment, you need to ground all uint8_t adc_sequence::oversampling to zero in your ZMK branch in respect to oversampling setting is unsupported by given ADC hardware in a specific mode. Reference.