1dd2307b3f
Change the gpio_qdec driver to support optical encoders. Add a property to use for defining an arbitrary number of GPIOs for the sensing devices (typically infrared LEDs, but could also be the biasing for the phototransistor), and one for adding a delay between turning those on and reading the pin status. The infrared LEDs typically consume a non negligible amount of power, so there's also a new idle-poll-time-us property that enables two possible modes of operation: - if idle-poll-time-us is zero (default) the LEDs are enabled all the time and the driver enters polling mode using the GPIO interrupt as with mechanical encoders. This is usable for mains powered devices and has the lowest overhead on the CPU. - if idle-poll-time-us is non zero, then the driver polls the encoder all the time, turning on the LEDs just before reading the state and shutting them off immediately after, but when the encoder is idle it switches the polling rate to idle-poll-time-us to save power, and only polls at sample-time-us when some movement is detected. Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
86 lines
2.6 KiB
YAML
86 lines
2.6 KiB
YAML
# Copyright 2023 Google LLC
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# SPDX-License-Identifier: Apache-2.0
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description: |
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GPIO based QDEC input device
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Implement an input device generating relative axis event reports for a rotary
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encoder connected to two GPIOs. The driver is normally idling until it sees a
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transition on any of the encoder signal lines, then switches to polling mode
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and samples the two signal lines periodically to track the encoder position,
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and goes back to idling after the specified timeout.
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Example configuration:
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#include <zephyr/dt-bindings/input/input-event-codes.h>
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qdec {
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compatible = "gpio-qdec";
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gpios = <&gpio0 14 (GPIO_PULL_UP | GPIO_ACTIVE_HIGH)>,
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<&gpio0 13 (GPIO_PULL_UP | GPIO_ACTIVE_HIGH)>;
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steps-per-period = <4>;
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zephyr,axis = <INPUT_REL_WHEEL>;
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sample-time-us = <2000>;
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idle-timeout-ms = <200>;
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};
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compatible: "gpio-qdec"
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include: base.yaml
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properties:
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gpios:
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type: phandle-array
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required: true
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description: |
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GPIO for the A and B encoder signals.
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led-gpios:
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type: phandle-array
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description: |
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GPIOs for LED or other components needed for sensing the AB signals.
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led-pre-us:
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type: int
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description: |
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Time between enabling the led-gpios output pins and reading the encoder
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state on the input pins, meant to give the state detector (such a
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phototransistor) time to settle to right state. Required if led-gpios and
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idle-poll-time-us are specified, can be explicitly set to 0 for no delay.
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steps-per-period:
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type: int
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required: true
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description: |
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How many steps to count before reporting an input event.
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zephyr,axis:
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type: int
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required: true
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description: |
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The input code for the axis to report for the device, typically any of
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INPUT_REL_*.
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sample-time-us:
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type: int
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required: true
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description: |
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How often to sample the A and B signal lines when tracking the encoder
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movement.
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idle-poll-time-us:
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type: int
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description: |
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How often to sample the A and B signal while idling. If unset then the
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driver will use the GPIO interrupt to exit idle state, and any GPIO
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specified in led-gpios will be enabled all the time. If non zero, then
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the driver will poll every idle-poll-time-us microseconds while idle, and
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only activate led-gpios before sampling the encoder state.
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idle-timeout-ms:
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type: int
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required: true
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description: |
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Timeout for the last detected transition before stopping the sampling
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timer and going back to idle state.
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