gpio-qdec

Vendor: Generic or vendor-independent

Note

An implementation of a driver matching this compatible is available in drivers/input/input_gpio_qdec.c.

Description

GPIO based QDEC input device

Implement an input device generating relative axis event reports for a rotary
encoder connected to two GPIOs. The driver is normally idling until it sees a
transition on any of the encoder signal lines, then switches to polling mode
and samples the two signal lines periodically to track the encoder position,
and goes back to idling after the specified timeout.

Example configuration:

#include <zephyr/dt-bindings/input/input-event-codes.h>

qdec {
        compatible = "gpio-qdec";
        gpios = <&gpio0 14 (GPIO_PULL_UP | GPIO_ACTIVE_HIGH)>,
                <&gpio0 13 (GPIO_PULL_UP | GPIO_ACTIVE_HIGH)>;
        steps-per-period = <4>;
        zephyr,axis = <INPUT_REL_WHEEL>;
        sample-time-us = <2000>;
        idle-timeout-ms = <200>;
};

Properties

Node specific properties

Properties not inherited from the base binding file.

Name

Type

Details

gpios

phandle-array

 
GPIO for the A and B encoder signals.

This property is required.

led-gpios

phandle-array

 
GPIOs for LED or other components needed for sensing the AB signals.

led-pre-us

int

 
Time between enabling the led-gpios output pins and reading the encoder
state on the input pins, meant to give the state detector (such a
phototransistor) time to settle to right state. Required if led-gpios and
idle-poll-time-us are specified, can be explicitly set to 0 for no delay.

steps-per-period

int

 
How many steps to count before reporting an input event.

This property is required.

zephyr,axis

int

 
The input code for the axis to report for the device, typically any of
INPUT_REL_*.

This property is required.

sample-time-us

int

 
How often to sample the A and B signal lines when tracking the encoder
movement.

This property is required.

idle-poll-time-us

int

 
How often to sample the A and B signal while idling. If unset then the
driver will use the GPIO interrupt to exit idle state, and any GPIO
specified in led-gpios will be enabled all the time. If non zero, then
the driver will poll every idle-poll-time-us microseconds while idle, and
only activate led-gpios before sampling the encoder state.

idle-timeout-ms

int

 
Timeout for the last detected transition before stopping the sampling
timer and going back to idle state.

This property is required.

Deprecated node specific properties

Deprecated properties not inherited from the base binding file.

(None)

Base properties

Properties inherited from the base binding file, which defines common properties that may be set on many nodes. Not all of these may apply to the “gpio-qdec” compatible.

Name

Type

Details

status

string

 
indicates the operational status of a device

Legal values: 'ok', 'okay', 'disabled', 'reserved', 'fail', 'fail-sss'

See Important properties for more information.

compatible

string-array

 
compatible strings

This property is required.

See Important properties for more information.

reg

array

 
register space

See Important properties for more information.

reg-names

string-array

 
name of each register space

interrupts

array

 
interrupts for device

See Important properties for more information.

interrupts-extended

compound

 
extended interrupt specifier for device

interrupt-names

string-array

 
name of each interrupt

interrupt-parent

phandle

 
phandle to interrupt controller node

label

string

 
Human readable string describing the device (used as device_get_binding() argument)

See Important properties for more information.

This property is deprecated.

clocks

phandle-array

 
Clock gate information

clock-names

string-array

 
name of each clock

#address-cells

int

 
number of address cells in reg property

#size-cells

int

 
number of size cells in reg property

dmas

phandle-array

 
DMA channels specifiers

dma-names

string-array

 
Provided names of DMA channel specifiers

io-channels

phandle-array

 
IO channels specifiers

io-channel-names

string-array

 
Provided names of IO channel specifiers

mboxes

phandle-array

 
mailbox / IPM channels specifiers

mbox-names

string-array

 
Provided names of mailbox / IPM channel specifiers

power-domains

phandle-array

 
Power domain specifiers

power-domain-names

string-array

 
Provided names of power domain specifiers

#power-domain-cells

int

 
Number of cells in power-domains property

zephyr,deferred-init

boolean

 
Do not initialize device automatically on boot. Device should be manually
initialized using device_init().

wakeup-source

boolean

 
Property to identify that a device can be used as wake up source.

When this property is provided a specific flag is set into the
device that tells the system that the device is capable of
wake up the system.

Wake up capable devices are disabled (interruptions will not wake up
the system) by default but they can be enabled at runtime if necessary.

zephyr,pm-device-runtime-auto

boolean

 
Automatically configure the device for runtime power management after the
init function runs.

zephyr,disabling-power-states

phandles

 
List of power states that will disable this device power.