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 |
|---|---|---|
|
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GPIO for the A and B encoder signals.
This property is required. |
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GPIOs for LED or other components needed for sensing the AB signals.
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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.
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How many steps to count before reporting an input event.
This property is required. |
|
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The input code for the axis to report for the device, typically any of
INPUT_REL_*.
This property is required. |
|
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How often to sample the A and B signal lines when tracking the encoder
movement.
This property is required. |
|
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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.
|
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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 |
|---|---|---|
|
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Indicates the operational status of the hardware or other
resource that the node represents. In particular:
- "okay" means the resource is operational and, for example,
can be used by device drivers
- "disabled" means the resource is not operational and the system
should treat it as if it is not present
For details, see "2.3.4 status" in Devicetree Specification v0.4.
Legal values: See Important properties for more information. |
|
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This property is a list of strings that essentially define what
type of hardware or other resource this devicetree node
represents. Each device driver checks for specific compatible
property values to find the devicetree nodes that represent
resources that the driver should manage.
The recommended format is "vendor,device", The "vendor" part is
an abbreviated name of the vendor. The "device" is usually from
the datasheet.
The compatible property can have multiple values, ordered from
most- to least-specific. Having additional values is useful when the
device is a specific instance of a more general family, to allow the
system to match the most specific driver available.
For details, see "2.3.1 compatible" in Devicetree Specification v0.4.
This property is required. See Important properties for more information. |
|
|
Information used to address the device. The value is specific to
the device (i.e. is different depending on the compatible
property).
The "reg" property is typically a sequence of (address, length) pairs.
Each pair is called a "register block". Values are
conventionally written in hex.
For details, see "2.3.6 reg" in Devicetree Specification v0.4.
See Important properties for more information. |
|
|
Optional names given to each register block in the "reg" property.
For example:
/ {
soc {
#address-cells = <1>;
#size-cells = <1>;
uart@1000 {
reg = <0x1000 0x2000>, <0x3000 0x4000>;
reg-names = "foo", "bar";
};
};
};
The uart@1000 node has two register blocks:
- one with base address 0x1000, size 0x2000, and name "foo"
- another with base address 0x3000, size 0x4000, and name "bar"
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Information about interrupts generated by the device, encoded as an array
of one or more interrupt specifiers. The format of the data in this property
varies by where the device appears in the interrupt tree. Devices with the same
"interrupt-parent" will use the same format in their interrupts properties.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
See Important properties for more information. |
|
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Extended interrupt specifier for device, used as an alternative to
the "interrupts" property.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
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Optional names given to each interrupt generated by a device.
The interrupts themselves are defined in either "interrupts" or
"interrupts-extended" properties.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
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If present, this refers to the node which handles interrupts generated
by this device.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
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Human readable string describing the device. Use of this property is
deprecated except as needed on a case-by-case basis.
For details, see "4.1.2 Miscellaneous Properties" in Devicetree
Specification v0.4.
See Important properties for more information. |
|
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Information about the device's clock providers. In general, this property
should follow conventions established in the dt-schema binding:
https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml
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Optional names given to each clock provider in the "clocks" property.
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This property encodes the number of <u32> cells used by address fields
in "reg" properties in this node's children.
For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
Specification v0.4.
|
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This property encodes the number of <u32> cells used by size fields in
"reg" properties in this node's children.
For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
Specification v0.4.
|
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DMA channel specifiers relevant to the device.
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Optional names given to the DMA channel specifiers in the "dmas" property.
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IO channel specifiers relevant to the device.
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Optional names given to the IO channel specifiers in the "io-channels" property.
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Mailbox / IPM channel specifiers relevant to the device.
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Optional names given to the mbox specifiers in the "mboxes" property.
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Power domain specifiers relevant to the device.
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Optional names given to the power domain specifiers in the "power-domains" property.
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Number of cells in power-domains property
|
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Do not initialize device automatically on boot. Device should be manually
initialized using device_init().
|
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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.
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Automatically configure the device for runtime power management after the
init function runs.
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List of power states that will disable this device power.
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