worldsemi,ws2812-gpio
Vendor: Worldsemi Co., Limited
Note
An implementation of a driver matching this compatible is available in drivers/led_strip/ws2812_gpio.c.
Description
Worldsemi WS2812 LED strip, GPIO binding
Driver bindings for bit-banging a WS2812 or compatible LED strip.
The CPU driver uses inline assembly, and isn't available for all
boards. The timing is automatically derived from the CPU clock frequency,
or can be provided by setting the delay-txx properties in the device
tree, or can be manually provided by the Kconfig settings DELAY_Txx.
The four delays provided (calculated based on the clock frequency,
provided by a dts, or Kconfig file) determine the delays as depicted
below. The exact timings of the LED strip data line might vary on the
type of LEDs used, consult the data-sheet for the precise timings.
0 code
+-------+ +---
| | |
| T0H | T0L |
| | |
---+ +-----------------+
1 code
+---------------+ +---
| | |
| T1H | T1L |
| | |
---+ +---------+
Example dts file:
/ {
cpus {
cpu@0 {
clock-frequency = <64000000>;
};
};
rgb_led: ws2812 {
compatible = "worldsemi,ws2812-gpio";
chain-length = <1>;
color-mapping = <LED_COLOR_ID_GREEN
LED_COLOR_ID_RED
LED_COLOR_ID_BLUE>;
gpios = <&gpio0 16 0>;
};
};
Example dts file:
/ {
chosen {
zephyr,led-strip = &rgb_led;
};
rgb_led: ws2812 {
compatible = "worldsemi,ws2812-gpio";
chain-length = <1>;
color-mapping = <LED_COLOR_ID_GREEN
LED_COLOR_ID_RED
LED_COLOR_ID_BLUE>;
reset-delay = <50>;
gpios = <&gpio0 16 0>;
delay-t1h = <48>;
delay-t1l = <32>;
delay-t0h = <16>;
delay-t0l = <32>;
};
};
Properties
Node specific properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
|---|---|---|
|
|
Number of NOP assembly operations to create a delay for a 1 bit, high
voltage period (default 700 nsec)
|
|
|
Number of NOP assembly operations to create a delay for a 1 bit, low
voltage period (default 600 nsec)
|
|
|
Number of NOP assembly operations to create a delay for a 0 bit, high
voltage period (default 350 nsec)
|
|
|
Number of NOP assembly operations to create a delay for a 0 bit, low
voltage period (default 800 nsec)
|
|
|
GPIO phandle and specifier for the pin connected to the
led-strip. Exactly one pin should be given.
This property is required. |
|
|
Minimum delay to wait (in microseconds) to make sure that the strip has
latched the signal. If omitted, a default value of 8 microseconds is used.
This default is good for the WS2812 controllers. Note that despite the
WS2812 datasheet states that a 50 microseconds delay is required, it seems
6 microseconds is enough. The default is set to 8 microseconds just to be
safe.
Default value: |
|
|
The number of devices in the daisy-chain.
This property is required. |
|
|
Channel to color mapping (or pixel order).
For example a GRB channel to color mapping would be
color-mapping = <LED_COLOR_ID_GREEN
LED_COLOR_ID_RED
LED_COLOR_ID_BLUE>;
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 “worldsemi,ws2812-gpio” compatible.
Name |
Type |
Details |
|---|---|---|
|
|
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. |
|
|
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"
|
|
|
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. |
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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. |
|
|
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
|
|
|
Optional names given to each clock provider in the "clocks" property.
|
|
|
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.
|
|
|
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.
|
|
|
DMA channel specifiers relevant to the device.
|
|
|
Optional names given to the DMA channel specifiers in the "dmas" property.
|
|
|
IO channel specifiers relevant to the device.
|
|
|
Optional names given to the IO channel specifiers in the "io-channels" property.
|
|
|
Mailbox / IPM channel specifiers relevant to the device.
|
|
|
Optional names given to the mbox specifiers in the "mboxes" property.
|
|
|
Power domain specifiers relevant to the device.
|
|
|
Optional names given to the power domain specifiers in the "power-domains" property.
|
|
|
Number of cells in power-domains property
|
|
|
Do not initialize device automatically on boot. Device should be manually
initialized using device_init().
|
|
|
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.
|
|
|
Automatically configure the device for runtime power management after the
init function runs.
|
|
|
List of power states that will disable this device power.
|