:orphan: .. raw:: html .. dtcompatible:: worldsemi,ws2812-uart .. _dtbinding_worldsemi_ws2812_uart: worldsemi,ws2812-uart (on uart bus) ################################### .. sidebar:: Overview :Name: ``worldsemi,ws2812-uart`` :Vendor: :ref:`Worldsemi Co., Limited ` :Used in: :zephyr:board-catalog:`List of boards <#compatibles=worldsemi,ws2812-uart>` using this compatible :Driver: :zephyr_file:`drivers/led_strip/ws2812_uart.c` Description *********** .. code-block:: none Worldsemi WS2812 LED strip, UART binding Driver bindings for Worldsemi WS2812 and compatible LED strips using a UART peripheral. The driver encodes each WS2812 data bit into a multi-bit "symbol" that is transmitted via a UART. The signal timing is achieved through a combination of this node's properties: - one-symbol, - zero-symbol, - bits-per-symbol, and the parent UART's configuration: - current-speed (baudrate), - data-bits, - tx-invert (to produce the required idle-low signal), - stop-bits (must be "1" if set), - parity (must be "none" if set). The driver employs a UART frame-aware packing strategy, reusing the UART's hardware start and stop bits as part of the on-wire symbol. This packing scheme imposes a configuration constraint: the total number of bits in a UART frame must be an integer multiple of `bits-per-symbol`. Since the UART must be configured with one start bit, one stop bit, and no parity, this means the total frame size, `(2 + data-bits)`, must be evenly divisible by `bits-per-symbol`. To meet the timing requirements of the WS2812 protocol, the UART controller must support high-speed operation, typically 2.4 MHz or higher. The parent UART's `current-speed` (baudrate) property should be configured as close as possible to the ideal rate, calculated as `bits-per-symbol` times the WS2812's data rate (typically 800 kHz). For example, with a `bits-per-symbol` of 3, the target baudrate is 2.4 MHz. The internal memory buffer size is determined by `bits-per-symbol`. For each bit of pixel data, the driver generates a symbol of N bits (where N is the value of `bits-per-symbol`), which are then packed into the buffer. An example of an overlay: &uart1 { status = "okay"; /* Target baudrate is 800kHz * 3 = 2.4MHz. 2.5MHz is a close value. */ current-speed = <2500000>; /* Frame constraint: (1 start + 7 data + 1 stop) = 9 bits total. */ data-bits = <7>; /* tx-invert is required to create an idle-low signal. */ tx-invert; led_strip: ws2812-strip { compatible = "worldsemi,ws2812-uart"; status = "okay"; /* Timing based on 2.5MHz baudrate (400ns per bit): * T1H for '1' bit (2 high bits) = 2 * 400ns = 800ns. * T0H for '0' bit (1 high bit) = 1 * 400ns = 400ns. */ one-symbol = <6>; /* 0b110 */ zero-symbol = <4>; /* 0b100 */ bits-per-symbol = <3>; chain-length = <8>; reset-delay = <50>; color-mapping = ; }; }; Properties ********** .. tabs:: .. group-tab:: Node specific properties Properties not inherited from the base binding file. .. list-table:: :widths: 1 1 4 :header-rows: 1 * - Name - Type - Details * - ``one-symbol`` - ``int`` - .. code-block:: none The bit pattern that represents a single WS2812 '1' bit. The length of the pattern is defined by 'bits-per-symbol'. The pattern's MSB must be 1 (to align with the UART start bit) and its LSB must be 0 (to align with the UART stop bit). This property is **required**. * - ``zero-symbol`` - ``int`` - .. code-block:: none The bit pattern that represents a single WS2812 '0' bit. The length of the pattern is defined by 'bits-per-symbol'. The pattern's MSB must be 1 (to align with the UART start bit) and its LSB must be 0 (to align with the UART stop bit). This property is **required**. * - ``bits-per-symbol`` - ``int`` - .. code-block:: none The number of UART bits used to represent a single WS2812 data bit. The value must be between 3 and 10, inclusive. This property is **required**. * - ``reset-delay`` - ``int`` - .. code-block:: none 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: ``8`` * - ``chain-length`` - ``int`` - .. code-block:: none The number of devices in the daisy-chain. This property is **required**. * - ``color-mapping`` - ``array`` - .. code-block:: none Channel to color mapping (or pixel order). For example a GRB channel to color mapping would be color-mapping = ; This property is **required**. .. group-tab:: Deprecated node specific properties Deprecated properties not inherited from the base binding file. (None) .. group-tab:: 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-uart" compatible. .. list-table:: :widths: 1 1 4 :header-rows: 1 * - Name - Type - Details * - ``status`` - ``string`` - .. code-block:: none 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: ``'okay'``, ``'disabled'``, ``'reserved'``, ``'fail'``, ``'fail-sss'`` See :ref:`zephyr:dt-important-props` for more information. * - ``compatible`` - ``string-array`` - .. code-block:: none 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 :ref:`zephyr:dt-important-props` for more information. * - ``reg`` - ``array`` - .. code-block:: none 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 :ref:`zephyr:dt-important-props` for more information. * - ``reg-names`` - ``string-array`` - .. code-block:: none 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" * - ``interrupts`` - ``array`` - .. code-block:: none 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 :ref:`zephyr:dt-important-props` for more information. * - ``interrupts-extended`` - ``compound`` - .. code-block:: none 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. * - ``interrupt-names`` - ``string-array`` - .. code-block:: none 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. * - ``interrupt-parent`` - ``phandle`` - .. code-block:: none 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. * - ``label`` - ``string`` - .. code-block:: none 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 :ref:`zephyr:dt-important-props` for more information. * - ``clocks`` - ``phandle-array`` - .. code-block:: none 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 * - ``clock-names`` - ``string-array`` - .. code-block:: none Optional names given to each clock provider in the "clocks" property. * - ``#address-cells`` - ``int`` - .. code-block:: none This property encodes the number of 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. * - ``#size-cells`` - ``int`` - .. code-block:: none This property encodes the number of 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. * - ``dmas`` - ``phandle-array`` - .. code-block:: none DMA channel specifiers relevant to the device. * - ``dma-names`` - ``string-array`` - .. code-block:: none Optional names given to the DMA channel specifiers in the "dmas" property. * - ``io-channels`` - ``phandle-array`` - .. code-block:: none IO channel specifiers relevant to the device. * - ``io-channel-names`` - ``string-array`` - .. code-block:: none Optional names given to the IO channel specifiers in the "io-channels" property. * - ``mboxes`` - ``phandle-array`` - .. code-block:: none Mailbox / IPM channel specifiers relevant to the device. * - ``mbox-names`` - ``string-array`` - .. code-block:: none Optional names given to the mbox specifiers in the "mboxes" property. * - ``power-domains`` - ``phandle-array`` - .. code-block:: none Power domain specifiers relevant to the device. * - ``power-domain-names`` - ``string-array`` - .. code-block:: none Optional names given to the power domain specifiers in the "power-domains" property. * - ``#power-domain-cells`` - ``int`` - .. code-block:: none Number of cells in power-domains property * - ``hwlocks`` - ``phandle-array`` - .. code-block:: none HW spinlock id relevant to the device. * - ``hwlock-names`` - ``string-array`` - .. code-block:: none Optional names given to the hwlock specifiers in the "hwlocks" property. * - ``zephyr,deferred-init`` - ``boolean`` - .. code-block:: none Do not initialize device automatically on boot. Device should be manually initialized using device_init(). * - ``wakeup-source`` - ``boolean`` - .. code-block:: none 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`` - .. code-block:: none Automatically configure the device for runtime power management after the init function runs. * - ``zephyr,disabling-power-states`` - ``phandles`` - .. code-block:: none List of power states that will disable this device power.