espressif,esp32-ledc
Vendor: Espressif Systems
Note
An implementation of a driver matching this compatible is available in drivers/pwm/pwm_led_esp32.c.
Description
Espressif's LEDC controller Node
The LEDC controller is primarily designed to control the intensity of LEDs, although it can be
used to generate PWM signals for other purposes as well.
The mapping between the channel and GPIO is done through pinctrl
&ledc0 {
pinctrl-0 = <&ledc0_default>;
pinctrl-names = "default";
}
The 'ledc0_default' node state is defined in <board>-pinctrl.dtsi.
ledc0_default: ledc0_default {
group1 {
pinmux = <LEDC_CH0_GPIO0>,
<LEDC_CH1_GPIO2>,
<LEDC_CH2_GPIO4>;
output-enable;
};
};
If another GPIO mapping is desired, check if <board>-pinctrl.dtsi already have it defined,
otherwise, define the required mapping at your own application folder into a custom
<board>.overlay file.
The 'pinmux' property uses a macro defined in
https://github.com/zephyrproject-rtos/hal_espressif/tree/zephyr/include/dt-bindings/pinctrl
Before including a new node, check if the desired mapping is available according to the SoC.
As an example, the 'ledc0_custom' state below illustrates an alternate mapping using another set
of channels and pins in a custom overlay file.
&pinctrl {
ledc0_custom: ledc0_custom {
group1 {
pinmux = <LEDC_CH0_GPIO0>,
<LEDC_CH9_GPIO2>,
<LEDC_CH10_GPIO4>;
output-enable;
};
};
};
Use the child bindings to configure the desired channel:
&ledc0 {
pinctrl-0 = <&ledc0_custom>;
pinctrl-names = "default";
status = "okay";
#address-cells = <1>;
#size-cells = <0>;
channel0@0 {
reg = <0x0>;
timer = <0>;
};
channel9@9 {
reg = <0x9>;
timer = <0>;
inverted;
};
channel10@a {
reg = <0xa>;
timer = <1>;
};
};
For the channel to be initially inverted after the driver's init, the flag 'inverted' can
be declared, as shown above for channel 9.
Note: The channel's 'reg' property defines the ID of the channel. It must match the channel used
in the 'pinmux'.
Properties
Top level properties
These property descriptions apply to “espressif,esp32-ledc” nodes themselves. This page also describes child node properties in the following sections.
Node specific properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
|---|---|---|
|
|
Number of items to expect in a pwm specifier
This property is required. Constant value: |
|
|
Pin configuration/s for the first state. Content is specific to the
selected pin controller driver implementation.
|
|
|
Pin configuration/s for the second state. See pinctrl-0.
|
|
|
Pin configuration/s for the third state. See pinctrl-0.
|
|
|
Pin configuration/s for the fourth state. See pinctrl-0.
|
|
|
Pin configuration/s for the fifth state. See pinctrl-0.
|
|
|
Names for the provided states. The number of names needs to match the
number of states.
|
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 “espressif,esp32-ledc” 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.
|
Child node properties
Name |
Type |
Details |
|---|---|---|
|
|
The ESP32 has 8 low speed channel and 8 high speed channels.
The low speed channel are mapped from channel 0 to 7, and the high speed are mapped from
channel 8 to 15.
High speed channels are only available in the ESP32 SoC. ESP32S2 and ESP32S3 have 8
available channels, and ESP32C3 has 6. In these SoCs there is no differentiation between
low or high speed.
This property is required. Legal values: See Important properties for more information. |
|
|
Timer selection.
For maximum flexibility, the high-speed as well as the low-speed channels can be driven from
one of four high-speed/low-speed timers.
This property is required. Legal values: |
|
|
Initial channel output level.
This flag defines if the channel will remain initially inverted after driver init,
as any pwm_set() operation will re-evaluate if the output is inverted or not
according to the flag passed as parameter.
|
Specifier cell names
pwm cells: channel, period, flags