espressif,esp32-adc

Vendor: Espressif Systems

Note

An implementation of a driver matching this compatible is available in drivers/adc/adc_esp32.c.

Description

Espressif ESP32 ADC
Possible available resolutions depends on the used chip.
  - ESP32     < 9,10,11,12 >
  - ESP32-S2  < 12 >
  - ESP32-C3  < 12 >
  - ESP32-S3  < 12 >
For chips with configurable resolution feature (ESP32),
maximum resolution will be used if not set explicitly.

Zephyr API is using gain unit to characterize ADC input.
To achieve compatibility we choose to select those gain,
which corresponds to the ESP32 ADC attenuation feature.

  ESP32,attenuation ~ zephyr,gain
  -----------------   -----------
  0 dB                ADC_GAIN_1
  2.5 dB              ADC_GAIN_4_5
  6 dB                ADC_GAIN_1_2
  11 dB               ADC_GAIN_1_4

In case unsupported gain is selected the adc_channel_setup()
would return ENOTSUP error.

Properties

Top level properties

These property descriptions apply to “espressif,esp32-adc” 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

unit

int

 
ADC unit number. Possible values are 1,2,.. depending on chip.

This property is required.

channel-count

int

 
The maximum channels supported on each unit.

This property is required.

#io-channel-cells

int

This property is required.

Constant value: 1

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-adc” compatible.

Name

Type

Details

#address-cells

int

 
number of address cells in reg property

Constant value: 1

#size-cells

int

 
number of size cells in reg property

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

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.

Child node properties

Name

Type

Details

reg

array

 
Channel identifier.

This property is required.

See Important properties for more information.

zephyr,gain

string

 
Gain selection:
- ADC_GAIN_1_6: x 1/6
- ADC_GAIN_1_5: x 1/5
- ADC_GAIN_1_4: x 1/4
- ADC_GAIN_1_3: x 1/3
- ADC_GAIN_2_5: x 2/5
- ADC_GAIN_1_2: x 1/2
- ADC_GAIN_2_3: x 2/3
- ADC_GAIN_4_5: x 4/5
- ADC_GAIN_1:   x 1
- ADC_GAIN_2:   x 2
- ADC_GAIN_3:   x 3
- ADC_GAIN_4:   x 4
- ADC_GAIN_6:   x 6
- ADC_GAIN_8:   x 8
- ADC_GAIN_12:  x 12
- ADC_GAIN_16:  x 16
- ADC_GAIN_24:  x 24
- ADC_GAIN_32:  x 32
- ADC_GAIN_64:  x 64
- ADC_GAIN_128: x 128

This property is required.

Legal values: 'ADC_GAIN_1_6', 'ADC_GAIN_1_5', 'ADC_GAIN_1_4', 'ADC_GAIN_1_3', 'ADC_GAIN_2_5', 'ADC_GAIN_1_2', 'ADC_GAIN_2_3', 'ADC_GAIN_4_5', 'ADC_GAIN_1', 'ADC_GAIN_2', 'ADC_GAIN_3', 'ADC_GAIN_4', 'ADC_GAIN_6', 'ADC_GAIN_8', 'ADC_GAIN_12', 'ADC_GAIN_16', 'ADC_GAIN_24', 'ADC_GAIN_32', 'ADC_GAIN_64', 'ADC_GAIN_128'

zephyr,reference

string

 
Reference selection:
- ADC_REF_VDD_1:     VDD
- ADC_REF_VDD_1_2:   VDD/2
- ADC_REF_VDD_1_3:   VDD/3
- ADC_REF_VDD_1_4:   VDD/4
- ADC_REF_INTERNAL:  Internal
- ADC_REF_EXTERNAL0: External, input 0
- ADC_REF_EXTERNAL1: External, input 1

This property is required.

Legal values: 'ADC_REF_VDD_1', 'ADC_REF_VDD_1_2', 'ADC_REF_VDD_1_3', 'ADC_REF_VDD_1_4', 'ADC_REF_INTERNAL', 'ADC_REF_EXTERNAL0', 'ADC_REF_EXTERNAL1'

zephyr,vref-mv

int

 
This property can be used to specify the voltage (in millivolts)
of the reference selected for this channel, so that applications
can get that value if needed for some calculations.
For the internal reference, the voltage can be usually obtained with
a dedicated ADC API call, so there is no need to use this property
in that case, but for other references this property can be useful.

zephyr,acquisition-time

int

 
Acquisition time.
Use the ADC_ACQ_TIME macro to compose the value for this property
or pass ADC_ACQ_TIME_DEFAULT to use the default setting for a given
hardware (e.g. when the hardware does not allow to configure the
acquisition time).

This property is required.

zephyr,differential

boolean

 
When set, selects differential input mode for the channel. Otherwise,
single-ended mode is used unless the zephyr,input-negative property is
specified, in which case the differential mode is selected implicitly.

zephyr,input-positive

int

 
Positive ADC input. Used only for drivers that select
the ADC_CONFIGURABLE_INPUTS Kconfig option.

zephyr,input-negative

int

 
Negative ADC input. Used only for drivers that select
the ADC_CONFIGURABLE_INPUTS Kconfig option.
When specified, implies the differential input mode for the channel.

zephyr,resolution

int

 
ADC resolution to be used for the channel.

zephyr,oversampling

int

 
Oversampling setting to be used for the channel.
When specified, each sample is averaged from 2^N conversion results
(where N is the provided value).

zephyr,current-source-pin

uint8-array

 
Output pin selection for the current sources. The actual
interpretation depends on the driver. This is used only for drivers
which select the ADC_CONFIGURABLE_EXCITATION_CURRENT_SOURCE_PIN
Kconfig option.

zephyr,vbias-pins

int

 
Output pin selection for the bias voltage. The actual interpretation
depends on the driver. This is used only for drivers which select
the ADC_CONFIGURABLE_VBIAS_PIN Kconfig option.

Specifier cell names

  • io-channel cells: input