ADC

Overview

API Reference

group adc_interface

ADC driver APIs.

Defines

ADC_ACQ_TIME_MICROSECONDS

Acquisition time is expressed in microseconds.

ADC_ACQ_TIME_NANOSECONDS

Acquisition time is expressed in nanoseconds.

ADC_ACQ_TIME_TICKS

Acquisition time is expressed in ADC ticks.

ADC_ACQ_TIME(unit, value)

Macro for composing the acquisition time value in given units.

ADC_ACQ_TIME_DEFAULT

Value indicating that the default acquisition time should be used.

ADC_ACQ_TIME_UNIT(time)
ADC_ACQ_TIME_VALUE(time)

Typedefs

typedef enum adc_action (*adc_sequence_callback)(struct device *dev, const struct adc_sequence *sequence, u16_t sampling_index)

Type definition of the optional callback function to be called after a requested sampling is done.

Return
Action to be performed by the driver. See adc_action.
Parameters
  • dev: Pointer to the device structure for the driver instance.
  • sequence: Pointer to the sequence structure that triggered the sampling.
  • sampling_index: Index (0-65535) of the sampling done.

typedef int (*adc_api_channel_setup)(struct device *dev, const struct adc_channel_cfg *channel_cfg)

Type definition of ADC API function for configuring a channel. See adc_channel_setup() for argument descriptions.

typedef int (*adc_api_read)(struct device *dev, const struct adc_sequence *sequence)

Type definition of ADC API function for setting a read request. See adc_read() for argument descriptions.

Enums

enum adc_gain

ADC channel gain factors.

Values:

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_1_2

x 1/2.

ADC_GAIN_2_3

x 2/3.

ADC_GAIN_1

x 1.

ADC_GAIN_2

x 2.

ADC_GAIN_3

x 3.

ADC_GAIN_4

x 4.

ADC_GAIN_8

x 8.

ADC_GAIN_16

x 16.

ADC_GAIN_32

x 32.

ADC_GAIN_64

x 64.

enum adc_reference

ADC references.

Values:

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.

enum adc_action

Action to be performed after a sampling is done.

Values:

ADC_ACTION_CONTINUE = 0

The sequence should be continued normally.

ADC_ACTION_REPEAT

The sampling should be repeated. New samples or sample should be read from the ADC and written in the same place as the recent ones.

ADC_ACTION_FINISH

The sequence should be finished immediately.

Functions

int adc_channel_setup(struct device *dev, const struct adc_channel_cfg *channel_cfg)

Configure an ADC channel.

It is required to call this function and configure each channel before it is selected for a read request.

Parameters
  • dev: Pointer to the device structure for the driver instance.
  • channel_cfg: Channel configuration.
Return Value
  • 0: On success.
  • -EINVAL: If a parameter with an invalid value has been provided.

static int z_impl_adc_channel_setup(struct device *dev, const struct adc_channel_cfg *channel_cfg)
int adc_read(struct device *dev, const struct adc_sequence *sequence)

Set a read request.

If invoked from user mode, any sequence struct options for callback must be NULL.

Parameters
  • dev: Pointer to the device structure for the driver instance.
  • sequence: Structure specifying requested sequence of samplings.

Return Value
  • 0: On success.
  • -EINVAL: If a parameter with an invalid value has been provided.
  • -ENOMEM: If the provided buffer is to small to hold the results of all requested samplings.
  • -ENOTSUP: If the requested mode of operation is not supported.
  • -EBUSY: If another sampling was triggered while the previous one was still in progress. This may occur only when samplings are done with intervals, and it indicates that the selected interval was too small. All requested samples are written in the buffer, but at least some of them were taken with an extra delay compared to what was scheduled.

static int z_impl_adc_read(struct device *dev, const struct adc_sequence *sequence)
struct adc_channel_cfg
#include <adc.h>

Structure for specifying the configuration of an ADC channel.

struct adc_sequence_options
#include <adc.h>

Structure defining additional options for an ADC sampling sequence.

struct adc_sequence
#include <adc.h>

Structure defining an ADC sampling sequence.

struct adc_driver_api
#include <adc.h>

ADC driver API.

This is the mandatory API any ADC driver needs to expose.