ADC¶
Overview¶
API Reference¶
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group
adc_interface
ADC driver APIs.
Defines
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ADC_ACQ_TIME_MICROSECONDS
¶ Acquisition time is expressed in microseconds.
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ADC_ACQ_TIME_NANOSECONDS
¶ Acquisition time is expressed in nanoseconds.
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ADC_ACQ_TIME_TICKS
¶ Acquisition time is expressed in ADC ticks.
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ADC_ACQ_TIME
(unit, value)¶ Macro for composing the acquisition time value in given units.
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ADC_ACQ_TIME_DEFAULT
¶ Value indicating that the default acquisition time should be used.
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ADC_ACQ_TIME_UNIT
(time)¶
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ADC_ACQ_TIME_VALUE
(time)¶
Typedefs
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typedef enum adc_action (*
adc_sequence_callback
)(const struct device *dev, const struct adc_sequence *sequence, uint16_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.
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typedef int (*
adc_api_channel_setup
)(const 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.
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typedef int (*
adc_api_read
)(const 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
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enum
adc_gain
¶ ADC channel gain factors.
Values:
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enumerator
ADC_GAIN_1_6
¶ x 1/6.
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enumerator
ADC_GAIN_1_5
¶ x 1/5.
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enumerator
ADC_GAIN_1_4
¶ x 1/4.
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enumerator
ADC_GAIN_1_3
¶ x 1/3.
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enumerator
ADC_GAIN_1_2
¶ x 1/2.
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enumerator
ADC_GAIN_2_3
¶ x 2/3.
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enumerator
ADC_GAIN_1
¶ x 1.
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enumerator
ADC_GAIN_2
¶ x 2.
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enumerator
ADC_GAIN_3
¶ x 3.
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enumerator
ADC_GAIN_4
¶ x 4.
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enumerator
ADC_GAIN_8
¶ x 8.
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enumerator
ADC_GAIN_16
¶ x 16.
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enumerator
ADC_GAIN_32
¶ x 32.
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enumerator
ADC_GAIN_64
¶ x 64.
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enumerator
ADC_GAIN_128
¶ x 128.
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enumerator
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enum
adc_reference
¶ ADC references.
Values:
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enumerator
ADC_REF_VDD_1
¶ VDD.
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enumerator
ADC_REF_VDD_1_2
¶ VDD/2.
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enumerator
ADC_REF_VDD_1_3
¶ VDD/3.
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enumerator
ADC_REF_VDD_1_4
¶ VDD/4.
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enumerator
ADC_REF_INTERNAL
¶ Internal.
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enumerator
ADC_REF_EXTERNAL0
¶ External, input 0.
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enumerator
ADC_REF_EXTERNAL1
¶ External, input 1.
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enumerator
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enum
adc_action
¶ Action to be performed after a sampling is done.
Values:
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enumerator
ADC_ACTION_CONTINUE
¶ The sequence should be continued normally.
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enumerator
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.
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enumerator
ADC_ACTION_FINISH
¶ The sequence should be finished immediately.
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enumerator
Functions
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int
adc_gain_invert
(enum adc_gain gain, int32_t *value)¶ Invert the application of gain to a measurement value.
For example, if the gain passed in is ADC_GAIN_1_6 and the referenced value is 10, the value after the function returns is 60.
- Parameters
gain
: the gain used to amplify the input signal.value
: a pointer to a value that initially has the effect of the applied gain but has that effect removed when this function successfully returns. If the gain cannot be reversed the value remains unchanged.
- Return Value
0
: if the gain was successfully reversed-EINVAL
: if the gain could not be interpreted
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int
adc_raw_to_millivolts
(int32_t ref_mv, enum adc_gain gain, uint8_t resolution, int32_t *valp)¶ Convert a raw ADC value to millivolts.
This function performs the necessary conversion to transform a raw ADC measurement to a voltage in millivolts.
- Parameters
ref_mv
: the reference voltage used for the measurement, in millivolts. This may be from adc_ref_internal() or a known external reference.gain
: the ADC gain configuration used to sample the inputresolution
: the number of bits in the absolute value of the sample. For differential sampling this may be one less than the resolution in struct adc_sequence.valp
: pointer to the raw measurement value on input, and the corresponding millivolt value on successful conversion. If conversion fails the stored value is left unchanged.
- Return Value
0
: on successful conversion-EINVAL
: if the gain is not reversible
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int
adc_channel_setup
(const 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.
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int
adc_read
(const 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.
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uint16_t
adc_ref_internal
(const struct device *dev)¶ Get the internal reference voltage.
Returns the voltage corresponding to ADC_REF_INTERNAL, measured in millivolts.
- Return
a positive value is the reference voltage value. Returns zero if reference voltage information is not available.
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struct
adc_channel_cfg
¶ - #include <adc.h>
Structure for specifying the configuration of an ADC channel.
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struct
adc_sequence_options
¶ - #include <adc.h>
Structure defining additional options for an ADC sampling sequence.
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struct
adc_sequence
¶ - #include <adc.h>
Structure defining an ADC sampling sequence.
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struct
adc_driver_api
¶ - #include <adc.h>
ADC driver API.
This is the mandatory API any ADC driver needs to expose.
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