Successive Approximation Analog-to-Digital Converter (SAADC) peripheral driver. More...

Topics
	SAADC peripheral driver configuration

Data Structures
struct	nrfx_saadc_channel_t
	SAADC channel configuration structure. More...

struct	nrfx_saadc_adv_config_t
	SAADC driver advanced mode configuration structure. More...

struct	nrfx_saadc_done_evt_t
	SAADC driver done event data. More...

struct	nrfx_saadc_limit_evt_t
	SAADC driver limit event data. More...

struct	nrfx_saadc_evt_t
	SAADC driver event structure. More...

Macros
#define	NRFX_SAADC_DEFAULT_ACQTIME NRF_SAADC_ACQTIME_10US
	Auxiliary symbol specifying default value for the SAADC acquisition time.

#define	NRFX_SAADC_DEFAULT_CONV_TIME 7
	Auxiliary symbol specifying default value for the SAADC conversion time.

#define	NRFX_SAADC_INTERNAL_TIMER_INTERVAL_MAX_US 128U
	Maximum value of the internal timer interval in microseconds.

#define	NRFX_SAADC_REF_INTERNAL_VALUE NRFX_ANALOG_REF_INTERNAL_VAL
	Symbol specifying internal reference voltage.

#define	NRFX_SAADC_DEFAULT_CHANNEL_SE(_pin_p, _index)
	SAADC channel default configuration for the single-ended mode.

#define	NRFX_SAADC_DEFAULT_CHANNEL_DIFFERENTIAL(_pin_p, _pin_n, _index)
	SAADC channel default configuration for the differential mode.

#define	NRFX_SAADC_SAMPLES_TO_BYTES(_samples)
	Macro for getting number of bytes needed to store specified number of SAADC samples.

#define	NRFX_SAADC_SAMPLE_GET(_samples, _index)
	Macro for getting specified SAADC sample from the filled buffer.

#define	NRFX_SAADC_DEFAULT_ADV_CONFIG
	SAADC driver advanced mode default configuration.

Typedefs
typedef void(*	nrfx_saadc_event_handler_t) (nrfx_saadc_evt_t const *p_event)
	SAADC driver event handler.

Enumerations
enum	nrfx_saadc_evt_type_t { NRFX_SAADC_EVT_DONE , NRFX_SAADC_EVT_LIMIT , NRFX_SAADC_EVT_CALIBRATEDONE , NRFX_SAADC_EVT_BUF_REQ , NRFX_SAADC_EVT_READY , NRFX_SAADC_EVT_FINISHED }
	SAADC driver event types. More...

Functions
int	nrfx_saadc_init (uint8_t interrupt_priority)
	Function for initializing the SAADC driver.

void	nrfx_saadc_uninit (void)
	Function for uninitializing the SAADC driver.

bool	nrfx_saadc_init_check (void)
	Function for checking if the SAADC driver is initialized.

uint16_t	nrfx_saadc_interval_to_cc (uint16_t interval_us)
	Function for getting the internal timer CC value from the interval in microseconds.

int	nrfx_saadc_channels_config (nrfx_saadc_channel_t const *p_channels, uint32_t channel_count)
	Function for configuring multiple SAADC channels.

int	nrfx_saadc_channel_config (nrfx_saadc_channel_t const *p_channel)
	Function for configuring single SAADC channel.

uint32_t	nrfx_saadc_channels_configured_get (void)
	Function for getting the currently configured SAADC channels.

int	nrfx_saadc_channels_deconfig (uint32_t channel_mask)
	Function for deconfiguring the specified SAADC channels.

int	nrfx_saadc_simple_mode_set (uint32_t channel_mask, nrf_saadc_resolution_t resolution, nrf_saadc_oversample_t oversampling, nrfx_saadc_event_handler_t event_handler)
	Function for setting the SAADC driver in the simple mode.

int	nrfx_saadc_advanced_mode_set (uint32_t channel_mask, nrf_saadc_resolution_t resolution, nrfx_saadc_adv_config_t const *p_config, nrfx_saadc_event_handler_t event_handler)
	Function for setting the SAADC driver in the advanced mode.

int	nrfx_saadc_buffer_set (nrf_saadc_value_t *p_buffer, uint16_t size)
	Function for supplying the buffer to be used in the next part of the conversion.

int	nrfx_saadc_mode_trigger (void)
	Function for triggering the conversion in the configured mode.

void	nrfx_saadc_abort (void)
	Function for aborting the ongoing and buffered conversions.

int	nrfx_saadc_limits_set (uint8_t channel, int16_t limit_low, int16_t limit_high)
	Function for setting the SAADC channel limits.

int	nrfx_saadc_offset_calibrate (nrfx_saadc_event_handler_t calib_event_handler)
	Function for starting the SAADC offset calibration.

Detailed Description

Successive Approximation Analog-to-Digital Converter (SAADC) peripheral driver.

Macro Definition Documentation

◆ NRFX_SAADC_DEFAULT_ADV_CONFIG

#define NRFX_SAADC_DEFAULT_ADV_CONFIG

Value:

{                                                                               \
    .oversampling      = NRF_SAADC_OVERSAMPLE_DISABLED,                         \
    .burst             = NRF_SAADC_BURST_DISABLED,                              \
    .internal_timer_cc = 0,                                                     \
    .start_on_end      = false,                                                 \
}

SAADC driver advanced mode default configuration.

This configuration sets up advanced mode of the SAADC driver with the following options:

oversampling disabled
burst disabled
internal sampling timer disabled
triggering of the START task on the END event disabled

Parameters

[in]	_pin_p	Positive input analog pin.
[in]	_pin_n	Negative input analog pin.
[in]	_index	Channel index.

See also: nrfx_saadc_adv_config_t

◆ NRFX_SAADC_DEFAULT_CHANNEL_DIFFERENTIAL

#define NRFX_SAADC_DEFAULT_CHANNEL_DIFFERENTIAL	(	_pin_p,
		_pin_n,
		_index )

Value:

{                                                                       \
    .channel_config =                                                   \
    {                                                                   \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_CONFIG_RES,                   \
                         (.resistor_p = NRF_SAADC_RESISTOR_DISABLED,    \
                          .resistor_n = NRF_SAADC_RESISTOR_DISABLED,),  \
                         ())                                            \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_GAIN,                         \
                         (.gain = NRF_SAADC_GAIN1,),                    \
                         ())                                            \
        .reference  = NRF_SAADC_REFERENCE_INTERNAL,                     \
        .acq_time   = NRFX_SAADC_DEFAULT_ACQTIME,                       \
        .mode       = NRF_SAADC_MODE_DIFFERENTIAL,                      \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_BURST,                        \
                         (.burst = NRF_SAADC_BURST_DISABLED,),          \
                         ())                                            \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_CHOPPING,                     \
                         (.chopping = NRF_SAADC_CHOPPING_DISABLED,),    \
                         ())                                            \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_HIGHSPEED,                    \
                         (.highspeed = NRF_SAADC_HIGHSPEED_DISABLED,),  \
                         ())                                            \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CONVTIME,                        \
                         (.conv_time = NRFX_SAADC_DEFAULT_CONV_TIME,),  \
                         ())                                            \
    },                                                                  \
    .pin_p          = (nrfx_analog_input_t)_pin_p,                      \
    .pin_n          = (nrfx_analog_input_t)_pin_n,                      \
    .channel_index  = _index,                                           \
}

SAADC channel default configuration for the differential mode.

This configuration sets up differential SAADC channel with the following options:

resistor ladder disabled
gain: 1/6
reference voltage: internal
sample acquisition time: 10 us
burst disabled

Parameters

[in]	_pin_p	Positive input analog pin.
[in]	_pin_n	Negative input analog pin.
[in]	_index	Channel index.

See also: nrfx_saadc_channel_t

◆ NRFX_SAADC_DEFAULT_CHANNEL_SE

#define NRFX_SAADC_DEFAULT_CHANNEL_SE	(		_pin_p,
			_index )

Value:

{                                                                      \
    .channel_config =                                                  \
    {                                                                  \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_CONFIG_RES,                  \
                         (.resistor_p = NRF_SAADC_RESISTOR_DISABLED,   \
                          .resistor_n = NRF_SAADC_RESISTOR_DISABLED,), \
                         ())                                           \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_GAIN,                        \
                         (.gain = NRF_SAADC_GAIN1,),                   \
                         ())                                           \
        .reference  = NRF_SAADC_REFERENCE_INTERNAL,                    \
        .acq_time   = NRFX_SAADC_DEFAULT_ACQTIME,                      \
        .mode       = NRF_SAADC_MODE_SINGLE_ENDED,                     \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_BURST,                       \
                         (.burst = NRF_SAADC_BURST_DISABLED,),         \
                         ())                                           \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_CHOPPING,                    \
                         (.chopping = NRF_SAADC_CHOPPING_DISABLED,),   \
                         ())                                           \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CH_HIGHSPEED,                   \
                         (.highspeed = NRF_SAADC_HIGHSPEED_DISABLED,), \
                         ())                                           \
        NRFX_COND_CODE_1(NRF_SAADC_HAS_CONVTIME,                       \
                         (.conv_time = NRFX_SAADC_DEFAULT_CONV_TIME,), \
                         ())                                           \
    },                                                                 \
    .pin_p          = (nrfx_analog_input_t)_pin_p,                     \
    .pin_n          = NRFX_ANALOG_INPUT_DISABLED,                      \
    .channel_index  = _index,                                          \
}

SAADC channel default configuration for the single-ended mode.

This configuration sets up single-ended SAADC channel with the following options:

resistor ladder disabled
gain: 1
reference voltage: internal
sample acquisition time: 10 us
burst disabled

Parameters

[in]	_pin_p	Positive input analog pin.
[in]	_index	Channel index.

See also: nrfx_saadc_channel_t

◆ NRFX_SAADC_SAMPLE_GET

#define NRFX_SAADC_SAMPLE_GET	(		_samples,
			_index )

Value:

(((int16_t *)(_samples))[(_index)])

Macro for getting specified SAADC sample from the filled buffer.

Parameters

[in]	_samples	Pointer to the buffer filled with SAADC samples.
[in]	_index	Sample index.

Returns: Specified sample.

◆ NRFX_SAADC_SAMPLES_TO_BYTES

#define NRFX_SAADC_SAMPLES_TO_BYTES ( _samples )

Value:

(_samples * 2)

Macro for getting number of bytes needed to store specified number of SAADC samples.

Parameters

[in] _samples Number of samples.

Returns: Number of bytes needed to store specified number of samples.

Typedef Documentation

◆ nrfx_saadc_event_handler_t

typedef void(* nrfx_saadc_event_handler_t) (nrfx_saadc_evt_t const *p_event)

SAADC driver event handler.

When operating in the advanced mode:

when the sampling is performed by the external timer, the external timer can be safely started on NRFX_SAADC_EVT_READY and stopped on NRFX_SAADC_EVT_FINISHED.
call the nrfx_saadc_buffer_set() on NRFX_SAADC_EVT_BUF_REQ to achieve the continuous conversion.

Parameters

[in] p_event Pointer to an SAADC driver event. The event structure is allocated on the stack, so it is valid only within the context of the event handler.

Enumeration Type Documentation

◆ nrfx_saadc_evt_type_t

enum nrfx_saadc_evt_type_t

SAADC driver event types.

Enumerator
NRFX_SAADC_EVT_DONE	Event generated when the buffer is filled with samples.
NRFX_SAADC_EVT_LIMIT	Event generated when one of the limits is reached.
NRFX_SAADC_EVT_CALIBRATEDONE	Event generated when the calibration is complete.
NRFX_SAADC_EVT_BUF_REQ	Event generated when the next buffer for continuous conversion is requested.
NRFX_SAADC_EVT_READY	Event generated when the first buffer is acquired by the peripheral and sampling can be started.
NRFX_SAADC_EVT_FINISHED	Event generated when all supplied buffers are filled with results.

Function Documentation

◆ nrfx_saadc_abort()

void nrfx_saadc_abort ( void )

Function for aborting the ongoing and buffered conversions.

Warning: Aborting blocking conversion or calibration from different context is not supported. Perform the operation in non-blocking manner instead.

Note: NRFX_SAADC_EVT_DONE event will be generated if there is a conversion in progress. Event will contain number of words in the sample buffer.

◆ nrfx_saadc_advanced_mode_set()

int nrfx_saadc_advanced_mode_set	(	uint32_t	channel_mask,
		nrf_saadc_resolution_t	resolution,
		nrfx_saadc_adv_config_t const *	p_config,
		nrfx_saadc_event_handler_t	event_handler )

Function for setting the SAADC driver in the advanced mode.

The advanced mode allows performing double-buffered conversions of arbitrary length. The conversions can be done in a blocking or non-blocking manner. When performing conversions in the non-blocking manner and nrfx_saadc_adv_config_t::internal_timer_cc is set to 0, sampling needs to be done by triggering NRF_SAADC_TASK_SAMPLE externally (for example by using the TIMER and/or the PPI/DPPI). When performing conversions in the non-blocking manner and nrfx_saadc_adv_config_t::start_on_end is false, the NRF_SAADC_TASK_START needs to be triggered on NRF_SAADC_EVENT_END externally (for example by using the PPI/DPPI). If nrfx_saadc_adv_config_t::start_on_end is true, the NRF_SAADC_TASK_START is triggered by the driver in the interrupt context or by the hardware using dedicated shorts, if available. Sampling is initiated by calling nrfx_saadc_mode_trigger(). In case of performing conversions in the blocking manner, nrfx_saadc_mode_trigger() may need to be called several times as each call sample each requested channel once.

Note: Unless NRF_SAADC_HAS_INTERNAL_TIMER_SCAN is set, the internal timer can only be used when a single input channel is enabled. When the symbol is set, the internal timer can also be used with multiple channels enabled (scan mode).; The internal timer can only be used in the non-blocking mode.

Parameters

[in]	channel_mask	Bitmask of channels to be used in the advanced mode.
[in]	resolution	Resolution configuration.
[in]	p_config	Pointer to the structure with the advanced mode configuration.
[in]	event_handler	Event handler provided by the user. In case of providing NULL, the conversion will be performed in the blocking manner.

Return values

0	Initialization was successful.
-EBUSY	There is a conversion or calibration ongoing.
-EINVAL	Attempt to activate channel that is not configured.
-ENOTSUP	Attempt to activate either of the following: internal timer in the blocking mode, internal timer with multiple channels enabled when NRF_SAADC_HAS_INTERNAL_TIMER_SCAN is not set, oversampling without burst with multiple channels enabled.

◆ nrfx_saadc_buffer_set()

int nrfx_saadc_buffer_set	(	nrf_saadc_value_t *	p_buffer,
		uint16_t	size )

Function for supplying the buffer to be used in the next part of the conversion.

Parameters

[in]	p_buffer	Pointer to the buffer to be filled with conversion results.
[in]	size	Number of samples in the buffer.

Return values

0	Buffer was supplied successfully.
-EACCES	The provided buffer is not in the Data RAM region.
-E2BIG	The provided buffer is not aligned to the number of activated channels or is too long for the EasyDMA to handle.
-EINPROGRESS	The driver is in the idle mode.
-EALREADY	Both buffers for double-buffered conversions are already set.

◆ nrfx_saadc_channel_config()

int nrfx_saadc_channel_config ( nrfx_saadc_channel_t const * p_channel )

Function for configuring single SAADC channel.

Note: The values of the nrf_saadc_channel_config_t::burst fields in channel configurations are ignored. They will be overridden with the value suitable for the selected driver operation mode.

Warning: This function overrides previous configuration done on specified channel by nrfx_saadc_channels_config or nrfx_saadc_channel_config.

Parameters

[in] p_channel Pointer to the channel configuration structure.

Return values

0	Configuration was successful.
-EBUSY	There is a conversion or calibration ongoing.
-EINVAL	Attempt to configure an invalid analog pin.

◆ nrfx_saadc_channels_config()

int nrfx_saadc_channels_config	(	nrfx_saadc_channel_t const *	p_channels,
		uint32_t	channel_count )

Function for configuring multiple SAADC channels.

Note: The values of the nrf_saadc_channel_config_t::burst fields in channel configurations are ignored. They will be overridden with the value suitable for the selected driver operation mode.; The desired mode (simple or advanced) must be set after the channels are configured.

Warning: This function overrides previous configuration done on any channel by nrfx_saadc_channels_config or nrfx_saadc_channel_config.

Parameters

[in]	p_channels	Pointer to the array of channel configuration structures.
[in]	channel_count	Number of channels to be configured.

Return values

0	Configuration was successful.
-EBUSY	There is a conversion or calibration ongoing.
-EINVAL	Attempt to configure the same channel more than once or attempt to configure an invalid analog pin.

◆ nrfx_saadc_channels_configured_get()

uint32_t nrfx_saadc_channels_configured_get ( void )

Function for getting the currently configured SAADC channels.

Returns: Bitmask of configured channels.

◆ nrfx_saadc_channels_deconfig()

int nrfx_saadc_channels_deconfig ( uint32_t channel_mask )

Function for deconfiguring the specified SAADC channels.

Warning: Pins associated with the deconfigured channels will be released after next nrfx_saadc_simple_mode_set() or nrfx_saadc_advanced_mode_set() call.

Parameters

[in] channel_mask Bitmask of channels to be deconfigured.

Return values

0	Deconfiguration was successful.
-EBUSY	There is a conversion or calibration ongoing.

◆ nrfx_saadc_init()

int nrfx_saadc_init ( uint8_t interrupt_priority )

Function for initializing the SAADC driver.

Parameters

[in] interrupt_priority Interrupt priority.

Return values

0	Initialization was successful.
-EALREADY	The driver is already initialized.

◆ nrfx_saadc_init_check()

bool nrfx_saadc_init_check ( void )

Function for checking if the SAADC driver is initialized.

Return values

true	Driver is already initialized.
false	Driver is not initialized.

◆ nrfx_saadc_interval_to_cc()

uint16_t nrfx_saadc_interval_to_cc ( uint16_t interval_us )

Function for getting the internal timer CC value from the interval in microseconds.

Note: The internal timer runs at 16 MHz, so to convert the interval in microseconds to the internal timer CC value, we can use the formula: interval_cc = interval_us * 16 MHz where 16 MHz is the frequency of the internal timer.; The maximum value for interval_cc is 2047, which corresponds to approximately 7816 Hz ~ 128us. The minimum value for interval_cc depends on the SoC.

Parameters

[in] interval_us The interval in microseconds to be converted.

Returns: The internal timer CC value.

◆ nrfx_saadc_limits_set()

int nrfx_saadc_limits_set	(	uint8_t	channel,
		int16_t	limit_low,
		int16_t	limit_high )

Function for setting the SAADC channel limits.

When limits are enabled and the conversion result exceeds the defined bounds, the handler function is called with the corresponding event as parameter.

Note: Before the limits are set, the driver operation mode (simple or advanced) has to be configured. Only non-blocking conversions can be monitored.; Changing of the driver operation mode disables all configured limits.

Parameters

[in]	channel	Channel index.
[in]	limit_low	Limit low value to generate interrupt. Use `INT16_MIN` to disable interrupt generation.
[in]	limit_high	Limit high value to generate interrupt. Use `INT16_MAX` to disable interrupt generation.

Return values

0	Requested channel limits were set.
-EINVAL	Attempt to activate the limits on disabled channel.
-EPERM	Attempt to activate the limits for blocking conversions.
-EINPROGRESS	Attempt to activate the limits without configured mode.

◆ nrfx_saadc_mode_trigger()

int nrfx_saadc_mode_trigger ( void )

Function for triggering the conversion in the configured mode.

Return values

0	Operation finished successfully in the blocking manner or started successfully in the non-blocking manner.
-EBUSY	The driver is performing the conversion in the advanced blocking mode. Call the function again to continue the conversion.
-ENOMEM	There is no buffer provided. Supply the buffer using nrfx_saadc_buffer_set() and try again.
-EINPROGRESS	There is an ongoing conversion or calibration being performed in the non-blocking manner or the driver is in the idle mode.

◆ nrfx_saadc_offset_calibrate()

int nrfx_saadc_offset_calibrate ( nrfx_saadc_event_handler_t calib_event_handler )

Function for starting the SAADC offset calibration.

Parameters

[in] calib_event_handler Calibration event handler provided by the user. In case of providing NULL, the calibration will be performed in the blocking manner.

Return values

0	Calibration finished successfully in the blocking manner or started successfully in the non-blocking manner.
-EBUSY	There is a conversion or calibration ongoing.

◆ nrfx_saadc_simple_mode_set()

int nrfx_saadc_simple_mode_set	(	uint32_t	channel_mask,
		nrf_saadc_resolution_t	resolution,
		nrf_saadc_oversample_t	oversampling,
		nrfx_saadc_event_handler_t	event_handler )

Function for setting the SAADC driver in the simple mode.

The simple mode allows obtaining a single sample from each requested channel. The conversion can be done in a blocking or non-blocking manner. Sampling is initiated by calling nrfx_saadc_mode_trigger() once.

Parameters

[in]	channel_mask	Bitmask of channels to be used in the simple mode.
[in]	resolution	Resolution configuration.
[in]	oversampling	Oversampling configuration.
[in]	event_handler	Event handler provided by the user. In case of providing NULL, the conversion will be performed in the blocking manner.

Return values

0	Initialization was successful.
-EBUSY	There is a conversion or calibration ongoing.
-EINVAL	Attempt to activate channel that is not configured.

◆ nrfx_saadc_uninit()

void nrfx_saadc_uninit ( void )

Function for uninitializing the SAADC driver.

This function stops all ongoing conversions and disables all channels.

Topics

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ NRFX_SAADC_DEFAULT_ADV_CONFIG

◆ NRFX_SAADC_DEFAULT_CHANNEL_DIFFERENTIAL

◆ NRFX_SAADC_DEFAULT_CHANNEL_SE

◆ NRFX_SAADC_SAMPLE_GET

◆ NRFX_SAADC_SAMPLES_TO_BYTES

Typedef Documentation

◆ nrfx_saadc_event_handler_t

Enumeration Type Documentation

◆ nrfx_saadc_evt_type_t

Function Documentation

◆ nrfx_saadc_abort()

◆ nrfx_saadc_advanced_mode_set()

◆ nrfx_saadc_buffer_set()

◆ nrfx_saadc_channel_config()

◆ nrfx_saadc_channels_config()

◆ nrfx_saadc_channels_configured_get()

◆ nrfx_saadc_channels_deconfig()

◆ nrfx_saadc_init()

◆ nrfx_saadc_init_check()

◆ nrfx_saadc_interval_to_cc()

◆ nrfx_saadc_limits_set()

◆ nrfx_saadc_mode_trigger()

◆ nrfx_saadc_offset_calibrate()

◆ nrfx_saadc_simple_mode_set()

◆ nrfx_saadc_uninit()