Pulse Density Modulation (PDM) peripheral driver. More...

Topics
	PDM peripheral driver configuration

Data Structures
struct	nrfx_pdm_evt_t
	PDM event structure. More...

struct	nrfx_pdm_prescalers_t
	PDM prescalers structure. More...

struct	nrfx_pdm_config_t
	PDM interface driver configuration structure. More...

struct	nrfx_pdm_output_t
	PDM output frequency and sampling rate values. More...

struct	nrfx_pdm_t
	Data structure of the Pulse Density Modulation (PDM) driver instance. More...

Macros
#define	NRFX_PDM_MAX_BUFFER_SIZE 32767
	Maximum supported PDM buffer size.

#define	NRFX_PDM_DEFAULT_CONFIG(_pin_clk, _pin_din)
	PDM driver default configuration.

#define	NRFX_PDM_INSTANCE(reg)
	Macro for creating an instance of the PDM driver.

Typedefs
typedef void(*	nrfx_pdm_event_handler_t) (nrfx_pdm_evt_t const *p_evt)
	Handler for the PDM interface ready events.

Enumerations
enum	nrfx_pdm_error_t { NRFX_PDM_NO_ERROR = 0 , NRFX_PDM_ERROR_OVERFLOW = 1 }
	PDM error type. More...

Functions
int	nrfx_pdm_init (nrfx_pdm_t p_instance, nrfx_pdm_config_t const p_config, nrfx_pdm_event_handler_t event_handler)
	Function for initializing the PDM driver instance.

int	nrfx_pdm_reconfigure (nrfx_pdm_t p_instance, nrfx_pdm_config_t const p_config)
	Function for reconfiguring the PDM driver instance.

void	nrfx_pdm_uninit (nrfx_pdm_t *p_instance)
	Function for uninitializing the PDM driver instance.

bool	nrfx_pdm_init_check (nrfx_pdm_t const *p_instance)
	Function for checking if the PDM driver instance is initialized.

NRFX_STATIC_INLINE uint32_t	nrfx_pdm_task_address_get (nrfx_pdm_t const *p_instance, nrf_pdm_task_t task)
	Function for getting the address of a PDM driver instance task.

NRFX_STATIC_INLINE bool	nrfx_pdm_enable_check (nrfx_pdm_t const *p_instance)
	Function for getting the state of the PDM drivers instance.

int	nrfx_pdm_start (nrfx_pdm_t *p_instance)
	Function for starting the PDM sampling.

int	nrfx_pdm_stop (nrfx_pdm_t *p_instance)
	Function for stopping the PDM sampling.

int	nrfx_pdm_buffer_set (nrfx_pdm_t p_instance, int16_t buffer, uint16_t buffer_length)
	Function for supplying the sample buffer.

int	nrfx_pdm_prescalers_calc (nrfx_pdm_output_t const output_config, nrfx_pdm_prescalers_t prescalers)
	Function for calculating PDM clock prescaler values.

void	nrfx_pdm_irq_handler (nrfx_pdm_t *p_instance)
	Driver interrupt handler.

Detailed Description

Pulse Density Modulation (PDM) peripheral driver.

Macro Definition Documentation

◆ NRFX_PDM_DEFAULT_CONFIG

#define NRFX_PDM_DEFAULT_CONFIG	(		_pin_clk,
			_pin_din )

Value:

{                                                                                    \
    .mode               = NRF_PDM_MODE_MONO,                                         \
    .edge               = NRF_PDM_EDGE_LEFTFALLING,                                  \
    .clk_pin            = _pin_clk,                                                  \
    .din_pin            = _pin_din,                                                  \
    .gain_l             = NRF_PDM_GAIN_DEFAULT,                                      \
    .gain_r             = NRF_PDM_GAIN_DEFAULT,                                      \
    .interrupt_priority = NRFX_PDM_DEFAULT_CONFIG_IRQ_PRIORITY,                      \
    .prescalers         =                                                            \
    {                                                                                \
        NRFX_COND_CODE_1(NRF_PDM_HAS_PDMCLKCTRL,                                     \
                     (.clock_freq = NRF_PDM_FREQ_1032K,), ())                        \
        NRFX_COND_CODE_1(NRF_PDM_HAS_PRESCALER,                                      \
                     (.prescaler = 4,), ())                                          \
        NRFX_COND_CODE_1(NRF_PDM_HAS_RATIO_CONFIG,                                   \
                     (.ratio = NRF_PDM_RATIO_64X,), ())                              \
        NRFX_COND_CODE_1(NRF_PDM_HAS_CUSTOM_RATIO,                                   \
                     (.custom_ratio = {                                              \
                                       .ratio = 64,                                  \
                                       .filter_msb = NRF_PDM_FILTER_CIC_MSB_RANGE_5, \
                                       .compensation_gain = 0,                       \
                                       .minor_compensation_gain = false,             \
                                      }), ())                                        \
    },                                                                               \
    NRFX_COND_CODE_1(NRF_PDM_HAS_SELECTABLE_CLOCK,                                   \
                     (.mclksrc = NRF_PDM_MCLKSRC_PCLK32M,), ())                      \
}

PDM driver default configuration.

This configuration sets up PDM with the following options:

mono mode
data sampled on the clock falling edge
frequency: 1.032 MHz
standard gain

Parameters

[in]	_pin_clk	CLK output pin.
[in]	_pin_din	DIN input pin.

◆ NRFX_PDM_INSTANCE

#define NRFX_PDM_INSTANCE ( reg )

Value:

{                                 \
    .p_reg = (NRF_PDM_Type *)reg, \
    .cb = {0}                     \
}

Macro for creating an instance of the PDM driver.

Typedef Documentation

◆ nrfx_pdm_event_handler_t

typedef void(* nrfx_pdm_event_handler_t) (nrfx_pdm_evt_t const *p_evt)

Handler for the PDM interface ready events.

This event handler is called on a buffer request, an error or when a buffer is full and ready to be processed.

Parameters

[in] p_evt Pointer to the PDM event structure.

Enumeration Type Documentation

◆ nrfx_pdm_error_t

enum nrfx_pdm_error_t

PDM error type.

Enumerator
NRFX_PDM_NO_ERROR	No error.
NRFX_PDM_ERROR_OVERFLOW	Overflow error.

Function Documentation

◆ nrfx_pdm_buffer_set()

int nrfx_pdm_buffer_set	(	nrfx_pdm_t *	p_instance,
		int16_t *	buffer,
		uint16_t	buffer_length )

Function for supplying the sample buffer.

Call this function after every buffer request event.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	buffer	Pointer to the receive buffer. Cannot be NULL.
[in]	buffer_length	Length of the receive buffer in 16-bit words.

Return values

0	The buffer was applied successfully.
-EBUSY	The buffer was already supplied or the peripheral is currently being stopped.
-EINPROGRESS	The driver was not initialized.
-EINVAL	Invalid parameters were provided.

◆ nrfx_pdm_enable_check()

NRFX_STATIC_INLINE bool nrfx_pdm_enable_check ( nrfx_pdm_t const * p_instance )

Function for getting the state of the PDM drivers instance.

Parameters

[in] p_instance Pointer to the driver instance structure.

Return values

true	The PDM interface is enabled.
false	The PDM interface is disabled.

◆ nrfx_pdm_init()

int nrfx_pdm_init	(	nrfx_pdm_t *	p_instance,
		nrfx_pdm_config_t const *	p_config,
		nrfx_pdm_event_handler_t	event_handler )

Function for initializing the PDM driver instance.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	p_config	Pointer to the structure with the initial configuration.
[in]	event_handler	Event handler provided by the user. Cannot be NULL.

Return values

0	Initialization was successful.
-EALREADY	The driver is already initialized.
-EINVAL	Invalid configuration was specified.

◆ nrfx_pdm_init_check()

bool nrfx_pdm_init_check ( nrfx_pdm_t const * p_instance )

Function for checking if the PDM driver instance is initialized.

Parameters

[in] p_instance Pointer to the driver instance structure.

Return values

true	Interface is already initialized.
false	Interface is not initialized.

◆ nrfx_pdm_irq_handler()

void nrfx_pdm_irq_handler ( nrfx_pdm_t * p_instance )

Driver interrupt handler.

Parameters

[in] p_instance Pointer to the driver instance structure.

◆ nrfx_pdm_prescalers_calc()

int nrfx_pdm_prescalers_calc	(	nrfx_pdm_output_t const *	output_config,
		nrfx_pdm_prescalers_t *	prescalers )

Function for calculating PDM clock prescaler values.

Call this function to find suitable value for prescalers in nrfx_pdm_config_t structure.

Note: This function does not provide custom ratio configuration, even if the device supports it. Custom ratio configuration has to be provided the by the user.

Parameters

[in]	output_config	Expected output frequencies.
[out]	prescalers	Prescaler structure pointer to be filled with prescaler values.

Return values

0	Suitable prescaler values were found.
-EINVAL	No suitable prescaler values were found.

◆ nrfx_pdm_reconfigure()

int nrfx_pdm_reconfigure	(	nrfx_pdm_t *	p_instance,
		nrfx_pdm_config_t const *	p_config )

Function for reconfiguring the PDM driver instance.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	p_config	Pointer to the structure with the configuration.

Return values

0	Reconfiguration was successful.
-EBUSY	There is ongoing sampling and driver cannot be reconfigured.
-EINPROGRESS	The driver is not initialized.
-EINVAL	Invalid configuration was specified.

◆ nrfx_pdm_start()

int nrfx_pdm_start ( nrfx_pdm_t * p_instance )

Function for starting the PDM sampling.

Parameters

[in] p_instance Pointer to the driver instance structure.

Return values

0	Sampling was started successfully or was already in progress.
-EBUSY	Previous start/stop operation is in progress.

◆ nrfx_pdm_stop()

int nrfx_pdm_stop ( nrfx_pdm_t * p_instance )

Function for stopping the PDM sampling.

When this function is called, the PDM driver instance is stopped after finishing the current frame. The event handler function might be called once more after calling this function.

Parameters

[in] p_instance Pointer to the driver instance structure.

Return values

0	Sampling was stopped successfully or was already stopped before.
-EBUSY	Previous start/stop operation is in progress.

◆ nrfx_pdm_task_address_get()

NRFX_STATIC_INLINE uint32_t nrfx_pdm_task_address_get	(	nrfx_pdm_t const *	p_instance,
		nrf_pdm_task_t	task )

Function for getting the address of a PDM driver instance task.

Parameters

[in]	p_instance	Pointer to the driver instance structure.
[in]	task	Task.

Returns: Task address.

◆ nrfx_pdm_uninit()

void nrfx_pdm_uninit ( nrfx_pdm_t * p_instance )

Function for uninitializing the PDM driver instance.

Parameters

[in] p_instance Pointer to the driver instance structure.

This function stops PDM sampling, if it is in progress.

Topics

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ NRFX_PDM_DEFAULT_CONFIG

◆ NRFX_PDM_INSTANCE

Typedef Documentation

◆ nrfx_pdm_event_handler_t

Enumeration Type Documentation

◆ nrfx_pdm_error_t

Function Documentation

◆ nrfx_pdm_buffer_set()

◆ nrfx_pdm_enable_check()

◆ nrfx_pdm_init()

◆ nrfx_pdm_init_check()

◆ nrfx_pdm_irq_handler()

◆ nrfx_pdm_prescalers_calc()

◆ nrfx_pdm_reconfigure()

◆ nrfx_pdm_start()

◆ nrfx_pdm_stop()

◆ nrfx_pdm_task_address_get()

◆ nrfx_pdm_uninit()