PDM driver

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

Modules
	PDM peripheral driver configuration

Data Structures
struct	nrfx_pdm_evt_t
	PDM event structure. More...
struct	nrfx_pdm_config_t
	PDM interface driver configuration structure. More...

Macros
#define	NRFX_PDM_MAX_BUFFER_SIZE   32767
	Maximum supported PDM buffer size.
#define	NRFX_PDM_DEFAULT_EXTENDED_RATIO_CONFIG   .ratio = NRF_PDM_RATIO_64X,
	PDM additional ratio configuration.
#define	NRFX_PDM_DEFAULT_EXTENDED_MCLKSRC_CONFIG   .mclksrc = NRF_PDM_MCLKSRC_PCLK32M,
	PDM additional master clock source configuration.
#define	NRFX_PDM_DEFAULT_CONFIG(_pin_clk, _pin_din)
	PDM driver default configuration. More...

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

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

Functions
nrfx_err_t	nrfx_pdm_init (nrfx_pdm_config_t const *p_config, nrfx_pdm_event_handler_t event_handler)
	Function for initializing the PDM interface. More...
void	nrfx_pdm_uninit (void)
	Function for uninitializing the PDM interface. More...
NRFX_STATIC_INLINE uint32_t	nrfx_pdm_task_address_get (nrf_pdm_task_t task)
	Function for getting the address of a PDM interface task. More...
NRFX_STATIC_INLINE bool	nrfx_pdm_enable_check (void)
	Function for getting the state of the PDM interface. More...
nrfx_err_t	nrfx_pdm_start (void)
	Function for starting the PDM sampling. More...
nrfx_err_t	nrfx_pdm_stop (void)
	Function for stopping the PDM sampling. More...
nrfx_err_t	nrfx_pdm_buffer_set (int16_t *buffer, uint16_t buffer_length)
	Function for supplying the sample buffer. More...

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, \
 .pin_clk = _pin_clk, \
 .pin_din = _pin_din, \
 .clock_freq = NRF_PDM_FREQ_1032K, \
 .gain_l = NRF_PDM_GAIN_DEFAULT, \
 .gain_r = NRF_PDM_GAIN_DEFAULT, \
 .interrupt_priority = NRFX_PDM_DEFAULT_CONFIG_IRQ_PRIORITY, \
 NRFX_PDM_DEFAULT_EXTENDED_RATIO_CONFIG \
 NRFX_PDM_DEFAULT_EXTENDED_MCLKSRC_CONFIG \
}

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.

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()

nrfx_err_t nrfx_pdm_buffer_set	(	int16_t *	buffer,
		uint16_t	buffer_length
	)

Function for supplying the sample buffer.

Call this function after every buffer request event.

Parameters

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

Return values

NRFX_SUCCESS	The buffer was applied successfully.
NRFX_ERROR_BUSY	The buffer was already supplied or the peripheral is currently being stopped.
NRFX_ERROR_INVALID_STATE	The driver was not initialized.
NRFX_ERROR_INVALID_PARAM	Invalid parameters were provided.

nrfx_pdm_enable_check()

NRFX_STATIC_INLINE bool nrfx_pdm_enable_check

(

void

)

Function for getting the state of the PDM interface.

Return values

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

nrfx_pdm_init()

nrfx_err_t nrfx_pdm_init	(	nrfx_pdm_config_t const *	p_config,
		nrfx_pdm_event_handler_t	event_handler
	)

Function for initializing the PDM interface.

Parameters

[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

NRFX_SUCCESS	Initialization was successful.
NRFX_ERROR_INVALID_STATE	The driver is already initialized.
NRFX_ERROR_INVALID_PARAM	Invalid configuration was specified.

nrfx_pdm_start()

nrfx_err_t nrfx_pdm_start

(

void

)

Function for starting the PDM sampling.

Return values

NRFX_SUCCESS	Sampling was started successfully or was already in progress.
NRFX_ERROR_BUSY	Previous start/stop operation is in progress.

nrfx_pdm_stop()

nrfx_err_t nrfx_pdm_stop

(

void

)

Function for stopping the PDM sampling.

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

Return values

NRFX_SUCCESS	Sampling was stopped successfully or was already stopped before.
NRFX_ERROR_BUSY	Previous start/stop operation is in progress.

nrfx_pdm_task_address_get()

NRFX_STATIC_INLINE uint32_t nrfx_pdm_task_address_get

(

nrf_pdm_task_t

task

)

Function for getting the address of a PDM interface task.

Parameters

[in]

task

Task.

Returns

Task address.

nrfx_pdm_uninit()

void nrfx_pdm_uninit

(

void

)

Function for uninitializing the PDM interface.

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