DMIC Interface

Detailed Description

Interface for DMIC audio communication.

Summary

The DMIC (Digital Microphone) interface provides APIs and definitions for DMIC audio communication.

Data Structures
struct	dmic_callback_args_t
struct	dmic_status_t
struct	dmic_cfg_t
struct	dmic_api_t
struct	dmic_instance_t

Typedefs
typedef void	dmic_ctrl_t

Enumerations
enum	dmic_direction_t
enum	dmic_mode_t
enum	dmic_delay_t
enum	dmic_event_t
enum	dmic_mute_t
enum	dmic_state_t

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Data Structure Documentation

dmic_callback_args_t

struct dmic_callback_args_t

Callback function parameter data

Data Fields
void const *	p_context	Placeholder for user data. Set in dmic_api_t::open function in dmic_cfg_t.
dmic_event_t	event	The event can be used to identify what caused the callback (overflow or error).

dmic_status_t

struct dmic_status_t

DMIC status.

Data Fields
dmic_state_t	state	Current DMIC state.

dmic_cfg_t

struct dmic_cfg_t

User configuration structure, used in open function

Data Fields
uint32_t	channel
dmic_direction_t	direction
	DMIC direction.
dmic_mode_t	mode
	DMIC operation mode.
dmic_delay_t	delay
	DMIC internal delay.
bool	swap_channel
	DMIC L/R channel swap.
uint32_t	clk_frequency
	DMIC clock.
transfer_instance_t const *	p_transfer_rx
void(*	p_callback )(dmic_callback_args_t *p_args)
void const *	p_context
void const *	p_extend
	Extension parameter for hardware specific settings.
uint8_t	rxi_ipl
	Receive interrupt priority.
uint8_t	idle_err_ipl
	Idle/Error interrupt priority.
IRQn_Type	rxi_irq
	Receive IRQ number.
IRQn_Type	int_irq
	Idle/Error IRQ number.

Field Documentation

channel

uint32_t dmic_cfg_t::channel

Select a channel corresponding to the channel number of the hardware.

p_transfer_rx

transfer_instance_t const* dmic_cfg_t::p_transfer_rx

To use DMA for receiving link a Transfer instance here. Set to NULL if unused.

p_callback

void(* dmic_cfg_t::p_callback) (dmic_callback_args_t *p_args)

Callback provided when an DMIC ISR occurs. Set to NULL for no CPU interrupt.

p_context

void const* dmic_cfg_t::p_context

Placeholder for user data. Passed to the user callback in dmic_callback_args_t.

dmic_api_t

struct dmic_api_t

DMIC functions implemented at the HAL layer will follow this API.

Data Fields
fsp_err_t(*	open )(dmic_ctrl_t *const p_ctrl, dmic_cfg_t const *const p_cfg)
fsp_err_t(*	stop )(dmic_ctrl_t *const p_ctrl)
fsp_err_t(*	mute )(dmic_ctrl_t *const p_ctrl, dmic_mute_t const mute_enable)
fsp_err_t(*	write )(dmic_ctrl_t *const p_ctrl, void const *const p_src, uint32_t const bytes)
fsp_err_t(*	read )(dmic_ctrl_t *const p_ctrl, void *const p_dest, uint32_t const bytes)
fsp_err_t(*	writeRead )(dmic_ctrl_t *const p_ctrl, void const *const p_src, void *const p_dest, uint32_t const bytes)
fsp_err_t(*	statusGet )(dmic_ctrl_t *const p_ctrl, dmic_status_t *const p_status)
fsp_err_t(*	close )(dmic_ctrl_t *const p_ctrl)
fsp_err_t(*	callbackSet )(dmic_ctrl_t *const p_ctrl, void(*p_callback)(dmic_callback_args_t *), void const *const p_context, dmic_callback_args_t *const p_callback_memory)

Field Documentation

open

fsp_err_t(* dmic_api_t::open) (dmic_ctrl_t *const p_ctrl, dmic_cfg_t const *const p_cfg)

Initial configuration.

Precondition

Peripheral clocks and any required output pins should be configured prior to calling this function.

Note

To reconfigure after calling this function, call dmic_api_t::close first.

Parameters

[in]	p_ctrl	Pointer to control block. Must be declared by user. Elements set here.
[in]	p_cfg	Pointer to configuration structure. All elements of this structure must be set by user.

stop

fsp_err_t(* dmic_api_t::stop) (dmic_ctrl_t *const p_ctrl)

Stop communication. Communication is stopped when callback is called with DMIC_EVENT_IDLE.

Parameters

[in]

p_ctrl

Control block set in dmic_api_t::open call for this instance.

mute

fsp_err_t(* dmic_api_t::mute) (dmic_ctrl_t *const p_ctrl, dmic_mute_t const mute_enable)

Enable or disable mute.

Parameters

[in]	p_ctrl	Control block set in dmic_api_t::open call for this instance.
[in]	mute_enable	Whether to enable or disable mute.

write

fsp_err_t(* dmic_api_t::write) (dmic_ctrl_t *const p_ctrl, void const *const p_src, uint32_t const bytes)

Write DMIC data. All transmit data is queued when callback is called with DMIC_EVENT_TX_EMPTY. Transmission is complete when callback is called with DMIC_EVENT_IDLE.

Parameters

[in]	p_ctrl	Control block set in dmic_api_t::open call for this instance.
[in]	p_src	Buffer of PCM samples. Must be 4 byte aligned.
[in]	bytes	Number of bytes in the buffer. Recommended requesting a multiple of 8 bytes. If not a multiple of 8, padding 0s will be added to transmission to make it a multiple of 8.

read

fsp_err_t(* dmic_api_t::read) (dmic_ctrl_t *const p_ctrl, void *const p_dest, uint32_t const bytes)

Read DMIC data. Reception is complete when callback is called with DMIC_EVENT_RX_EMPTY.

Parameters

[in]	p_ctrl	Control block set in dmic_api_t::open call for this instance.
[in]	p_dest	Buffer to store PCM samples. Must be 4 byte aligned.
[in]	bytes	Number of bytes in the buffer. Recommended requesting a multiple of 8 bytes. If not a multiple of 8, receive will stop at the multiple of 8 below requested bytes.

writeRead

fsp_err_t(* dmic_api_t::writeRead) (dmic_ctrl_t *const p_ctrl, void const *const p_src, void *const p_dest, uint32_t const bytes)

Simultaneously write and read DMIC data. Transmission and reception are complete when callback is called with DMIC_EVENT_IDLE.

Parameters

[in]	p_ctrl	Control block set in dmic_api_t::open call for this instance.
[in]	p_src	Buffer of PCM samples. Must be 4 byte aligned.
[in]	p_dest	Buffer to store PCM samples. Must be 4 byte aligned.
[in]	bytes	Number of bytes in the buffers. Recommended requesting a multiple of 8 bytes. If not a multiple of 8, padding 0s will be added to transmission to make it a multiple of 8, and receive will stop at the multiple of 8 below requested bytes.

statusGet

fsp_err_t(* dmic_api_t::statusGet) (dmic_ctrl_t *const p_ctrl, dmic_status_t *const p_status)

Get current status and store it in provided pointer p_status.

Parameters

[in]	p_ctrl	Control block set in dmic_api_t::open call for this instance.
[out]	p_status	Current status of the driver.

close

fsp_err_t(* dmic_api_t::close) (dmic_ctrl_t *const p_ctrl)

Allows driver to be reconfigured and may reduce power consumption.

Parameters

[in]

p_ctrl

Control block set in dmic_api_t::open call for this instance.

callbackSet

fsp_err_t(* dmic_api_t::callbackSet) (dmic_ctrl_t *const p_ctrl, void(*p_callback)(dmic_callback_args_t *), void const *const p_context, dmic_callback_args_t *const p_callback_memory)

Specify callback function and optional context pointer and working memory pointer.

Parameters

[in]	p_ctrl	Pointer to the DMIC control block.
[in]	p_callback	Callback function
[in]	p_context	Pointer to send to callback function
[in]	p_working_memory	Pointer to volatile memory where callback structure can be allocated. Callback arguments allocated here are only valid during the callback.

dmic_instance_t

struct dmic_instance_t

This structure encompasses everything that is needed to use an instance of this interface.

Data Fields
dmic_ctrl_t *	p_ctrl	Pointer to the control structure for this instance.
dmic_cfg_t const *	p_cfg	Pointer to the configuration structure for this instance.
dmic_api_t const *	p_api	Pointer to the API structure for this instance.

Typedef Documentation

dmic_ctrl_t

typedef void dmic_ctrl_t

DMIC control block. Allocate an instance specific control block to pass into the DMIC API calls.

Enumeration Type Documentation

dmic_direction_t

enum dmic_direction_t

DMIC Direction

Enumerator
DMIC_DIRECTION_INPUT	DMIC input.
DMIC_DIRECTION_OUTPUT	DMIC output.

dmic_mode_t

enum dmic_mode_t

DMIC operation mode

Enumerator
DMIC_MODE_SLAVE	DMIC interface in slave mode.
DMIC_MODE_MASTER	DMIC interface in master mode.

dmic_delay_t

enum dmic_delay_t

DMIC set input delay

Enumerator
DMIC_DI_NO_DELAY	DMIC no input delay.
DMIC_DI_6NS_DELAY	DMIC 6ns input delay.
DMIC_DI_12NS_DELAY	DMIC 12ns input delay.
DMIC_DI_18NS_DELAY	DMIC 18ns input delay.

dmic_event_t

enum dmic_event_t

Events that can trigger a callback function

Enumerator
DMIC_EVENT_IDLE	Communication is idle.
DMIC_EVENT_TX_EMPTY	Transmit buffer is below FIFO trigger level.
DMIC_EVENT_RX_FULL	Receive buffer is above FIFO trigger level.

dmic_mute_t

enum dmic_mute_t

Mute audio samples.

Enumerator
DMIC_MUTE_OFF	Disable mute.
DMIC_MUTE_ON	Enable mute.

dmic_state_t

enum dmic_state_t

Possible status values returned by dmic_api_t::statusGet.

Enumerator
DMIC_STATE_IN_USE	DMIC is in use.
DMIC_STATE_STOPPED	DMIC is stopped.