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DMIC

Overview

The audio DMIC interface provides access to digital microphones.

Configuration Options

Related configuration options:

API Reference

group audio_dmic_interface

Abstraction for digital microphones.

Enums

enum dmic_state

DMIC driver states

Values:

DMIC_STATE_UNINIT
DMIC_STATE_INITIALIZED
DMIC_STATE_CONFIGURED
DMIC_STATE_ACTIVE
DMIC_STATE_PAUSED
enum dmic_trigger

DMIC driver trigger commands

Values:

DMIC_TRIGGER_STOP
DMIC_TRIGGER_START
DMIC_TRIGGER_PAUSE
DMIC_TRIGGER_RELEASE
DMIC_TRIGGER_RESET
enum pdm_lr

PDM Channels LEFT / RIGHT

Values:

PDM_CHAN_LEFT
PDM_CHAN_RIGHT

Functions

static u32_t dmic_build_channel_map(u8_t channel, u8_t pdm, enum pdm_lr lr)

Build the channel map to populate struct pdm_chan_cfg

Returns the map of PDM controller and LEFT/RIGHT channel shifted to the bit position corresponding to the input logical channel value

Return

Bit-map containing the PDM and L/R channel information

Parameters
  • channel: The logical channel number

  • pdm: The PDM hardware controller number

  • lr: LEFT/RIGHT channel within the chosen PDM hardware controller

static void dmic_parse_channel_map(u32_t channel_map_lo, u32_t channel_map_hi, u8_t channel, u8_t *pdm, enum pdm_lr *lr)

Helper function to parse the channel map in pdm_chan_cfg

Returns the PDM controller and LEFT/RIGHT channel corresponding to the channel map and the logical channel provided as input

Return

none

Parameters
  • channel_map_lo: Lower order/significant bits of the channel map

  • channel_map_hi: Higher order/significant bits of the channel map

  • channel: The logical channel number

  • pdm: Pointer to the PDM hardware controller number

  • lr: Pointer to the LEFT/RIGHT channel within the PDM controller

static u32_t dmic_build_clk_skew_map(u8_t pdm, u8_t skew)

Build a bit map of clock skew values for each PDM channel

Returns the bit-map of clock skew value shifted to the bit position corresponding to the input PDM controller value

Return

Bit-map containing the clock skew information

Parameters
  • pdm: The PDM hardware controller number

  • skew: The skew to apply for the clock output from the PDM controller

static int dmic_configure(struct device *dev, struct dmic_cfg *cfg)

Configure the DMIC driver and controller(s)

Configures the DMIC driver device according to the number of channels, channel mapping, PDM I/O configuration, PCM stream configuration, etc.

Return

0 on success, a negative error code on failure

Parameters
  • dev: Pointer to the device structure for DMIC driver instance

  • cfg: Pointer to the structure containing the DMIC configuration

static int dmic_trigger(struct device *dev, enum dmic_trigger cmd)

Send a command to the DMIC driver

Sends a command to the driver to perform a specific action

Return

0 on success, a negative error code on failure

Parameters
  • dev: Pointer to the device structure for DMIC driver instance

  • cmd: The command to be sent to the driver instance

static int dmic_read(struct device *dev, u8_t stream, void **buffer, size_t *size, s32_t timeout)

Read received decimated PCM data stream

Optionally waits for audio to be received and provides the received audio buffer from the requested stream

Return

0 on success, a negative error code on failure

Parameters
  • dev: Pointer to the device structure for DMIC driver instance

  • stream: Stream identifier

  • buffer: Pointer to the received buffer address

  • size: Pointer to the received buffer size

  • timeout: Timeout in milliseconds to wait in case audio is not yet received, or SYS_FOREVER_MS

struct pdm_io_cfg
#include <dmic.h>

PDM Input/Output signal configuration

struct pcm_stream_cfg
#include <dmic.h>

Configuration of the PCM streams to be output by the PDM hardware

struct pdm_chan_cfg
#include <dmic.h>

Mapping/ordering of the PDM channels to logical PCM output channel

struct dmic_cfg
#include <dmic.h>

Input configuration structure for the DMIC configuration API