samples: drivers: Add simple application showing how to use DMIC API

# SPDX-License-Identifier: Apache-2.0

cmake_minimum_required(VERSION 3.13.1)

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

project(dmic)

target_sources(app PRIVATE src/main.c)

.. _dmic_sample:

DMIC Sample

###########

Overview

********

This is a very simple application intended to show how to use the Audio DMIC

API and also to be an aid in developing drivers to implement this API.

It performs two PDM transfers with different configurations (using one channel

and two channels) but does not in any way process the received audio data.

Requirements

************

The device to be used by the sample is specified by defining a devicetree node

label named ``dmic_dev``.

The sample has been tested on :ref:`nrf52840dk_nrf52840` (nrf52840dk_nrf52840)

and :ref:`nrf5340dk_nrf5340` (nrf5340dk_nrf5340_cpuapp), and provides overlay

files for both of these boards.

Building and Running

********************

The code can be found in :zephyr_file:`samples/drivers/audio/dmic`.

To build and flash the application:

.. zephyr-app-commands::

   :zephyr-app: samples/drivers/audio/dmic

   :board: nrf52840dk_nrf52840

   :goals: build flash

   :compact:

/*

 * Copyright (c) 2021 Nordic Semiconductor ASA

 *

 * SPDX-License-Identifier: Apache-2.0

 */

dmic_dev: &pdm0 {

	status = "okay";

	clk-pin = <30>;

	din-pin = <31>;

	clock-source = "PCLK32M_HFXO";

};

/*

 * Copyright (c) 2021 Nordic Semiconductor ASA

 *

 * SPDX-License-Identifier: Apache-2.0

 */

&clock {

	hfclkaudio-frequency = <12288000>;

};

dmic_dev: &pdm0 {

	status = "okay";

	clk-pin = <25>;

	din-pin = <26>;

	clock-source = "ACLK";

};

CONFIG_AUDIO=y

CONFIG_AUDIO_DMIC=y

CONFIG_LOG=y