samples: sensor: new sample to demonstrate the Vbat monitoring

# SPDX-License-Identifier: Apache-2.0

cmake_minimum_required(VERSION 3.20.0)

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

project(stm32_vbat_sensor)

FILE(GLOB app_sources src/*.c)

target_sources(app PRIVATE ${app_sources})

.. _stm32_vbat_sensor:

STM32 VBat Sensor

#################

Overview

********

This sample reads the Vbat from the STM32 Internal

Sensor and displays the results.

Building and Running

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

In order to run this sample, make sure to enable ``stm32_vbat`` node in your

board DT file or with a board overlay in the samples/sensor/stm32_temp_sensor/boards :

.. code-block:: dts

    stm32_vbat: stm32vbat {

        compatible = "st,stm32-vbat";

        label = "VBAT";

        io-channels = <&adc1 14>;

        ratio = <3>;

        status = "okay";

    };

Enable the corresponding ADC, with the correct vref value (in mV)

.. code-block:: dts

    &adc1 {

	vref-mv = <3000>;

	status = "okay";

    };

.. zephyr-app-commands::

   :zephyr-app: samples/sensor/stm32_vbat_sensor

   :board: nucleo_g071rb

   :goals: build

   :compact:

Sample Output

=============

.. code-block:: console

Current Vbat voltage: 3.04 V

/*

 * Copyright (c) 2022 STMicroelectronics

 *

 * SPDX-License-Identifier: Apache-2.0

 *

 * Application overlay for creating vbat sensor device instance

 */

/ {

	stm-vbat {

		compatible = "st,stm32-vbat";

		ratio = <3>;

		io-channels = <&adc1 14>;

		status = "okay";

		label = "VBAT";

	};

};

/*

 * Copyright (c) 2022 STMicroelectronics

 *

 * SPDX-License-Identifier: Apache-2.0

 *

 * Application overlay for creating vbat sensor device instance

 */

/ {

	stm-vbat {

		compatible = "st,stm32-vbat";

		ratio = <3>;

		io-channels = <&adc1 18>;

		status = "okay";

		label = "VBAT";

	};

};

&adc1 {

	has-vbat-channel;

	vref-mv = <3300>;

};

CONFIG_SENSOR=y

CONFIG_ADC=y

CONFIG_STM32_VBAT=y

CONFIG_PRINTK=y

CONFIG_CBPRINTF_FP_SUPPORT=y