samples: sensor: added sample app for INA219

This adds an example application for the TI INA219 Zero-Drift,
Bidirectional Current/Power Monitor with I2C Interface

Signed-off-by: Leonard Pollak <leonardp@tr-host.de>

samples/sensor/ina219/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(ina219)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/sensor/ina219/README.rst

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+.. _ina219:
+
+INA219 Bidirectional Power/Current Monitor
+##########################################
+
+Overview
+********
+
+This sample application measures shunt voltage, bus voltage, power and current
+every 2 seconds and prints them to console.
+The calibration/configuration parameters can be set in the devicetree file.
+
+References
+**********
+
+ - `INA219 sensor <https://www.ti.com/product/INA219>`_
+
+Wiring
+******
+
+The supply voltage of the INA219 can be in the 3V to 5.5V range.
+The common mode voltage of the measured bus can be in the 0V to 26V range.
+
+Building and Running
+********************
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/ina219
+   :board: blackpill_f411ce
+   :goals: build flash
+
+Sample Output
+=============
+When monitoring a 3.3 V bus with a 0.1 Ohm shunt restistor
+you should get a similar output as below, repeated every 2 seconds:
+
+.. code-block:: console
+
+        Shunt: 0.001570 [V] -- Bus: 3.224000 [V] -- Power: 0.504000 [W] -- Current: 0.157000 [A]
+
+
+A negative sign indicates current flowing in reverse direction:
+
+.. code-block:: console
+
+        Shunt: -0.001560 [V] -- Bus: 3.224000 [V] -- Power: 0.502000 [W] -- Current: -0.156000 [A]

samples/sensor/ina219/boards/blackpill_f411ce.overlay

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+/*
+ * Copyright (c) 2021 Leonard Pollak
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&i2c1 {
+	status = "okay";
+	compatible = "st,stm32-i2c-v1";
+	clock-frequency = <I2C_BITRATE_FAST>;
+	label = "I2C_0";
+
+	ina219@40 {
+		status = "okay";
+		compatible = "ti,ina219";
+		reg = <0x40>;
+		label = "INA219";
+		brng = <0>;
+		pg = <0>;
+		sadc = <13>;
+		badc = <13>;
+		shunt-milliohm = <100>;
+		lsb-microamp = <10>;
+	};
+};

samples/sensor/ina219/prj.conf

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+CONFIG_STDOUT_CONSOLE=y
+CONFIG_CBPRINTF_FP_SUPPORT=y
+CONFIG_I2C=y
+CONFIG_SENSOR=y
+CONFIG_INA219=y

samples/sensor/ina219/sample.yaml

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+#
+# Copyright (c) 2021 Leonard Pollak
+#
+# SPDX-License-Identifier: Apache-2.0
+
+
+sample:
+  name: TI INA219 power/current monitor
+  description: Demonstration of the INA219 I2C power/current monitor
+tests:
+  sample.drivers.ina219:
+    build_only: true
+    platform_allow: blackpill_f411ce
+    tags: sensors

samples/sensor/ina219/src/main.c

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+/*
+ * Copyright (c) 2021 Leonard Pollak
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <stdio.h>
+#include <drivers/sensor.h>
+
+
+void main(void)
+{
+	const struct device *ina = DEVICE_DT_GET_ONE(ti_ina219);
+	struct sensor_value v_bus, power, current;
+	int rc;
+
+	if (!device_is_ready(ina)) {
+		printf("Device %s is not ready.\n", ina->name);
+		return;
+	}
+
+	while (true) {
+		rc = sensor_sample_fetch(ina);
+		if (rc) {
+			printf("Could not fetch sensor data.\n");
+			return;
+		}
+
+		sensor_channel_get(ina, SENSOR_CHAN_VOLTAGE, &v_bus);
+		sensor_channel_get(ina, SENSOR_CHAN_POWER, &power);
+		sensor_channel_get(ina, SENSOR_CHAN_CURRENT, &current);
+
+		printf("Bus: %f [V] -- "
+			"Power: %f [W] -- "
+			"Current: %f [A]\n",
+		       sensor_value_to_double(&v_bus),
+		       sensor_value_to_double(&power),
+		       sensor_value_to_double(&current));
+		k_sleep(K_MSEC(2000));
+	}
+}