Add new functionality to Bme680 binding (#482)

* Add driver

* Add samples

* Add Readme

* Add missing reference

* Remove unreachable code, remove TODOs

* Update I2C address in samples

* Modify csproj to only compile default sample

* Bit manipulation and documentation updates, small bugfix

* sample update

* remove outdated binding

* Fix temperature compensating formula

* Add remaining registers

* Add data masks

* Add HeaterProfile enum

* Add status properties + current heater profile

* Update csproj

* Add filtering mode for Bme680

* Add remaining calibration registers

* Simplify methods, add setFilterMode

* Add HeaterProfileConfig class

* Add gas measurement functionality

* Add gas measurement functionality for real...

* Use methods where appropriate, update sample

* Update Bme280 sample

* Add default configuration

* Reset device upon initial config, update samples

* Add license notice

* Set defaults through constructor, update sample

* Cache values instead of repeated reading from device

* Improve caching behavior, update samples

* Update Bmp280 sample

* Add missing headers

* fix typo

* Add missing xml documentation, argument check

* Update sample

* Add missing caching of values

* move fields to top of file

* Rename CurrentHeaterProfile

* Update sample

* fix CI

* Use stackalloc, make appropriate variables static

* Update read methods to work synchronous

* Remove async signature from samples

* Update methods to burst read registers if possible

* fix xml documentation

* Change Read methods to TryRead

* Align behavior with Bmx280 bindings

* fix method call

* update xml documentation

* Update doc, remove Todo, adhere to naming guideline

* Update README.md

* Add missing xml docs

* Load calibration and default config in base

* Remove redundant import

* minor update to readme

src/devices/Bmxx80/Bme280.cs

@@ -2,18 +2,17 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Device.I2c;
-using System.Threading.Tasks;
 using Iot.Device.Bmxx80.CalibrationData;
-using Iot.Device.Bmxx80.PowerMode;
 using Iot.Device.Bmxx80.Register;
 
 namespace Iot.Device.Bmxx80
 {
     /// <summary>
     /// Represents a BME280 temperature, barometric pressure and humidity sensor.
     /// </summary>
-    public class Bme280 : Bmx280Base
+    public sealed class Bme280 : Bmx280Base
     {
         /// <summary>
         /// The expected chip ID of the BME280.
@@ -23,7 +22,9 @@ public class Bme280 : Bmx280Base
         /// <summary>
         /// Calibration data for the <see cref="Bme680"/>.
         /// </summary>
-        private readonly Bme280CalibrationData _bme280Calibration;
+        private Bme280CalibrationData _bme280Calibration;
+
+        private Sampling _humiditySampling;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="Bme280"/> class.
@@ -32,62 +33,79 @@ public class Bme280 : Bmx280Base
         public Bme280(I2cDevice i2cDevice)
             : base(DeviceId, i2cDevice)
         {
-            var bme280CalibrationData = new Bme280CalibrationData();
-            bme280CalibrationData.ReadFromDevice(this);
-            _bme280Calibration = bme280CalibrationData;
-            _calibrationData = bme280CalibrationData;
-
+            _bme280Calibration = (Bme280CalibrationData)_calibrationData;
             _communicationProtocol = CommunicationProtocol.I2c;
         }
 
         /// <summary>
-        /// Get the current sample rate for humidity measurements.
+        /// Gets or sets the humidity sampling.
         /// </summary>
-        /// <returns>The humidity <see cref="Sampling"/>.</returns>
-        public Sampling ReadHumiditySampling()
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the <see cref="Sampling"/> is set to an undefined mode.</exception>
+        public Sampling HumiditySampling
         {
-            byte status = Read8BitsFromRegister((byte)Bme280Register.CTRL_HUM);
-            status = (byte)(status & 0b_0000_0111);
-            return ByteToSampling(status);
+            get => _humiditySampling;
+            set
+            {
+                if (!Enum.IsDefined(typeof(Sampling), value))
+                    throw new ArgumentOutOfRangeException();
+
+                byte status = Read8BitsFromRegister((byte)Bme280Register.CTRL_HUM);
+                status = (byte)(status & 0b_1111_1000);
+                status = (byte)(status | (byte)value);
+
+                Span<byte> command = stackalloc[] {(byte)Bme280Register.CTRL_HUM, status};
+                _i2cDevice.Write(command);
+
+                // Changes to the above register only become effective after a write operation to "CTRL_MEAS".
+                byte measureState = Read8BitsFromRegister((byte)Bmx280Register.CTRL_MEAS);
+
+                command = stackalloc[] {(byte)Bmx280Register.CTRL_MEAS, measureState};
+                _i2cDevice.Write(command);
+                _humiditySampling = value;
+            }
         }
 
         /// <summary>
-        /// Sets the humidity sampling to the given value.
+        /// Reads the humidity. A return value indicates whether the reading succeeded.
         /// </summary>
-        /// <param name="sampling">The <see cref="Sampling"/> to set.</param>
-        public void SetHumiditySampling(Sampling sampling)
+        /// <param name="humidity">
+        /// Contains the measured humidity as %rH if the <see cref="HumiditySampling"/> was not set to <see cref="Sampling.Skipped"/>.
+        /// Contains <see cref="double.NaN"/> otherwise.
+        /// </param>
+        /// <returns><code>true</code> if measurement was not skipped, otherwise <code>false</code>.</returns>
+        public bool TryReadHumidity(out double humidity)
         {
-            byte status = Read8BitsFromRegister((byte)Bme280Register.CTRL_HUM);
-            status = (byte)(status & 0b_1111_1000);
-            status = (byte)(status | (byte)sampling);
-            _i2cDevice.Write(new[] { (byte)Bme280Register.CTRL_HUM, status });
-
-            // Changes to the above register only become effective after a write operation to "CTRL_MEAS".
-            byte measureState = Read8BitsFromRegister((byte)Bmx280Register.CTRL_MEAS);
-            _i2cDevice.Write(new[] { (byte)Bmx280Register.CTRL_MEAS, measureState });
+            if (HumiditySampling == Sampling.Skipped)
+            {
+                humidity = double.NaN;
+                return false;
+            }
+
+            // Read the temperature first to load the t_fine value for compensation.
+            TryReadTemperature(out _);
+
+            var hum = Read16BitsFromRegister((byte)Bme280Register.HUMIDDATA, Endianness.BigEndian);
+
+            humidity = CompensateHumidity(hum);
+            return true;
         }
 
         /// <summary>
-        /// Reads the Humidity from the sensor as %rH.
+        /// Gets the required time in ms to perform a measurement with the current sampling modes.
         /// </summary>
-        /// <returns>Returns a percentage from 0 to 100.</returns>
-        public async Task<double> ReadHumidityAsync()
+        /// <returns>The time it takes for the chip to read data in milliseconds rounded up.</returns>
+        public override int GetMeasurementDuration()
         {
-            if (ReadPowerMode() == Bmx280PowerMode.Forced)
-            {
-                await Task.Delay(GetMeasurementTimeForForcedMode(ReadHumiditySampling()));
-            }
-
-            // Read the temperature first to load the t_fine value for compensation.
-            await ReadTemperatureAsync();
-
-            byte msb = Read8BitsFromRegister((byte)Bme280Register.HUMIDDATA_MSB);
-            byte lsb = Read8BitsFromRegister((byte)Bme280Register.HUMIDDATA_LSB);
-
-            // Combine the values into a 32-bit integer.
-            int t = (msb << 8) | lsb;
+            return s_osToMeasCycles[(int)PressureSampling] + s_osToMeasCycles[(int)TemperatureSampling] + s_osToMeasCycles[(int)HumiditySampling];
+        }
 
-            return CompensateHumidity(t);
+        /// <summary>
+        /// Sets the default configuration for the sensor.
+        /// </summary>
+        protected override void SetDefaultConfiguration()
+        {
+            base.SetDefaultConfiguration();
+            HumiditySampling = Sampling.UltraLowPower;
         }
 
         /// <summary>