Netduino 3 Wi-Fi OneWire temperature sensor sent over MQTT

Program.cs

using System;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using System.Threading;
using System.IO;
using System.Net;
using SecretLabs.NETMF.Hardware.Netduino;
using Microsoft.SPOT.Net.NetworkInformation;

using uPLibrary.Networking.M2Mqtt;
using uPLibrary.Networking.M2Mqtt.Utility;
using MqttTrace = uPLibrary.Networking.M2Mqtt.Utility.Trace;

namespace NetduinoBlink
{
	public class Program
	{
		const string MqttUsername = "...";
		const string MqttPassword = "...";
		const string MqttTopic = "home/room/temperature";
		const string MqttIP = "192.168.x.x";

		static readonly byte[] SensorSerialNumber = new byte[8];
		static readonly byte[] MatchRomCommand = new byte[9];

		public static void Main()
		{
			Debug.Print ("Application starting...");
			var port = new OutputPort (Pins.GPIO_PIN_D7, false);
			var oneWire = new OneWire (port);
			var utf8Encoding = System.Text.Encoding.UTF8;

			if (!EnsureConnectedToNetwork ()) {
				Debug.Print ("Couldn't connect to network, bye.");
				return;
			}

			MqttTrace.TraceLevel = TraceLevel.Error | TraceLevel.Frame | TraceLevel.Queuing | TraceLevel.Information | TraceLevel.Verbose | TraceLevel.Warning;
			MqttTrace.TraceListener = (format, args) => Debug.Print (format);
			MqttClient client = null;
			try {
				client = new MqttClient (MqttIP, 8887, false, null, null, MqttSslProtocols.None);
				if (client.Connect ("netduino", MqttUsername, MqttPassword) != 0) {
					Debug.Print ("Couldn't connect to MQTT broker");
					return;
				}
			} catch (Exception ex) {
				Debug.Print ("Error while connecting to MQTT");
				Debug.Print (ex.ToString ());
				return;
			}
			Debug.Print ("MQTT connected");

			while (true) {
				try {
					var temp = ReadTemperature (oneWire);
					Debug.Print ("Current temperature is in C: " + temp);

					try {
						var shortTemp = temp.ToString ("F2");
						client.Publish (MqttTopic, utf8Encoding.GetBytes (shortTemp));
					} catch (Exception e) {
						Debug.Print ("Couldn't send temp update to MQTT");
						Debug.Print (e.ToString ());
					}
				} catch (Exception e) {
					Debug.Print ("A random exception happened");
					Debug.Print (e.ToString ());
					break;
				} finally {
					oneWire.Release ();
				}

				Thread.Sleep (20000);
			}

			if (client.IsConnected)
				client.Disconnect ();
		}

		static float ReadTemperature (OneWire oneWire)
		{
			try {
				oneWire.AcquireEx ();
				var firstDevice = oneWire.FindFirstDevice (performResetBeforeSearch: true,
				                                           searchWithAlarmCommand: false);
				Debug.Print ("First device id: " + firstDevice);
				oneWire.SerialNum (SensorSerialNumber, true);
				Array.Copy (SensorSerialNumber, 0, MatchRomCommand, 1, 8);
				PrintSerial (SensorSerialNumber);

				oneWire.TouchReset ();
				oneWire.WriteByte (0xCC /* SKIP ROM */);
				oneWire.WriteByte (0x44 /* ConvertT */);
				Thread.Sleep (750);

				oneWire.TouchReset ();
				MatchRomCommand[0] = 0x55 /* MATCH ROM */;
				for (int j = 0; j < MatchRomCommand.Length; j++)
					oneWire.WriteByte (MatchRomCommand[j]);
				oneWire.WriteByte (0xBE /* Read Scratchpad */);
				var tempLo = (byte)oneWire.ReadByte ();
				var tempHi = (byte)oneWire.ReadByte ();

				var temp = ConvertTemperature (tempLo, tempHi);

				return temp;
			} finally {
				oneWire.Release ();
			}
		}

		static float ConvertTemperature (byte tempLo, byte tempHi)
		{
			return ((short)((tempHi << 8) | tempLo)) / 16F;
		}

		static void PrintSerial (byte[] serial)
		{
			string output = "{";
			for (int i = 0; i < serial.Length; i++)
				output += serial[i].ToString ();
			output += "}";
			Debug.Print (output);
		}

		static bool EnsureConnectedToNetwork ()
		{
			var interfaces = NetworkInterface.GetAllNetworkInterfaces ();
			Debug.Print ("Found interface count: " + interfaces.Length);

			if (interfaces.Length == 0)
				return false;

			var iface = interfaces[0];
			if (HasDefaultIp (iface)) {
				if (!iface.IsDhcpEnabled) {
					Debug.Print ("No IP and no DHCP");
					return false;
				}

				Debug.Print ("Trying to get an IP address");
				for (int tries = 0; tries < 100; tries++) {
					Thread.Sleep (100);
					if (!HasDefaultIp (iface))
						break;
				}
				if (HasDefaultIp (iface)) {
					Debug.Print ("Still no IP");
					return false;
				}
			}

			Debug.Print ("Got an IP: " + iface.IPAddress);

			return true;
		}

		static bool HasDefaultIp (NetworkInterface iface) => string.Equals (iface.IPAddress, "0.0.0.0");
	}
}