N3WWeather.cs

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

namespace N3WWeather
{
    public class Program
    {
        // Visit Weather Underground to get a free API key: http://www.wunderground.com/weather/api/
        private const string WeatherUndergroundAPIKey = "YOUR_API_KEY_HERE";

        // Set the delay between weather updates
        private static int _weatherUpdateDelayMinutes = 5;
        // Temperature scale to display
        private static TemperatureScale _displayScale = TemperatureScale.Fahrenheit;

        public static void Main()
        {
            // Initialize Seven Segment Display
            var display = new SevenSegmentDisplay();
            display.SetValue("....");

            // Wait for network connection and DHCP
            while (IPAddress.GetDefaultLocalAddress() == IPAddress.Any)
                Thread.Sleep(10);

            // Set up our display unit
            Digit unit = Digit.Blank;
            switch (_displayScale)
            {
                case TemperatureScale.Fahrenheit:
                    unit = Digit.F;
                    break;
                case TemperatureScale.Celsius:
                    unit = Digit.C;
                    break;
            }

            // Continuously update weather
            while (true)
            {
                try
                {
                    double temperature = GetWeather();
                    display.SetTemperatureDisplay(temperature, unit);
                }
                catch { }
                Thread.Sleep(1000 * 60 * _weatherUpdateDelayMinutes);
            }
        }

        /// <summary>
        /// Retrieves the current temperature from Weather Underground.
        /// </summary>
        /// <param name="query">Weather query to perform, e.g., "CA/San_Francisco" or a US zipcode. Use null to specify automatic IP address-based location.</param>
        private static double GetWeather(string query = null)
        {
            // If no query was specified, automatically determine the current location based on the connecting IP.
            if (query == null)
                query = "autoip";

            // Set up the request URI
            string uri = "http://api.wunderground.com/api/" + WeatherUndergroundAPIKey + "/conditions/q/" + query + ".xml";

            // Set up search values
            string searchStart, searchEnd;
            switch (_displayScale)
            {
                case TemperatureScale.Fahrenheit:
                    searchStart = "<temp_f>";
                    searchEnd = "</temp_f>";
                    break;

                case TemperatureScale.Celsius:
                    searchStart = "<temp_c>";
                    searchEnd = "</temp_c>";
                    break;

                default:
                    throw new Exception();
            }

            // Make the request
            using (var request = (HttpWebRequest)WebRequest.Create(uri))
            using (var response = request.GetResponse())
            using (var stream = response.GetResponseStream())
            using (var reader = new StreamReader(stream))
            {
                string line;
                int indexStart, indexEnd;

                do
                {
                    // Read each line, looking for our search values
                    line = reader.ReadLine();
                    indexStart = line.IndexOf(searchStart);
                    if (indexStart >= 0)
                    {
                        indexStart += searchStart.Length;
                        indexEnd = line.IndexOf(searchEnd, indexStart);
                        return double.Parse(line.Substring(indexStart, indexEnd - indexStart));
                    }

                } while (!reader.EndOfStream);
            }

            // Couldn't find a result
            throw new Exception();
        }
    }

    enum TemperatureScale
    {
        Fahrenheit,
        Celsius,
    }
}