Found an interesting formula for calculating Daylight Saving Time and thought I would share some code for those less experienced than myself. Hope it helps someone.
public class Program
{
private static bool timeUpdate = false;
public static void Main()
{
Microsoft.SPOT.Net.NetworkInformation.NetworkInterface NI = Microsoft.SPOT.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces()[0];
if (NI.IsDhcpEnabled == false)
{
Debug.Print("Static: \nIP Address = " + NI.IPAddress + " \nNet Mask = " + NI.SubnetMask + " \nGateway = " + NI.GatewayAddress);
}
while (true)
{
if (timeUpdate == false)
{
//myTime Update = new myTime();
//Update.NTPTime("time-a.nist.gov", -300);
setTime updateTime = new setTime(); // instantiate an instance of setTime class
Utility.SetLocalTime(updateTime.NTPTime("time-a.nist.gov")); //update time using setTime's NTPTime method
timeUpdate = true;
Debug.Print("Updated Time: " + DateTime.Now.ToString()); //displays updated time in VS2010 output window
}
}
}
}
public class setTime
{
DateTime networkDateTime;
public DateTime NTPTime(String TimeServer)
{
try
{
// Find endpoint for timeserver
EndPoint ep = new IPEndPoint(Dns.GetHostEntry(TimeServer).AddressList[0], 123);
// Connect to timeserver
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
s.Connect(ep);
// Make send/receive buffer
byte[] ntpData = new byte[48];
Array.Clear(ntpData, 0, 48);
// Set protocol version
ntpData[0] = 0x1B;
// Send Request
s.Send(ntpData);
// Receive Time
s.Receive(ntpData);
byte offsetTransmitTime = 40;
ulong intpart = 0;
ulong fractpart = 0;
for (int i = 0; i <= 3; i++)
intpart = (intpart << 8) | ntpData[offsetTransmitTime + i];
for (int i = 4; i <= 7; i++)
fractpart = (fractpart << 8) | ntpData[offsetTransmitTime + i];
ulong milliseconds = (intpart * 1000 + (fractpart * 1000) / 0x100000000L);
s.Close();
TimeSpan timeSpan = TimeSpan.FromTicks((long)milliseconds * TimeSpan.TicksPerMillisecond);
DateTime dateTime = new DateTime(1900, 1, 1);
dateTime += timeSpan;
int offset = getOffSet(dateTime); //sets UTC time
TimeService.SetTimeZoneOffset(offset);
TimeSpan offsetAmount = TimeZone.CurrentTimeZone.GetUtcOffset(dateTime);
networkDateTime = (dateTime + offsetAmount);
return networkDateTime;
}
catch
{
Debug.Print("Time update failed...");
return networkDateTime;
}
}
private int getOffSet(DateTime NTPServerTime)
{
//This method returns a UTC offset(in minutes) by calculating the correct day DST occurs and adjusting offset accordingly.
//This version only works in timezones with a negative initial offset(a.k.a North America .et al) Calculations are accurate to year 2099.
int offSetInMinutes = -300; // set for US central time(in minutes). Set for your timezone.
int year = NTPServerTime.Year;
double marchDay = 14 - (System.Math.Floor(1 + year * 5 / 4) % 7); //find day in March the DST occurs
int intMarchDay = (int)marchDay; //cast marchDay to int
double novDay = 7 - (System.Math.Floor(1 + year * 5 / 4) % 7); //find day in November the DST occurs
int intNovDay = (int)novDay; //cast novDay to int
Debug.Print("marchDay: " + intMarchDay.ToString());
Debug.Print("novDay: " + intNovDay.ToString());
DateTime marchChange = new DateTime(year, 3, intMarchDay, 2, 0, 0);
DateTime novChange = new DateTime(year, 11, intNovDay, 2, 0, 0);
if (NTPServerTime <= marchChange || NTPServerTime >= novChange)
{
offSetInMinutes -= 60; //Subtract and hour for DST change
//Debug.Print("OffSet: " + offSetInMinutes.ToString());
}
else
{
offSetInMinutes += 0;
}
return offSetInMinutes;
}
}
