View source for Microduino ENC Network (12)——Use NTP to get Internet time

{{Language | Microduino ENC网络（十二）————用NTP获取Internet时间}}
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==Objective==
Today’s tutorial is about getting an accurate time via Internet, using the NTP (Network Time Protocol) service.

==Equipment==
*'''[[Microduino-Core]]'''
*'''[[Microduino-FT232R]]'''
*'''[[Microduino-ENC28J60]]'''
*'''[[Microduino-RJ45]]'''

*Other equipment
**USB cable

==NTP==

NTP is a client-server protocol at application layer; it uses UDP port 123 as transport protocol.

If you send a request to a NTP server, you receive in its response a 64bit value (timestamp) made by:

*the first 32bits represent the number of seconds since 01/01/1900;
*the last 32bits are the fraction of the actual second
[[File:NTP.jpg|600px|center|thumb]]


==Schematic==
*Microduino-ENC28J60
*Microduino-RJ45
*Microduino-Core
*Microduino-FT232R
Stack all modules and then connect the ethernet cable, as follows:

[[File:MicroduinoENCShow.jpg|600px|center|thumb]]

==Program==

https://github.com/Microduino/Microduino_Tutorials/tree/master/Microduino_ENC/ENCnetworktwelve

==Debug==
Step 1: Download the EtherCard library and copy to your libraries fold of IDE, then restart IDE.
https://github.com/jcw/ethercard

Step 2: Explain the program:
Many NTP servers are available on Internet: in the United States for example the NIST (National Institute of Standards and Technology) runs an entire network of severs. I live in Italy, so I chose as time server for this example the one run by the INRiM (Istituto Nazionale di Ricerca Metereologica):
    static byte ntpServer[] = {193,204,114,232};

The EtherCard library has two methods for NTP queries:
*ntpRequest(ntpServer, srcPort), sends a request to the specificed server;
*ntpProcessAnswer(&timeStamp, srcPort), gets the response and extracts the timestamp (only the first 32bits).

The srcPort parameter is used to find, among the many packets your Ethernet shield receives, the one that contains NTP server’s response: you can choose its value but it has to be the same both in the Request and in the ProcessAnswer.
Got the timestamp value, you have to convert it in date-time format. The method is the following:

*count the number of complete years contained in the timestamp;
*then find out how many complete months are in the rest of the timestamp;
*do the same for days, hours, minutes;
*the final rest is the number of seconds.

Just a few complications:

Years could be leap years: for those you have to consider 366*86500 seconds instead of 365*86500. To check if actual year is a leap one, you can use the following method:

    boolean isLeapYear(unsigned int year) {
      return (year % 4 == 0 &amp;&amp; (year % 100 != 0 || year % 400 == 0));
    }

The number of days in a month is variable: the value if saved in an array:

    static int days_in_month[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

If we're in a leap year, February has 29 days:

    if(isLeapYear(year) &amp;&amp; month == 1) seconds = SECONDS_IN_DAY * 29;

Finally, the timestamp value is referred to GMT, if you live in a different time zone, you have to adjust its value:

    #define TIME_ZONE               +1
    [...]
    printDate(timeStamp + 3600 * TIME_ZONE);

Step 3: Download the code and compile it.

Step 4: Open the serial to check the time.

==Result==

Serial port will display the time: 

[[File:NTPShowTime.jpg|600px|center|thumb]]

==Extension==
In order to observe the time easily, you can use the OLED to display the time.
[[File:MicroduinoENCTimeShow1.jpg|600px|center|thumb]]
[[File:MicroduinoENCTimeShow2.jpg|600px|center|thumb]]

==Video==


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