EasyNTPClient

Arduino library to read time from Network Time Protocol (NTP) servers.

 

Features

• Handles all heavy lifting involved with managing connections to and parsing time from an NTP server.
• As easy as providing a UDP object to the constructor during initialization.
• Works on Arduino, ESP8266, and ESP32.
• Configurable NTP server pool, time offset, and update interval.
• Stale time preservation: returns the last known time when a resync fails.

 

Examples

1. NodeMCU
   Using EasyNTPClient on a NodeMCU (ESP8266).

2. ArduinoEspWifiShield
   Using EasyNTPClient on an Arduino UNO with an ESP-01 (ESP8266) WiFi module.

3. TestNTPClient
   Full test suite covering all features. Runs on ESP8266, ESP32, and Uno+ESP-01.

 

Reference

Class EasyNTPClient

1. Initialization

1. No frills

   EasyNTPClient(UDP &udp)
   
   Parameters:
       udp: Reference to a UDP object.
   Returns:
       EasyNTPClient object.

2. Custom server pool

   EasyNTPClient(UDP& udp, const char* serverPool)
   
   Parameters:
       udp: Reference to a UDP object.
       serverPool: NTP server pool domain name. Default = "pool.ntp.org"
   Returns:
       EasyNTPClient object.

3. Time offset

   EasyNTPClient(UDP& udp, const char* serverPool, int offset)
   
   Parameters:
       udp: Reference to a UDP object.
       serverPool: NTP server pool domain name. Default = "pool.ntp.org"
       offset: Difference from UTC in seconds. Default = 0
   Returns:
       EasyNTPClient object.

4. Time offset and update interval

   EasyNTPClient(UDP& udp, const char* serverPool, int offset, uint32_t updateIntervalSecs)
   
   Parameters:
       udp: Reference to a UDP object.
       serverPool: NTP server pool domain name. Default = "pool.ntp.org"
       offset: Difference from UTC in seconds. Default = 0
       updateIntervalSecs: How often to resync with the NTP server, in seconds. Default = 60
   Returns:
       EasyNTPClient object.

2. Methods

1. Get Unix time

   unsigned long getUnixTime()
   
   Returns:
       Current time as a Unix timestamp (seconds since 1970-01-01 00:00:00 UTC),
       adjusted by the configured time offset. Resyncs with the NTP server when
       the update interval has elapsed. Returns the last known time if resync fails.

2. Get time offset

   int getTimeOffset()
   
   Returns:
       Current time offset from UTC in seconds.

3. Set time offset

   void setTimeOffset(int offset)
   
   Parameters:
       offset: Difference from UTC in seconds.

4. Get NTP server

   const char* getNTPServer()
   
   Returns:
       The current NTP server pool domain name.

5. Set NTP server

   void setNTPServer(const char* serverPool)
   
   Parameters:
       serverPool: NTP server pool domain name.

6. Get update interval

   uint32_t getUpdateInterval()
   
   Returns:
       How often the client resyncs with the NTP server, in seconds.

7. Set update interval

   void setUpdateInterval(uint32_t seconds)
   
   Parameters:
       seconds: Resync interval in seconds.

8. Check if last sync succeeded

   bool wasUpdated()
   
   Returns:
       true if the most recent NTP resync attempt succeeded,
       false if it failed or no resync has been attempted yet.