This library makes it easy to fetch a timestamp from an NTP timeserver. In order to use this library you will need the UDP libraries from: http://bitbucket.org/bjoern/arduino_osc/ You will also need to modify the library to allow enough space in the buffers for the NTP packets. Open up UdpBytewise.h and change these lines: #define UDP_TX_PACKET_MAX_SIZE 32 #define UDP_RX_PACKET_MAX_SIZE 32 to this: #define UDP_TX_PACKET_MAX_SIZE 64 #define UDP_RX_PACKET_MAX_SIZE 64