The sntp client is implemented as a thread which listens for NTP
broadcasts and IPv6 multicasts, and optionally sends SNTP unicast
requests to specific NTP servers. This thread may be automatically
started by the system if it receives a list of (S)NTP servers from the
DHCP server and unicast mode is enabled. Otherwise it must be started
by the user application. The header file
cyg/sntp/sntp.h declares the function to be
called. The thread is then started by calling the function:
void cyg_sntp_start(void);
It is safe to call this function multiple times. Once started, the
thread will run forever.