sntp_get_time

#include <rtl.h>

BOOL sntp_get_time (
    U8*   ipadr,             /* IP address of NTP/SNTP server. */
    void (*cbfunc)(          /* Function to call when TCPnet receives NTP message. */
          U32 utc_time) );   /* Received utc time (seconds elapsed since 1.1.1970) */

The sntp_get_time function, in unicast mode, sends a get time request to NTP server. Parameter ipadr specifies the IP address of NTP server, where the request is destined to.

The sntp_get_time function, in broadcast mode, opens UDP socket for receiving broadcasted NTP messages. You can use broadcast mode, if you have a broadcasting NTP server in your local network. Parameter ipadr specifies the IP address of local NTP server. The NTP messages that come from specified NTP server are accepted, the messages that come from different NTP server are ignored. If IP address, specified in ipadr is 0.0.0.0, NTP messages from any NTP server are accepted.

If the IP address of NTP server is not specified (parameter ipadr is NULL), the IP address of NTP Server configured in Net_Config.c is used instead.

The argument cbfunc points to a function that the SNTP client running on TCPnet calls, when NTP message is received from the server. The cbfunc is an event callback function that uses the utc_time argument of the cbfunc to signal the time. The time is specified in utc (unix time in seconds, elapsed since 1.1.1970). The value of 0 is reserved to report an error.

The sntp_get_time function is in the RL-TCPnet library. The prototype is defined in rtl.h.

The sntp_get_time function returns __TRUE when the SNTP message has been sent successfully in unicast mode, or UDP socket successfully opened in broadcast mode. On error, this function returns __FALSE.

static void time_cback (U32 time);

void get_time (void) {
  U8 ntp_server[4] = {217,79,179,106};

  if (sntp_get_time (&ntp_server[0], time_cback) == __TRUE) {
    printf ("SNTP request sent.\n");
  }
  else {
    printf ("Failed, SNTP not ready or bad parameters.\n");
  }
}

static void time_cback (U32 time) {
  if (time == 0) {
    printf ("Error, server not responding or bad response.\n");
  }
  else {
    printf ("%d seconds elapsed since 1.1.1970\n", time);
  }
}