wrong time occasionally

[gadjet]

Hi,
I'm using the library (great job by the way) with an ESP-12 and I'm publishing some data to MQTT server, including time, then shutting down for 2 min's (Deep sleep) then starting again.

sometimes the time returned is 00:00:12 ~(the seconds vary) mostly the time returned is correct.

Is there a minimum time for the server to respond, is the 00:00:12 time returned because the server has not responded in time?

Any thoughts?

[gerardwr]

I'm using the (great!) library on an ESP8266 too.

I also experience the problem that in some cases the NTP time returned is 00:00:xx. I guess this happens when the connection to the NTP server fails.

I checked the source of the library to look for a fail/success flag but did not find any :-(

Perhaps the update() function could return a boolean that indicates the validity of the NTP time?

[sandeepmistry]

Is there a minimum time for the server to respond, is the 00:00:12 time returned because the server has not responded in time?

The timeout is currently 1 second (10ms * 100 retry attempts). So, if the request or response gets "lost", getRawTime will return a value based on millis().

Perhaps the update() function could return a boolean that indicates the validity of the NTP time?

Another option is to have a hasUpdated API or something similar. @FWeinb what do you think?

[FWeinb]

I don't see a reason not to return a bool from update. But if the timeout was hit we should ensure that update() will do a forceUpdate() the next time it is called. We might want to implement a backoff strategy too.

[gerardwr]

As a workaround i use the value of getRawTime().

The sketch looks something like:

    timeClient.update();
    if (timeClient.getRawTime() > 1000 ){
      // seems that it is a valid NTPtime
      out="NTP time updated : ";
      Serial.println(out);
      // set Arduino/ESP time to local time
      setTime(timeClient.getRawTime());
    }
    else Serial.println("Update NTP time failed");

For the current time the value is something like: 1460479647
NTP time updated : 16:47:27 1460479647
If the value is low (I use 1000 as limit) getting the NTP time apparently failed, and I leave the local Arduino time unchanged. If the value is higher I use the value to set the local Arduino time.

As a rule I get a valid NTP time within a couple of minutes after reboot (retry every minute).

[sandeepmistry]

I don't see a reason not to return a bool from update

Ok, what do we want the behaviour to be for:

• update() call before update interval has passed? true?
• update() or forceUpdate() success: true
• update()or forceUpdate() failure: false

[FWeinb]

That is a good summary. Looks good. That should be useful to determine if the update succeed. We need to ensure that if forceUpdate() fails that update will call it again in the next run.

[sandeepmistry]

We need to ensure that if forceUpdate() fails that update will call it again in the next run.

Hmm, can't we make it rely on _lastUpdate containing the old value? Then update() will trigger forceUpdate() again.

This does not cover a mixed use of forceUpdate() failing followed by an immediate call to update() if the update interval hasn't passed. However, I think this is ok.

[FWeinb]

It looks like this isn't working correctly now, otherwise this issue should not be present in 2.0.0. But it would be great to find why this isn't currently working.

[blackketter]

Pull request #22 includes an updated() method for checking to see if the time has ever been updated.
Also, that patch makes updating non-blocking and may address the issue of wrong times being returned. Can you test?