ESP8266 - how to detect lack of internet when downloading NTP time?

Hello
While testing the download of NTP time through the ESP8266 module, I noticed that in the absence of Internet, when trying to connect, the program will stop ( this is how I have constructed the reception program - the program "turns" in the loop To .... Loop until ).
At first, I was thinking to create a second condition triggered by a Timer flag, but maybe it would be possible e.g. by connecting to a known website ( e.g. google.pl - 216.58.209.32 ).

That is to say:

"listen" for the text "Linked", admittedly if there is no internet the program will also hang and an additional condition is needed.

Maybe one of the Colleagues has coped differently and could give guidance ?

To test your internet connection, you can use the AT+PING command by sending a ping to some external server such as google or even this NTP server.

Quote:

AT+PING="192.168.1.1"
AT+PING="www.baidu.com"

Well, it couldn't be simpler

i.e. I get the time value in milliseconds and an OK response, which I listen for.

I even already have a solution for not blocking the program - even without using the flag from Timer:
1. send AT+PING="216.58.209.32"
2. Return from function
3. Do other job and periodically check response
4. If received string starts with "+PING", parse number and call user event function.

@maximus22_kr IMHO the method with ping changes nothing. In the end, you will devour the ping, which does not mean that the communication with the time server will be ok. If you have a loop that waits indefinitely for a response then that is the part of the program that should be changed. If there is no response within a certain time then you break the loop and handle the emergency.

So you can't do without the Timer after all? I thought so too.
I.e. before sending the PING I reset the flag and counter, and after the set time it will exit the loop. But letting the PING go before calling the ntp server is probably a good idea ?

tmf wrote:

@maximus22_kr If you have a loop that waits indefinitely for a response then this is the part of the program that should be changed. If there is no response within the specified time then you break the loop and handle the contingency.

That's right, I have the receipt of the time ( actually waiting for the string ) in the loop:


i was thinking of adding a small subroutine


The flag Flag_net_connect is an interrupt flag from Timer, it sets state 1 after 3 seconds.

Only, I don't know if I'm combining correctly
In the main loop, I call the NTP time reading, which I precede with a connection check.

maximus22_kr wrote:

So you can't do without the Timer after all ? I thought so too.
I.e. before sending the PING I reset the flag and counter, and after the set time it will exit the loop. But letting the PING go before calling the ntp server is probably a good idea ?

A timer is obviously advisable, but you might as well write your own delay function to wait for one of two events:
- receipt of a specified number of bytes,
- or the expiry of a set time.

Use Polish: ntp1.tp.pl or ntp2.tp.pl
and ping to them.