How to get and sync time with sntp?

zliudr
Posts: 130
Joined: Thu Oct 03, 2019 5:15 am

How to get and sync time with sntp?

Postby zliudr » Mon Jan 06, 2020 5:53 am

I'm not sure where in azure or outside of it the sntp is called but here is a snippet of my boot message that includes the announcement that time was obtained:
I (4660) event: sta ip: 192.168.0.103, mask: 255.255.255.0, gw: 192.168.0.1
I (4660) azure: SYSTEM_EVENT_STA_GOT_IP
I (4660) azure: Got IP: '192.168.0.103'
I (4670) azure: Connected to AP success!
Initializing SNTP
ESP platform sntp inited!
I (4680) platform: The current date/time is: Mon Jan 6 05:16:06 2020
So apparently only after wifi is connected the sntp was initialized. I check the code where wifi is started, there is no sntp call. It calls to start azure client, which calls a function to start connection to azure server. I bet that is where sntp got started. I did some digging but the azure stuff is jut too deep to find anything useful.

So essentially the sntp server has been possibly started by azure client. I don't know which code is using the "platform" tag.

I just wish to obtain epoch time. Is there a function I can call to get that?

A second question: once sntp server started, is there any need to call some function once in a while to synchronize or is done in the background?

I found this example but it is quite confusing. Not a hello world type of simplicity.

https://github.com/espressif/esp-idf/bl ... ple_main.c

zliudr
Posts: 130
Joined: Thu Oct 03, 2019 5:15 am

Re: How to get and sync time with sntp?

Postby zliudr » Mon Jan 06, 2020 6:00 am

By the way, I heard that ESP32's RTC accuracy is horrible without external crystals. Is there any way to use DS3231 to substitute?

axellin
Posts: 48
Joined: Mon Sep 17, 2018 9:09 am

Re: How to get and sync time with sntp?

Postby axellin » Mon Jan 06, 2020 7:52 am

zliudr wrote:
Mon Jan 06, 2020 5:53 am

So apparently only after wifi is connected the sntp was initialized. I check the code where wifi is started, there is no sntp call. It calls to start azure client, which calls a function to start connection to azure server. I bet that is where sntp got started. I did some digging but the azure stuff is jut too deep to find anything useful.

So essentially the sntp server has been possibly started by azure client. I don't know which code is using the "platform" tag.

I just wish to obtain epoch time. Is there a function I can call to get that?

A second question: once sntp server started, is there any need to call some function once in a while to synchronize or is done in the background?
FYI:
https://github.com/espressif/esp-idf/issues/4437

Currently you cannot change NTP sync interval at runtime, it is determinated by
CONFIG_LWIP_SNTP_UPDATE_DELAY at compile time.
And there is no api to allow you to send NTP sync request immediately.

But you can use sntp_set_time_sync_notification_cb() to get notify about
the time synchronization process.

zliudr
Posts: 130
Joined: Thu Oct 03, 2019 5:15 am

Re: How to get and sync time with sntp?

Postby zliudr » Mon Jan 06, 2020 7:15 pm

Thanks! From my observation of 12 hours, time ran faster about 4.5 minutes since sntp was called. This was the sntp_example_main.c from esp-idf examples. The sntp was initialized but not updated. So the CONFIG_LWIP_SNTP_UPDATE_DELAY you were referring to, is it in menuconfig? If the example never re-synced with sntp, or at least not within reasonable time, then how is the CONFIG_LWIP_SNTP_UPDATE_DELAY going to improve it?

I have a ds3231 integrated on my prototype board. Is there any way to have esp32 use it instead of its rtc with internal rc oscillator reference?

Who is online

Users browsing this forum: Baidu [Spider], Google [Bot] and 43 guests