Example: using LwIP SNTP module and time functions
This example demonstrates the use of LwIP SNTP module to obtain time from Internet servers. See the README.md file in the upper level 'examples' directory for more information about examples.
Obtaining time using LwIP SNTP module
ESP8266 connects to WiFi and obtains time using SNTP.
initialize_sntp function for details.
Working with time
gettimeofday time asctime clock ctime difftime gmtime localtime mktime strftime
To set time,
settimeofday POSIX function can be used. It is used internally in LwIP SNTP library to set current time when response from NTP server is received.
To set local timezone, use
tzset POSIX functions. First, call
setenv to set
TZ environment variable to the correct value depending on device location. Format of the time string is described in libc documentation. Next, call
tzset to update C library runtime data for the new time zone. Once these steps are done,
localtime function will return correct local time, taking time zone offset and daylight saving time into account.