523aacd413
* Some components have initialization dependencies. To account for them, simple numeric priority values are introduced. * esp_system_init_fn_array moved into Flash from DRAM * System init functions defined using ESP_SYSTEM_INIT_FN now return an error code. This enables simpler and more consistent error handling in the init functions. Returning an error from an init function is now a valid approach — the startup code will print an error and abort.
System Notes
Timekeeping
The following are the timekeeping mechanisms available and their differences:
- System time (
esp_system_get_time)
Time with the origin at g_startup_time. The implementation is not handled by esp_system,
but it does provide a default implementation using RTC timer. Currently, esp_timer
provides system time, since the hardware timers are under the control of that
component. However, no matter the underlying timer, the system time provider
should maintain the definition of having the origin point at g_startup_time.
esp_timertime (esp_timer_get_time)
This is the time read from an underlying hardware timer, controlled through config. Origin is at the point where the underlying timer starts counting.
newlibtime (gettimeofday)
Timekeeping function in standard library. Can be set (settimeofday) or moved forward/backward (adjtime);
with the possibility of the changes being made persistent through config.
Currently implemented in terms of system time, as the point of origin is fixed.
If persistence is enabled, RTC time is also used in conjuction with system time.
- RTC time (
esp_rtc_get_time_us)
Time read from RTC timer.