3254f8deae
Previously, reset over USB CDC was done by calling esp_restart from an interrupt handler. This works only until some restart hook function is registered using esp_register_shutdown_handler, and the hook function tries to do something that isn’t allowed in an interrupt handler. One such case is with Wi-Fi. When Wi-Fi driver is installed, it registers esp_wifi_stop as a shutdown handler function. However esp_wifi_stop cannot be called from an ISR, and hence we shouldn’t call esp_restart from an ISR either. This commit modifies USB CDC driver to call esp_restart by posting it to esp_timer task. Closes https://github.com/espressif/esp-idf/issues/7404
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.