System Time - Espressif ESP32-S2 Programming Manual

Chapter 2. API Reference
Return
• ESP_OK: Successfully reset the TWDT on behalf of the currently running task
• ESP_ERR_NOT_FOUND: Error, the current running task has not subscribed to the TWDT
• ESP_ERR_INVALID_STATE: Error, the TWDT has not been initialized yet
esp_err_t esp_task_wdt_delete(TaskHandle_t
Unsubscribes a task from the Task Watchdog Timer (TWDT)
This function will unsubscribe a task from the TWDT. After being unsubscribed, the task should no longer
call esp_task_wdt_reset(). If the task is an IDLE task, this function will automatically disable the calling of
esp_task_wdt_reset() from the Idle Hook. Calling this function whilst the TWDT is uninitialized or attempting
to unsubscribe an already unsubscribed task from the TWDT will result in an error code being returned.
Return
• ESP_OK: Successfully unsubscribed the task from the TWDT
• ESP_ERR_INVALID_ARG: Error, the task is already unsubscribed
• ESP_ERR_INVALID_STATE: Error, the TWDT has not been initialized yet
Parameters
• [in] handle: Handle of the task. Input NULL to unsubscribe the current running task.
esp_err_t esp_task_wdt_status(TaskHandle_t
Query whether a task is subscribed to the Task Watchdog Timer (TWDT)
This function will query whether a task is currently subscribed to the TWDT, or whether the TWDT is initial-
ized.
Return :
• ESP_OK: The task is currently subscribed to the TWDT
• ESP_ERR_NOT_FOUND: The task is currently not subscribed to the TWDT
• ESP_ERR_INVALID_STATE: The TWDT is not initialized, therefore no tasks can be subscribed
Parameters
• [in] handle: Handle of the task. Input NULL to query the current running task.

2.6.25 System Time

Overview
System time can be kept using either one time source or two time sources simultaneously. The choice depends on the
application purpose and accuracy requirements for system time.
There are the following two time sources:
• RTC timer: Allows keeping the system time during any resets and sleep modes, only the power-up reset leads
to resetting the RTC timer. The frequency deviation depends on an
only in sleep modes, in which case the time will be measured at 6.6667 us resolution.
• High-resolution timer: Not available during any reset and sleep modes. The reason for using this timer is
to achieve greater accuracy. It uses the APB_CLK clock source (typically 80 MHz), which has a frequency
deviation of less than ±10 ppm. Time will be measured at 1 us resolution.
The settings for the system time source are as follows:
• RTC and high-resolution timer (default)
• RTC
• High-resolution timer
• None
It is recommended to stick to the default setting which provides maximum accuracy. If you want to choose a different
timer, configure CONFIG_ESP32S2_TIME_SYSCALL
RTC Clock Source
The RTC timer has the following clock sources:
Espressif Systems
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in project configuration.
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RTC Clock Source and affects accuracy
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