*
* @param period_index wakeup period setting number (0 - 4)
* @param period_us wakeup period, us
- * @note The ULP FSM requires some time to wakeup before being able to run the program.
- * Then additional time is reserved after wakeup waiting until the 8M clock is stable.
- * The FSM also requires time to go to sleep after the program execution is halted.
+ * @note The ULP FSM requires two clock cycles to wakeup before being able to run the program.
+ * Then additional 16 cycles are reserved after wakeup waiting until the 8M clock is stable.
+ * The FSM also requires two more clock cycles to go to sleep after the program execution is halted.
* The minimum wakeup period that may be set up for the ULP
- * is the total time spent on the above internal tasks.
- * For a default configuration of the ULP running at 150kHz
- * the minimum wakeup period is about 160us.
+ * is equal to the total number of cycles spent on the above internal tasks.
+ * For a default configuration of the ULP running at 150kHz it makes about 133us.
* @return
* - ESP_OK on success
* - ESP_ERR_INVALID_ARG if period_index is out of range