| /* clear second flag */ rtc_flag_clear(RTC_TS_FLAG); /* wait for the second flag to be set */ while(rtc_flag_get(RTC_TS_FLAG) == RESET); /* set the wakeup time to 3 seconds */ rtc_alarm_set(rtc_counter_get() + 3); /* wait for the register write to complete */ rtc_wait_config_finish(); at32_led_off(LED2); /* save systick register configuration */ systick_index = SysTick->CTRL; systick_index &= ~((uint32_t)0xFFFFFFFE); /* disable systick */ SysTick->CTRL &= (uint32_t)0xFFFFFFFE; /* congfig the voltage regulator mode */ pwc_voltage_regulate_set(PWC_REGULATOR_LOW_POWER); /* enter deep sleep mode */ pwc_deep_sleep_mode_enter(PWC_DEEP_SLEEP_ENTER_WFI); /* restore systick register configuration */ SysTick->CTRL |= systick_index; /* wake up from deep sleep mode, congfig the system clock */ system_clock_recover(); at32_led_on(LED2); for(index = 0; index < 500000; index++); | 
