Espressif Systems ESP Faq page 139

Chapter 4. Software framework
4.9.29 When using the release/v3.3 version of ESP8266-RTOS-SDK, how to enter Light-
sleep mode?
• First set the
ESP8266_RTOS_SDK/components/esp8266/include/esp_sleep.h.
• Then use the esp_light_sleep_start()
• You can refer to the
plementation logic.
• Please read API Reference
4.9.30 How to wake up ESP8266 in Deep sleep mode?
• The ESP8266 can only be awakened from Deep sleep mode via RTC Timer, the timing duration is set by user
via esp_deep_sleep, and GPIO16(XPD_DCDC) should be connected to EXT_RSTB through a 0 Ω resistor to
support such function. Please refer to
4.9.31 When using the ESP32-WROVER module, there is a problem of battery jitter or
abnormal power-off and power-on, causing the system to crash and fail to wake
up. What is the reason?
• Application scenario: The current is about 12 uA during sleep. When the battery is unplugged or the product is
shaken, it will cause power failure, but there is still electricity in the capacitor. During the process of discharging
ESP32 from 3.3 V to 0 V, ESP32 will fail to wake up when powered on again with 3.3 V.
• Please check whether the chip VCC and EN meet the power-on sequence requirements.
• Consider adding a reset chip to ensure normal timing.
• For ESP32 power-on and reset timing description, please refer to
4.9.32 How to flash a customized mac address?
• You can start by understanding the MAC mechanics of ESP modules, please refer to
Addresses. There are currently 2 options for burning customized MAC addresses:
• Option 1: directly flash it into efuse blk3.
• Option 2: Store in flash. It is not recommended to store the MAC address in the default NVS partition.
It is recommended to create a customized NVS partition for storing customized Mac addresses. For more
information on the use of customized MAC addresses, please refer to base_mac_address.
4.9.33 When ESP32 uses esp_timer, network communication or Bluetooth communica-
tion is abnormal. What is the reason?
• esp_timer is a high-precision hardware timer component, and some background components also use it to
complete some system tasks. When using esp_timer, please do not call delay and blocking APIs in the callback
function of the timer, and try to ensure that the function is executed as quickly as possible, so as not to affect
the performance of other system components.
• If you do not need very high time precision, please use the timer component
Espressif Systems
wake-up mode
API to enter Light-sleep mode.
esp-idf/examples/system/light_sleep/main/light_sleep_example_main.c
for API descriptions about sleep modes in ESP8266-RTOS-SDK.
related API
Submit Document Feedback
of Light-sleep mode,
descriptions.
ESP32 Datasheet.
122
please refer
example for im-
Introduction to Mac
xTimer in FreeRTOS.
Release master
to