Chapter 5. Hardware related
5.3.26 Where can I nd the design reference for the external 32 kHz crystal of ESP32
modules?
• Please refer to Section RTC (optional) in the ESP32 Hardware Design Guidelines.
5.3.27 Does the ash of ESP32 modules support 80 MHz QIO access mode?
• ESP32 modules support 80 MHz QIO access mode.
• You are recommended to load the second-stage bootloader in QIO mode, as QE is not set by default in some
ash status registers.
5.3.28 How to congure the RMII synchronous clock for the Ethernet of ESP32?
• To run a test, please refer to esp-idf/examples/ethernet/basic.
• When GPIO0 provides clock output for PHY, the Ethernet connection of the IP101 PHY chip can be unstable.
Therefore, you are recommended to connect a 50 MHz crystal to PHY with GPIO0 as input.
• Because of the characteristics of GPIO0, the IO should be set to control the enable pin of PHY.
• Please read Ethernet document.
• You may also refer to 1SCH_ESP32-ETHERNET-KIT Schematics.
5.3.29 How can I hard reset ESP8266? Is hard reset active low or active high? What are
the requirements for reset?
• The Pin32 EXT_RSTB of ESP8266 is the reset pin. This active low pin has an internal pull-up resistor. To
prevent external factors triggering a restart, it is recommended that the EXT_RSTB cabling be as short as
possible and an RC circuit be added to the EXT_RSTB pin.
• The CHIP_EN pin of ESP8266 can also be used as a hard reset pin. When you use the CHIP_EN pin as a
reset pin, the reset is active low. To reset and restart ESP8266, the input level should be lower than 0.6 V and
last for more than 200 μs. It is recommended to use the CHIP_EN pin for chip reset. For more information,
please refer to Section Reset in the ESP8266 Hardware Design Guidelines.
5.3.30 What does the term NC mean in Espressif schematics?
• NC is the acronym of“No Component”. If you see a pull-up resistor is marked NC as shown in
the gure below, it indicates that the component is not installed.
5.3.31 How can I use multiple antennas with ESP32-S2?
• Using multiple antennas with ESP32-S2 is similar to that with ESP32. You may refer to ESP32-WROOM-DA
Datasheet.
• For detailed instructions, please refer to ESP-IDF Programming Guide.
• You can add an RF switch to select antennas.
Espressif Systems 160
Submit Document Feedback
Release master
To Next Page
Loading...