Espressif Systems ESP Faq page 15

5.2.2 According to the schematic of ESP32-LyraT-Mini, the analog output of the ES8311 codec
chip is connected to the input of the ES7243 ADC chip. What is the purpose of this?
5.2.3 When using the ESP32-MINI-1 module, the serial port printed the follows log when pow-
ered on. What could be the reason?
5.3 Hardware design
5.3.1 The I2S pins of ESP32 are scattered. Can I route I2S signals to adjacent pins? For exam-
ple, to GPIO5, GPIO18, GPIO23, GPIO19, and GPIO22, or to GPIO25,
GPIO26, GPIO32, and GPIO33.
5.3.2 How can I stop the power loss of VDD3P3_RTC after ESP32 enters Light-sleep mode?
5.3.3 What should be noted when I configure the pins of ESP32?
5.3.4 What is the voltage tolerance of GPIOs of ESP chips?
5.3.5 What are the power supply specifications for ESP8266?
5.3.6 Do Espressif Wi-Fi modules support single-layer PCBs?
5.3.7 What should be noted when I power ESP8266 with batteries?
5.3.8 Where can I get the footprint of ESP32 Series?
5.3.9 For ESP32-S2 chips, can I have audio connection when the DVP camera interface is in
5.3.10 What should be noted when I assign I2C signals to GPIO0 and GPIO4 of ESP32 modules?
5.3.11 When the external flash is connected to GPIO6 ~ GPIO11, can they be set as SPI pins?
5.3.12 Do I need to connect an external crystal when using the ESP8285 chip?
5.3.13 Where can I find the reference design for connecting an external PSRAM to
5.3.14 Can I use ESP32 to play music with PWM or DAC?
5.3.15 Why is the suggested voltage range of ESP32 modules diffrent from that of ESP32 chips?
5.3.16 Why does it take a longer time to erase the flash of self-developed modules than that of
Espressif modules?
5.3.17 Why does the current surge when ESP8266 is powered on?
5.3.18 What choices do I have when configuring the RMII clock for the Ethernet of ESP32?
5.3.19 What kind of socket is used on ESP32-LyraT development boards to connect a speaker?
5.3.20 For modules housing ESP32, which pins cannot be set by users?
5.3.21 Which is the reset pin of ESP32?
5.3.22 What should be noted when I design the power supply for ESP8266?
5.3.23 When I use the TOUT pin of ESP8266 to collect ADC sample signals, will the pins be
damaged if the voltage is greater than 1.0 V?
5.3.24 For modules with PCB antennas, what should be noted when I design the PCB and the
housing of the antenna?
5.3.25 Can GPIO 34 ~ GPIO39 of ESP32 be used as UART RX pins?
5.3.26 Where can I find the design reference for the external 32 kHz crystal of ESP32 modules?
5.3.27 Does the flash of ESP32 modules support 80 MHz QIO access mode?
5.3.28 How to configure the RMII synchronous clock for the Ethernet of ESP32?
5.3.29 How can I hard reset ESP8266? Is hard reset active low or active high? What are the
requirements for reset?
5.3.30 What does the term NC mean in Espressif schematics?
5.3.31 How can I use multiple antennas with ESP32-S2?
5.3.32 Does ESP32-C3F SPI CS0 pin need an external 10 kΩ pull-up resistor?
5.3.33 Is there any hardware design reference for ESP-Skainet Speech Recognition?
5.3.34 Is it necessary to connect a 32 kHz RTC crystal?
5.3.35 For the ESP32-MINI-1 module, is there a component library for Altium Designer?
5.3.36 Can I change the input voltage of UART0 of ESP8266 from 3.3 V to 1.8 V?
5.3.37 Is the level of UART0 of ESP8266 determined by VDD (VCC_WIFI) or VDDPST
(VCC_CODEC_IO)?
5.3.38 What should be noted when I connect an external PSRAM to ESP32-D2WD?
5.3.39 When the VDD power supply of ESP32 slowly rises from 0 V to 3.3 V, why does the chip
not start as usual?
5.3.40 When using the ESP32-WROOM-32D module, can I set GPIO12 for other uses?
5.3.41 When connecting an external flash to ESP32-WROOM-32D module, is it possible if I do
not use GPIO6 ~ GPIO11 pins?
5.3.42 Do I need to add a shielding case to the PCB of ESP32 modules?
5.3.43 Do I must use GPIO0, GPIO1, or GPIO3 of ESP32 as the I2S CLK pin?
5.3.44 Does the ESP32-U4WDH chip support external PSRAM chips?
xiv
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
. . . . . . . . . . . . . . . . . . . . . . . . . . 155
. . . . . . . . . . . . . . . . . . . 156
. . . . . . . . . . . . . . . . . . 156
. . . . . . . . . . . . . . . . . . 156
. . . . . . . . . . . . . . . . . . . . . . . 156
. . . . . . . . . . . . . . . . . . . . 157
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
. . . . . . . . . . . . . . . . . . . . . . . . 159
. . . . . . . . . . . . . . . . . . . 160
. . . . . . . . . . . . . . . . . . . . . 160
. . . . . . . . . . . . . . . . . . . . . . 161
. . . . . . . . . . . . . . . . 155
. . . . . . . . . . . . . . . 156
. . . . . . . . . . 157
ESP32-D2WD?157
. . . . . . . . . . . . . . . . 158
. . . . . . . . . . . . . . 159
. . . . . . . . . . . 159
. . . . . . . . . . . . . . 159
. . . . . . . . . . . 160
. . . . . . . . . 160
. . . . . . . . . . 161
. . . . . . . 161
. . . . 161
. . . . . . . 162
. . . . . . . 162
. . . . . 162
. . . . . . . . . . . . . 163
. . . . . . . . . 163
. . . . . . . . . . . . . . 163
. . . 154
. 155
use?157
157
. . 157
158
. . . 158
. 158
. 160