Espressif Systems ESP Faq page 16

5.3.45 Does ESP32 support connection to an external SD NAND flash chip (instead of the default
NOR flash chip) via the SPI0/SPI1 interface for storing application firmware?
5.3.46 Does it support to connect a second PSRAM chip externally based on the ESP32-S3R8
5.3.47 Could you please provide the 3D model and Footprint files of the ESP32-S3-WROOM-1
module?
5.3.48 Does ESP32/ESP32-S2/ESP32-C3/ESP32-S3 support powering the RTC power domain
only to keep the chip working with low power consumption?
5.3.49 How can I improve the EMC performance?
5.3.50 Why do I need to connect a 499 Ω resistor to U0TXD for ESP32-S3?
5.3.51 How to calibrate the ESP32-S3 ADC in hardware?
5.3.52 How to design an automatic download circuit based on the ESP32 series chip?
5.3.53 Which crystal oscillator should be used on the ESP8266 chip?
5.3.54 Do the ESP32-C2, ESP32-C3 and ESP32-C6 chips support external PSRAM chips?
5.3.55 When the ESP32-C3 is powered by a battery, it may fail to start if the supply voltage
gradually decreases, for example, when the battery is fully discharged and then recharged.
In such cases, the solution could only be disconnecting the battery from the ESP32-C3 and
reconnect a fully charged battery, or to connect a voltage regulator diode between the 3.3
V pin and the EN pin to ensure the chip starts properly. What is the root cause of this
situation? Is there an optimal solution?
5.4 RF Related . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
5.4.1 Does the RF performance of an ESP32 module degrade if it runs with a 2.8 V supply?
5.4.2 What are the modulation methods supported by ESP chips?
5.4.3 How can I get the RF related information (e.g., antenna specification, antenna pattern, etc.)
for certification?
5.4.4 Why does ESP32 automatically reduce its transmit power when it uses the RF Test Tool at
80 °C?
5.4.5 How to improve the receiving distance and strength of Wi-Fi signals for ESP32-WROVER-
E? (Application scenario: Wi-Fi probe)
5.4.6 How to write phy_init data to flash ?
5.4.7 How can I optimize the second harmonic and other spurious signals created by my own
products?
5.4.8 How can I suppress the harmonics of 80 MHz?
5.4.9 Is manual power calibration required for the Espressif modules that connect to external
antennas?
5.4.10 What is the default duty cycle for the "default"level when using the "RF Test Tool"to
set the Wi-Fi "TX continues"mode?
5.5 Process and ESD Protection
5.5.1 What should be paid attention to during the ESP32 ESD test?
5.6 Production Test
5.6.1 Why can some modules download firmware normally when using DIO/DOUT, but en-
counter program abnormality when using QOUT/QIO?
5.6.2 How to get the production test tool?
5.6.3 When I use the esptool.py burn_custom_mac command to write the user-defined
MAC address, why is the MAC address read by the esptool.py read_mac command
still factory default?
5.6.4 When downloading bin files to ESP32-WROVER-E (16 MB flash) using Flash Download
Tool, multiple separate bin files can be downloaded successfully, but downloading the com-
bined firmware (12 MB) failed. Why?
6 Test verification
6.1 Power Consumption Verification
6.1.1 Why does ESP32 reboot when it is woken up from Deep-sleep mode?
6.1.2 What sleep modes does ESP32 support? What is the difference between them?
6.1.3 Can ESP32 in Deep-sleep mode be woken up by any RTC_GPIO?
6.1.4 What is the power consumption of ESP8266 when the CHIP_PU pin is at the low level?
6.1.5 Why does the minimum current of ESP32 in Light-sleep increase when the timer is not
used as a wakeup source?
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