Other Peripherals - Espressif Systems ESP Faq

Chapter 4. Software framework
What should I pay attention to if I want to use the USB interface of ESP32-C3/ESP32-S3 as the unique
download interface of firmware?
• DO NOT use USB pins of ESP32-C3 (GPIO18 and GPIO19) / ESP32-S3 (GPIO19 and GPIO20) as other
peripheral functions.
• If the USB pins have to be reused as other functions in the application, the BOOT pin (GPIO9 in ESP32-C3,
GPIO0 in ESP32-S3) must be wired to manually enter the chip into the download mode.
When I attempted to download and print log via the USB interface using the command idf.py -p com35
flash monitor on Windows, I encountered the following error. What's the reason for it?
• The error is as follows:
Connecting...
Failed to get PID of a device on com35, using standard reset sequence.
• On Windows, the COM port must be configured in the upper case, not the lower case com.
How can I apply for USB VID/PID for ESP32-S series products?
• You can use default TinyUSB PIDs if your software stack is based on TinyUSB. Otherwise, you need to apply
for PID for each ESP32-S series product. For details, please refer to "usb-pids.
Is it possible to fix the COM port when downloading firmware using the USB-Serial-JTAG interface on
Windows?
• Please open the Windows CMD as the administrator and execute the following command to add
a registry entry. In this way, you can prevent incremental numbering based on the Serial number.
Then you need to restart the computer to enable the modification.
REG ADD HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\usbflags\
303A10010101 /V IgnoreHWSerNum /t REG_BINARY /d 01
→
• For more information, please refer to Prevent Windows from Increasing COM Number Ac-
cording to Serial Numbers of USB Devices <https://docs.espressif.com/projects/espressif-esp-iot-
solution/en/latest/esp32/usb/usb_device_const_COM.html>__.

4.4.18 Other Peripherals

Can the REF_TICK clock frequency be modified?
CHIP: ESP32 | ESP32-S2 | ESP32-C3
No, the REF_TICK clock is fixed.
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