ESP32-S3 loads sketch but no COM port appears / serial monitor unresponsive

[Enigma993]

Board

ESP32-S3 – Sparkle IoT XH-S3E with integrated touchscreen (AXS15231B)

Device Description

ESP32-S3 development board with integrated 3.5" SPI touchscreen. Model: Sparkle IoT XH-S3E. Includes USB-C port, 16MB flash, 2MB PSRAM, and unknown touchscreen driver (AXS15231B). No external connections used during tests.

Hardware Configuration

Board powered via USB-C from PC. No external peripherals connected. No GPIOs in use. Using default boot mode with no changes to hardware configuration.

Version

latest stable Release (if not listed below)

IDE Name

Arduino IDE and PlatformIO (VSCode)

Operating System

Windows 10

Flash frequency

80 MHz

PSRAM enabled

yes

Upload speed

460800

Description

Hi,
I'm working with an ESP32-S3 board (Sparkle IoT model XH-S3E with integrated screen), and I'm having trouble with the USB COM port:

• The sketch uploads correctly via esptool.py or Arduino IDE.
• However, no COM port shows up after flashing.
• Serial monitor does not receive any data.
• The board makes the “USB disconnect” sound in Windows repeatedly (tin-tin loop).
• I've already tested:
  • Different USB cables and ports
  • Holding BOOT and RESET in different sequences
  • Sketches known to work on other ESP32-S3 boards
  • PlatformIO and Arduino IDE (both behave the same)

This is frustrating because it seems the chip is alive (code uploads fine), but the USB CDC port is not initialized after reboot.

Does this board require a special bootloader or extra steps for USB CDC to work?

Any help is welcome. I’ve spent many hours debugging this.

Thanks!

Sketch

Simple sketch with Serial.begin(115200) and basic loop. Also tested with known working examples from GitHub using USB CDC on ESP32-S3:

void setup() {
  Serial.begin(115200);
}

void loop() {
  Serial.println("Hello Robles");
  delay(1000);
}

Debug Message

No output from Serial Monitor.

After flashing via esptool.py, the board disconnects and reconnects in a loop (Windows "tin-tin" USB sound repeats). No COM port appears in Device Manager.

No debug messages are shown on the serial monitor, even with sketches known to work on ESP32-S3.

Tried multiple cables, ports, and host PCs.

Other Steps to Reproduce

1. Connect the ESP32-S3 board via USB-C to a Windows 10 PC.
2. Open Arduino IDE or use esptool.py to upload a simple sketch with Serial.begin(115200).
3. After upload, the board disconnects and reconnects repeatedly (USB sound loop).
4. No COM port is detected in Device Manager.
5. Open Serial Monitor – no output is shown.

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[me-no-dev]

You did not point out the version of Arduino that you are using. Also please provide the board settings in the IDE

[SuGlider]

try this and check if it compiles:

void setup() {
  Serial.begin();  // No Baud Rate is only allowed when USB CDC On Boot is enabled. Otherwise compilation will fail.
}

void loop() {
  Serial.println("Hello Robles");
  delay(1000);
}