WAVESHARE USB to 8CH TTL: Failed to connect to ESP32-S3: Invalid head of packet (0xXX) (ESPTOOL-1333)

[KartikeyaKBoon]

Operating System

WIndows 11

Esptool Version

v5.3.dev3

Python Version

Python 3.11.15

Chip Description

ESP32-S3-WROOM-1

Device Description

No response

Hardware Configuration

No response

How is Esptool Run

from VS Code

Full Esptool Command Line that Was Run

python -m esptool --chip esp32s3 --port COM7 chip-id

Esptool Output

A fatal error occurred: Failed to connect to ESP32-S3: Invalid head of packet (0x11): Possible serial noise or corruption.
For troubleshooting steps visit: https://docs.espressif.com/projects/esptool/en/latest/troubleshooting.html

More Information

When i am using a single channel UART, I am able to flash the board successfully. But when I am using the WAVESHARE USB TO 8CH TTL, I am able to read the data on the serial monitor but not able to flash the board.

Other Steps to Reproduce

No response

I Have Read the Troubleshooting Guide

• I confirm I have read the troubleshooting guide.

[github-actions]

Hi @KartikeyaKBoon! Please be aware that (1) the following suggestions are generated by a bot and haven't been fact-checked by Espressif Systems, (2) burning eFuses and enabling security features are irreversible operations and can damage your ESP32 device. We hope that this message will help you until an Espressif Engineer looks at your issue.

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Analysis of the Issue

The error Invalid head of packet (0x11): Possible serial noise or corruption combined with the fact that a single-channel UART adapter works fine but the WAVESHARE USB to 8CH TTL does not, strongly points to a hardware/adapter issue rather than a software or chip problem.

The byte 0x11 is the XON character used in software flow control (XON/XOFF). This is a classic sign that the multi-channel USB-to-UART adapter (or its driver) has hardware or software flow control enabled, which is interfering with the serial communication.

Recommended Steps

1. Disable flow control on the serial port.
   Ensure the port used for flashing has no flow control (neither hardware RTS/CTS nor software XON/XOFF). The ESP32-S3 ROM bootloader requires:

   Setting	Value
   Baud rate	115200
   Data bits	8
   Stop bits	1
   Parity	None
   Flow control	None

   [Serial Connection]

2. Check the WAVESHARE adapter's driver settings.
   In Windows Device Manager, find the COM port for the WAVESHARE adapter, open its properties, go to Port Settings → Advanced, and make sure flow control is set to None.

3. Try a lower baud rate to rule out signal integrity issues with the multi-channel adapter:

   python -m esptool --chip esp32s3 --port COM7 --baud 9600 chip-id
   

   [Common Errors]

4. Check DTR/RTS line behavior.
   Multi-channel adapters sometimes handle DTR/RTS lines differently across channels. The ESP32-S3 uses these lines for automatic reset into download mode (GPIO0 and CHIP_PU). If the adapter doesn't assert them correctly, the chip won't enter download mode. Try manually entering download mode (hold Boot button, press EN button) before running esptool. [Flashing Troubleshooting]

5. Run esptool with --trace to get detailed output for further diagnosis:

   python -m esptool --chip esp32s3 --port COM7 --trace chip-id
   

   [Tracing Interactions]

Summary

The root cause is almost certainly the WAVESHARE 8-channel adapter enabling XON/XOFF flow control or mishandling the DTR/RTS lines, which a single-channel adapter handles correctly. Disabling flow control in the driver/port settings is the most likely fix.