Missing USB HOST CDC VID/PID found on ESP32-C3 development board (IEC-404)

[LucienMP]

Answers checklist.

• I have read the component documentation ESP-IDF Components and the issue is not addressed there.
• I am using target and esp-idf version as defined in component's idf_component.yml
• I have searched the issue tracker for a similar issue and not found any related issue.

Which component are you using? If you choose Other, provide details in More Information.

host/cdc

ESP-IDF version.

v5.5.1

Development Kit.

ESP32-S3 Dev Kit board in OTG mode connected to ESP32-C3 Spotpear board

Used Component version.

1.0.0~5

More Information.

Missing ID for the CH343 CDC-ACM UART used on this board. I suggest adding the VID/PID for Expressif CDC-ACM that seems to have been programmed into the board.

https://github.com/espressif/esp-usb/blob/master/host/class/cdc/usb_host_ch34x_vcp/include/usb/vcp_ch34x.h#L12-L15

What I found is I need to define and use the following

// VID
...
#define ESPRESSIVE_MICRO_VID       (0x303A)  // <-- ADDED

// Supported PIDs
...
#define CH343_PID_1                (0x55D3)
#define CH343_PID                  (0x1001) // <-- ADDED

Of course you also need to add it to the various lists in use, and also to the example as well.

https://github.com/espressif/esp-usb/blob/master/host/class/cdc/usb_host_ch34x_vcp/usb_host_ch34x_vcp.c#L201-L212

Board being used with new VID/PID is this one:

https://spotpear.com/wiki/ESP32-C3-desktop-trinket-Mini-TV-Portable-Pendant-LVGL-1.44inch-LCD-ST7735.html

[github-actions]

Hi @LucienMP! Please be aware that the following suggestions are generated by a bot and haven't been fact-checked by Espressif Systems. We hope that this message will help you until an Espressif Engineer looks at your issue.

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Thank you for your detailed report and suggestions.

Based on the available Espressif documentation, the ESP32-C3 only supports USB Device mode and provides a fixed-function USB Serial/JTAG controller. It does not support USB Host functionality, which means it cannot enumerate or communicate with USB devices as a host, including CDC-ACM devices such as CH343 or other USB-UART bridges. The ESP32-C3’s USB interface is strictly for device-side operation (CDC-ACM serial and JTAG), and the VID/PID for this function is Espressif’s VID (0x303A) and typically PID 0x1001 for the USB Serial/JTAG unit Does ESP32-C3 support USB Host? USB Serial/JTAG Controller Console ESP32-C3 Technical Reference Manual.

The USB Host CDC-ACM drivers and related component support (such as usb_host_cdc_acm and usb_host_ch34x_vcp) are available for ESP32-S2, ESP32-S3, ESP32-H4, and ESP32-P4, but not for ESP32-C3. This is confirmed in the component documentation and the supported targets listed for these drivers usb_host_cdc_acm component usb_host_ch34x_vcp component.

If you are using an ESP32-S3 as the host (in OTG mode) and connecting it to an ESP32-C3 board acting as a device, the ESP32-C3 will present itself as a CDC-ACM device with VID 0x303A and PID 0x1001. If the CH343 (or similar) is used as a USB-UART bridge on the ESP32-C3 board, its VID/PID should match the chip manufacturer's assignment (e.g., WCH for CH34x chips), unless the board designer has reprogrammed it.

If you have found that the ESP32-C3 board is presenting itself with Espressif’s VID (0x303A) and PID (0x1001) as a CDC-ACM device, and this combination is not currently recognized by the usb_host_ch34x_vcp driver, your suggestion to add these VID/PID values to the driver’s supported list is reasonable. However, the official Espressif documentation does not explicitly mention support for this scenario or provide a list of all recognized VID/PID pairs for the CH34x driver.

Summary:

• ESP32-C3 only supports USB Device mode (CDC-ACM/JTAG), not USB Host.
• The VID/PID for ESP32-C3’s USB Serial/JTAG is 0x303A/0x1001.
• The usb_host_ch34x_vcp driver is not intended for ESP32-C3, but for host-capable chips (ESP32-S2/S3/H4/P4).
• If you are using ESP32-S3 as host and ESP32-C3 as device, and the device presents 0x303A/0x1001, adding this VID/PID to the host driver’s supported list is a valid workaround, but this is not officially documented.

If you need official support for this VID/PID combination in the usb_host_ch34x_vcp driver, it would be best to open a feature request or pull request in the esp-usb repository, as the current documentation does not list this as a supported or intended use case.

References:

• Does ESP32-C3 support USB Host?
• USB Serial/JTAG Controller Console
• usb_host_cdc_acm component
• usb_host_ch34x_vcp component

If you need further clarification or official support for this scenario, please let us know!

[tore-espressif]

Hello @LucienMP, and thank you for the detailed report.

The behavior you observed comes from the fact that many USB-to-serial chips marketed as “CDC-ACM” do not implement the CDC-ACM class specification. Devices such as the CH340 or CH343 expose a vendor-specific interface that only resembles CDC-ACM. Their protocol diverges from the specification, and the driver must account for that.

In the CH34x driver, only set_control_line_state and line_coding are provided explicitly; all other operations fall back to the generic CDC implementation. If your application does not rely on these two control functions, the distinction between true CDC-ACM and the vendor variant remains invisible.

For the USB-Serial-JTAG interface in the ESP32-C3, the correct driver is the standard CDC-ACM implementation:
https://github.com/espressif/esp-usb/tree/master/host/class/cdc/usb_host_cdc_acm

We will update our examples to reduce this ambiguity in future.