CDC_OVF_ERR embedded resource_error ai_generated true

USB CDC: ACM data buffer overflow, 64 bytes discarded on endpoint 0x81

ID: embedded/usb-cdc-acm-buffer-overflow

Also available as: JSON · Markdown · 中文
82%Fix Rate
88%Confidence
1Evidence
2023-11-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
STM32Cube_FW_F4 v1.27.0 active — — —
TinyUSB v0.15.0 active — — —
USB CDC Class v1.2.0 active — — —

Root Cause

The USB CDC receive buffer is full because the application does not read data fast enough from the virtual COM port, causing overflow.

generic

中文

USB CDC接收缓冲区已满，因为应用程序未能足够快地从虚拟COM端口读取数据，导致溢出。

Official Documentation

https://www.st.com/resource/en/application_note/an4879-usb-hardware-and-pcb-guidelines-using-stm32-mcus-stmicroelectronics.pdf

Workarounds

  1. 85% success Implement a circular buffer in the application to store incoming USB data and process it in a lower-priority task, ensuring the CDC receive interrupt never blocks. 
    Implement a circular buffer in the application to store incoming USB data and process it in a lower-priority task, ensuring the CDC receive interrupt never blocks.
  2. 78% success Increase the polling rate of the CDC receive function in the main loop, e.g., call CDC_Receive_FS() every 1ms instead of 10ms. 
    Increase the polling rate of the CDC receive function in the main loop, e.g., call CDC_Receive_FS() every 1ms instead of 10ms.

中文步骤

  1. Implement a circular buffer in the application to store incoming USB data and process it in a lower-priority task, ensuring the CDC receive interrupt never blocks.
  2. Increase the polling rate of the CDC receive function in the main loop, e.g., call CDC_Receive_FS() every 1ms instead of 10ms.

Dead Ends

Common approaches that don't work:

  1. Increase the USB buffer size in the CDC configuration 85% fail

    Larger buffers only delay the overflow but do not fix the root cause of slow data consumption; eventually overflow still occurs.

  2. Reduce the baud rate of the virtual COM port to slow transmission 95% fail

    Baud rate is irrelevant for USB CDC; data is packet-based and the host can still send at full speed.