usbd_cdc_if.c buffer addresses

[mnusa2]

While moving the sources to STM32CubeIDE I noticed somewhat doubtful code. This may be for a purpose or an error. I have not noticed any erroneous behaviour based on this.

USBD_CDC_SetTxBuffer() and USBD_CDC_SetRxBuffer() use the same buffer address UserRxBufferFS.

From usbd_cdc_if.c istarting line 150. / Private functions ---------------------------------------------------------/ /**

• @brief Initializes the CDC media low layer over the FS USB IP
• @retval USBD_OK if all operations are OK else USBD_FAIL / static int8_t CDC_Init_FS(void) { / USER CODE BEGIN 3 / / Set Application Buffers / USBD_CDC_SetTxBuffer(&hUsbDeviceFS, UserRxBufferFS, 0); USBD_CDC_SetRxBuffer(&hUsbDeviceFS, UserRxBufferFS); return (USBD_OK); / USER CODE END 3 */ }

[mnusa2]

Just to note, the file is for Firmware.

[freepdk]

This is just during initialization. It sets a TX buffer of 0 length (so any pointer is fine here).

Later when there is something to send (in "CDC_Transmit_FS") you can see that the buffer supplied from caller is given to USBD_CDC_SetTxBuffer.

So all is fine.