bugs in USBSerial & usbd_conf.c

[stefaandesmet2003]

• Arduino IDE version: 1.8.8
• STM32 core version: github latest
• OS: linux ubuntu
• board: bluepill
  The 2 main issues i have :

1. USBSerial gives errors because the pma buffers for the CDC_OUT_EP endpoint is not correctly initialized in usbd_conf.c. Errors I have : hard fault when usb is plugged out and back in; dtr/rts not set correctly, serial monitor in arduino plugin in vscode corrupts the pma buffer (still don't understand why.., because cat /dev/ttyACM0 and arduino serial monitor work ok)
   This code solves the issue :
   // defines have to align with usbdc_cdc.h #define CDC_IN_EP 0x81U /* EP1 for data IN */ #define CDC_OUT_EP 0x01U /* EP1 for data OUT */ #define CDC_CMD_EP 0x82U /* EP2 for CDC commands */ HAL_PCDEx_PMAConfig(pdev->pData, 0x00, PCD_SNG_BUF, 0x40); HAL_PCDEx_PMAConfig(pdev->pData, 0x80, PCD_SNG_BUF, 0x80); HAL_PCDEx_PMAConfig(pdev->pData, CDC_IN_EP, PCD_SNG_BUF, 0xC0); HAL_PCDEx_PMAConfig(pdev->pData, CDC_OUT_EP, PCD_SNG_BUF, 0x110); HAL_PCDEx_PMAConfig(pdev->pData, CDC_CMD_EP, PCD_SNG_BUF, 0x100);

2. CDC_Flush() can be called without CDC driver initialized, resulting in address 0 reference in USBD_CDC_SetTxBuffer.
   This happens for instance when doing UsbSerial.print(...) with usb disconnected until the internal buffer fills up and code calls CDC_Flush(), or when calling UsbSerial.flush()

3. what's the advantage of using a timer for USBSerial? It can be implemented without by flushing to PMA on every write. It looks like unnecessary use of a timer peripheral (implementation in mbed or Roger Clark's repo)

[fpistm]

@stefaandesmet2003
did you test with #419 which includes several improvements?

[stefaandesmet2003]

unfortunately no ! will definitely try.

[stefaandesmet2003]

nice work! that branch solves my problems. The cdc_queue works well, blocks the write function once the queue is full; i guess that's intended behaviour.
issue closed :)
Thanks,
Stefaan

[fpistm]

Welcome.
All congratulations go to @makarenya ;)
I've only reformat PR.