It finally connects to Host and provides Virtual COM port (for User USB connector on Nucleo board).

NOTE: There are two Virtual COM ports:

1. CN1-USB PWR - this is ST-Link connector. It provides always Virtual port named STMicroelectronics STLink Virtual COM Port (COMx) under Windows.

   Under Linux it is visible like (output from dmesg):

   usb 2-1: new full-speed USB device number 2 using ohci-pci
   usb 2-1: New USB device found, idVendor=0483, idProduct=374b
   usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
   usb 2-1: Product: STM32 STLink
   usb 2-1: Manufacturer: STMicroelectronics
   usb 2-1: SerialNumber: xxxxxxxxxxxxxxxxxxxxxxxx
   cdc_acm 2-1:1.2: ttyACM0: USB ACM device
   usbcore: registered new interface driver cdc_acm
   cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
   

   Please notice idVendor=0483, idProduct=374b

   This port is connected to USART3 of MCU. If you want to use this serial port you can look into example in:

   ~/STM32Cube/Repository/STM32Cube_FW_F7_V1.15.0/Projects/STM32F767ZI-Nucleo/Examples/UART/`
   

   provided by vendor.

2. CN13-User USB - it is USB directly attached to MCU. It is visible under Windows as STMicroelectronics Virtual COM Port (COMx). (Notice "missing" STLink word). This port is used in this project.

   Please also notice different "idProduct" ("idVendor" is same as above): idVendor=0483, idProduct=5740

Current function:

• red LED D3 lights on fatal error

• blue LED D2 is blinking (to signal that CPU is running)

• green LED D1 - you can control it by sending 1 or 0 character to Virtual COM port on CN13-User USB. All other characters are currently silently ignored. This code is implemented in file Src/usbd_cdc_if.c function:

  static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len);

• OS: Debian Linux 9.9/amd64
• CubeMX 5.3.0, installer: en.STM32CubeMX_v5-3-0.zip
• Firmware: STM32Cube_FW_F7_V1.15.0
• IDE: SW4STM32 v2.9 for Linux/64-bit, installer: install_sw4stm32_linux_64bits-v2.9.run

WARNING! The Code Generated by CubeMX 5.3.0 is buggy (at least for firmware STM32Cube_FW_F7_V1.15.0) - you must apply this fix to generated code:

--- a/Src/usbd_conf.c
+++ b/Src/usbd_conf.c
@@ -206,11 +206,11 @@ void HAL_PCD_ResetCallback(PCD_HandleTypeDef *hpcd)
 { 
   USBD_SpeedTypeDef speed = USBD_SPEED_FULL;
 
-  if ( hpcd->Init.speed == PCD_SPEED_HIGH)
+  if ( hpcd->Init.speed == USB_OTG_SPEED_HIGH)
   {
     speed = USBD_SPEED_HIGH;
   }
-  else if ( hpcd->Init.speed == PCD_SPEED_FULL)
+  else if ( hpcd->Init.speed == USB_OTG_SPEED_FULL)
   {
     speed = USBD_SPEED_FULL;
   }

Also in my case I need to replace:

• __packed="__attribute__((__packed__))" with
• __packed="__attribute__((packed))" to avoid build errors (in C/C++ Build -> Settings -> MCU GCC Compiler -> Preprocessor).

NOTE: To avoid problems please use this directory structure:

• /home/ansible/projects/stm32-usb-cdc1/ - path of this project
• /home/ansible/STM32Cube/Repository/STM32Cube_FW_F7_V1.15.0/ - path of firmware package STM32Cube_FW_F7_V1.15.0

If you plan to connect CN13-User USB to Windows 7 or Windows 8.x you may need to install STM32 Virtual COM Port Driver.

Important note: The Nucleo board MUST be powered on (for example connected to PC using CN1-USB PWR) - before connecting CN13-User USB to Host. Doing otherwise may damage Nucleo board!

--hp