stm32f103_dual_vcp

An example to show how to use dual CDC VCP USB interfaces.

Hardware configuration

MCU: STM32F103C6Tx(72MHz, LQFP48, 32KB Flash, 10KB RAM)

Software Development Environment

• STM32CubeMX V4.26.1
• STM32Cube FW_F1 V1.6.1
• gcc-arm-none-eabi-7-2017-q4-major

Firmware Configureation

• Memory configuration:

  • Heap Size: 0x800
  • Stack Size: 0x800

• Perpherials

  • RCC

    • High Speed Clock (HSE): Crystal/Ceramic Resonator
    • Low Speed Clock (LSE) : Crystal/Ceramic Resonator

  • USB

    • Device (FS)

  • USART1

    • Mode: Asynchronous

  • USART2

    • Mode: Asynchronous

• MiddleWares

  • USB_DEVICE
    • Class for FS IP: Communication Device Class (Virtual Port Com)

• Pin configuration

  • USB_DM: PA11
  • USB_PM: PA12
  • USART1_TX: PA9
  • USART1_RX: PA10
  • USART2_TX: PA2
  • USART2_RX: PA3

NOTE: Check stm32f103_dual_vcp.ioc for detial.

NOTE: If you encountered the multiple re-definition issues when compiling the source code, check the Makefile and remove any duplicate files in C_SOURCES instruction.

Programming tips

USB dual CDC VCP configuration.

To support dual class in single device, you have to add IAD(Interface Association Descriptor) to USBD_CDC_CfgFSDesc or USBD_CDC_CfgHsDesc depends on which full-speed or high-speed you are using.

USBD_CDC_CfgFSDesc and USBD_CDC_CfgHSDesc can be found in /src/stm32f103_dual_vcp/Middlewares/ST/STM32_USB_Device_Library/Class/CDC/Src/usbd_cdc.c /src/stm32f103_dual_vcp/Middlewares/ST/STM32_USB_Device_Library/Class/CDC/Inc/usbd_cdc.h

There are two template files /src/stm32f103_dual_vcp/usbd_cdc-dual_vcp-template.[ch]. Use them to overwrite usbd_cdc.[ch] files.

NOTE: usbd_cdc.[ch] are generated by STM32CubeMx. So, you have to repeat the overwriting action whenever you re-generate code from STM32CubeMx.

USB event callback

There are several important USB callbacks function should be taken care of.

UART configuration

There is a switch-case in usbd_cdc_if.c::CDC_Control_FS() and usbd_cdc_if.c::CDC_Control_HS(). It is used to configure UART property. The request is sent from host via USB.

STM32 has a predefined structure USBD_CDC_LineCodingTypeDef which can be used to represent the structure of line coding request.

    USBD_CDC_LineCodingTypeDef *line_coding = (USBD_CDC_LineCodingTypeDef *)pbuf;