STM32F4 USB Virtual Com Port weird problem/settings solved?

[Christoph Eschenbach]

Posted on January 30, 2017 at 18:23

Hey there,

I am trying to put up a VCP for Nucleo144 STM32F429 and had hard time figuring out why i cannot connect with my Terminal Program board with the CubeMX generated Sourcecode.

I dont know why but this worked for me now:

In CubeMX:

   Board Selection->STM32->Nucleo144->F429ZI

Pinout Tab:

   Peripherals:

      USB_OTG_FS->Device Only

      RCC->Enable HSE->Bypass

MiddleWares:

   Enable USB_DEVICE->Communication Device Class(Virtual Com Port)

Clock Configuration:

   PLL Source Mux: HSE 8MHz         /M= 4, *N = 168, /P = 2, /Q =7

   System Clock Mux: PLLCLK-> 168MHz

   APB1 peripheral clocks 42 MHz

Configuration Tab:

   Connectivity->USB_FS->Parameter Settings->VBUS Sensing-> Disabled

   Project Settings->Linker Settings:

   Heap from 0x200 to 0x2000

   Stack from 0x400 to 0x600

Project Settings

In IAR Embedded Workbench:

      USB_HS_MAX_PACKET_SIZE  from 512 to 256

      CDC_DATA_HS_MAX_PACKET_SIZE from 512 to 256

      (this doesnt really affected the problem so i changed it back to 512 since im using FS-mode)

Still I cannot connect via a Terminal from Host PC.

So i searched and now this happens:

   Back in CubeMX taking a harder look at USB_DEVICE in Configuartion Tab.

   I changed USBD_MAX_STR_DESC_SIZ the default 512 to 64 bytes, because description says between 1 and 64. Why    default is 512 then?

->Still cannot connect.

   Changed USBD_DEBUG_LEVEL to 3.

I finally can connect to device via Terminal.

I will try to rebuild this scenario tomorrow to see if this option really making me that trouble.

Could these settings have such impact on the right configuration?

[Imen.D]

Posted on January 30, 2017 at 22:55

Hi,

Try to change the buffers size and HS max packet size from 512 to 64, as t

he maximum packet size for full speed devices is 64 bytes. 

Also, i

ncrease the heap and stack size. 

Please keep me updated on your 

scenario results.

Imen

[Christoph Eschenbach]

Posted on January 31, 2017 at 08:51

stack and heap size were increased...

the buffer and packet size should only affect when i start with transmit and receive calls?

I made quick rebuild this morning with following result:

Rebuild:

CubeMx

      Board Selection->STM32->Nucleo144->F429ZI

Pinout Tab:

   Peripherals:

      USB_OTG_FS->Device Only

      RCC->Enable HSE->Bypass

   MiddleWares:

      Enable USB_DEVICE->Communication Device Class(Virtual Com Port)

   Clock Configuration:

      PLL Source Mux: HSE 8MHz         /M= 4, *N = 168, /P = 2, /Q =7

      System Clock Mux: PLLCLK-> 168MHz

      APB1 peripheral clocks 42 MHz

USB_FS Configuration

   VBUS sensing Disable

   USB_DEVICE Configuration

   USBD_MAX_STR_DESC_SIZ from 512 to 64

   USBD_DEBUG_LEVEL to 3

Project Settings:

   ->HAL Settings: Enable Full Assert

   ->Code Generator: Copy only the necessary libary files

Generate Code

In IAR no changes…

I made no Transmit or Receive calls and i can connect to device via terminal program.

CubeMX -> USBD_DEBUG_LEVEL to 0

Generate Code

In IAR no changes..

   I made no Transmit or Receive calls and i get Error in Terminal programm

CubeMX -> USBD_DEBUG_LEVEL to 1

   I made no Transmit or Receive calls and i get Error in Terminal programm

CubeMX -> USBD_DEBUG_LEVEL to 2

   I made no Transmit or Receive calls and i can connect to device

So there must be any effect of USBD_DEBUG_LEVEL to initialization or connection?

I will know test Transmit and Receiving on the working project and hope upcoming problems

can be more easily managed then this one.

[Christoph Eschenbach]

Posted on January 31, 2017 at 12:47

In the working project i just added a few lines source code to generate a array with Data which i send after a Delay

with the CDC_Transmit_FS():

  while (1)

  {    HAL_Delay(1000);    CDC_Transmit_FS(testData, 8);

  }

without any changes to Buffer etc. actually i am wondering this works because I made no changes to the generated source code.

USB_HS_MAX_PACKET_SIZE and CDC_DATA_HS_MAX_PACKET_SIZE are still 512

and APP_RX_DATA_SIZE and APP_TX_DATA_SIZE is still 4

why is it working?