Do the Virtual COM Port drivers work with Windows 7?

[Harry McKee]

I have tried installing and running projects using the USB_Device/CDC_Standalone project for both the STM32L476G-EVAL and the STM32F779I-EVAL boards, but every time I connect the board using the USB FS port, I get a driver error "This device cannot start. (Code 10)"

After uninstalling and installing the VCP drivers multiple times (using STLinkUSBDriver.dll v4.4.0.0 and Virtual COM Port driver 1.3.1.0 from VCP_V1.5.0_Setup_W7_x64_64bits.exe) , it never works. I've searched through the ST forums but have had no luck finding any documentation for this issue.

After a little more research, I found the stm32l4xx_ll_usb.c driver is hard faulting in USB_WritePacket.

The hard fault is occurring during the write of 0x200001BE USBD_StringSerial. See attached image:

I also changed the heap size according to the information in the FAQ https://community.st.com/s/article/FAQ-USB-device-not-recognized

This had no effect on the hard fault.

[Mon2]

Hi. Please review this thread:

https://community.st.com/s/question/0D50X00009XkWhuSAF/stmicroeletronics-virtual-com-port-this-device-cannot-start-code-10-windows-81

and try the driver package from here:

https://my.st.com/content/my_st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-utilities/stsw-link009.license%3d1518543103787.html

[Harry McKee]

Thank you for the reply. I should have said that I have already downloaded and installed (multiple times) both the VCP driver 1.5.0 in VCP_V1.5.0_Setup_W8_x64_64bits.exe and the ST-Link driver in STSW-LINK009.

I am already running the latest drivers from ST for both ST-Link and the Virtual COM Port.

[Harry McKee]

Looks like my problem is similar to this thread: https://community.st.com/s/question/0D50X0000Amj7LqSQI/stm32f407vgtx-cdc-error-driver

After increasing both the stack and heap, the hard fault still persists.

[Pavel A. · Accepted solution]

Ah, the fault in USB_WritePacket.

This is simply because of unaligned 32-bit access. Already reported here earlier.

Try to change this way :

HAL_StatusTypeDef USB_WritePacket(USB_OTG_GlobalTypeDef *USBx, uint8_t *src, uint8_t ch_ep_num, uint16_t len, uint8_t dma)
{
  uint32_t USBx_BASE = (uint32_t)USBx;
  uint32_t *pSrc = (uint32_t *)src;
  uint32_t count32b, i;
 
  if (dma == 0U)
  {
    count32b = ((uint32_t)len + 3U) / 4U;
    for (i = 0U; i < count32b; i++)
    {
      if (((uint32_t)pSrc & 0x3) == 0) {
        USBx_DFIFO((uint32_t)ch_ep_num) = *((__packed uint32_t *)pSrc);
      } else {         //<<< UNALIGNED
        uint32_t v;
        memcpy(&v,pSrc,4);
        USBx_DFIFO((uint32_t)ch_ep_num) = v;
      }
      pSrc++;
    }
  }
 
  return HAL_OK;
}

(fast and dirty fix, not optimized, sorry)

-- pa

[Harry McKee]

Thanks for info, I was going to try that next. I've looked for more details on the unaligned memory access, but only found a couple posts mentioning this:

https://community.st.com/s/question/0D50X00009XkgYUSAZ/stm32l4-usb-otg-host-driver-for-cdcncm

https://community.st.com/s/question/0D50X0000AiyCdYSQU/unaligned-memory-access-in-function-usbwritepacketusbreadpacket-stm32fcubefwf4v1240

The latest STM32L4 firmware doesn't contain USB_WritePacket with the DMA argument. I see the alternate version of USB_WritePacket with dma is in the F7 firmware.

Do you have any links to the previous error report?

[Pavel A.]

Yes, it is the 2nd your link.

Unfortunately, the software team does not have a bug tracker visible for us, and isn't willing to make commitment for updates.

-- pa

[KFite.1]

Hi,

I want to add useful info about one more solution. 

You can emulate serial port in a system on several different Windows versions and interconnect them virtually. So if you have some problem or may be want alternative software, you can try Serial Port Emulator https://www.virtual-serial-port.org/

And i want to say that it is not free, but you have 14 day fully-functional trial.