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Nucleo-H743: Trouble setting VCP into operation on USB FS

Torsten Aurich
Associate II
Posted on November 28, 2017 at 10:53

Hello Community,

as written in my last post

https://community.st.com/message/175475-nucleo-h743zi-problems-setting-usb-fs-device-into-operation

i try to set VCP into Operation

on a Nucleo-H743ZI. Now i'm on the stage to set communication into operation.

After establishing connection to Win10 'hUsbDeviceFS.dev_state' goes

to 3 (USBD_STATE_CONFIGURED). This is the startpoint in my firmware to

try to send data to Host. For this i'm using the usb cdc interface function

uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len).

On the Host side i'm using HTerm0.8.1Beta. If i start HTerm but do not open

connection to the COM Port to H7x my software recognise this because

CDC_Transmit_FS returns USBD_BUSY. If i open the COM Port in HTerm then

my firmware transmit data to Host (under certain circumstances).

Now i found out, if the size of data that i will be transfered is

lager than 24 Bytes, the HTerm tells me something like this:

...can't open COM Port because of internal error

Did anyone have experience with a behavior like this?

Any Remarks?

Kind Regards

Torsten
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