Skip to main content
S
sagit
Visitor II
July 1, 2024
Question

USB CDC is sending bad data.

  • July 1, 2024
  • 1 reply
  • 809 views

Hello all,

 

currently I am facing next problem - I have STM32H743 with USB configured such as CDC Virtual port COM. Receiving data works very well. But I have a strange problem with sending data. Data I send are not correct received in case of using dynamic array:

sagit_0-1719851862363.png

If I use CDC_Transmit_FS(buffer, 5) are bad data received.

If I use CDC_Transmit_FS((char*)data, 5) all is good.

 

I have checked memory locations and both data pointers in function CDC_Transmit_FS have correct data, but on different memory address.  

I don't have idea why it is so behave. Can anybody help with this? CHATGPT failed, so I try live peoples.

 

sagit_1-1719852285037.png

 

 

sagit_2-1719852427013.png

 

Thank you very much.

    This topic has been closed for replies.

    1 reply

    A
    Andrew Neil
    Super User
    July 1, 2024

    Please don't post code as images - see this for the proper tool:

    https://community.st.com/t5/community-guidelines/how-to-write-your-question-to-maximize-your-chances-to-find-a/ta-p/575228

    Presumably, CDC_Transmit_FS is non-blocking?

    So it's not going to work for sending auto (ie, local non-static) variables - as your buffer.

    When you use 

    char* data[] = "Tesxt";

    You get a pointer to a static location. 

      Terms & ConditionsAccessibility statement