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RKUMA.2
RKUMA.2
Associate III
May 15, 2021
Question

why the stm32usb_cdc entering into DFU mode when I connected with pc

  • May 15, 2021
  • 3 replies
  • 3357 views

Hello,

I am working on the stm32f070c6 ,I wrote the code for usb_cdc , when I was connected with pc it was either showing as DFU mode or STM32 boot loader, it is not detected as COM port . why it is entering into DFU mode how to overcome and how it will detect as COM port , the code and everything is okay(no errors )

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3 replies

Tesla DeLorean
Tesla DeLorean
Guru
May 15, 2021

BOOT0 is HIGH, or the part is blank? ​

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RKUMA.2
RKUMA.2Author
Associate III
May 15, 2021

Thanks for your reply @Community member​ , when I uploading the program boot0 pin connected to high, if I disconnect the boot0 pin from vcc , it shows as usb device descriptor request failed, if i make boot0 pin to high , it is showing as in device manager window either DFU MODE/ stm32 bootloader. it is not detected as COM port

Tesla DeLorean
Tesla DeLorean
Guru
May 15, 2021

So a code/implementation issue on the CDC​

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RKUMA.2
RKUMA.2Author
Associate III
May 15, 2021

@Community member​  The code is correct because I took the reference from the st website

TDK
TDK
Super User
May 15, 2021

When BOOT0 is high, it enters the system bootloader (DFU mode).

As for why it's not working in CDC mode with your code, probably a firmware issue.

> the code and everything is okay(no errors )

You mean no errors when compiling? Hardly means the code is okay.

At least since it enters DFU mode, you can rule out any hardware issues related to the USB lines.

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