The Function CDC_Transmit_FS() => always return USBD_BUSY state.

[VRajk.1]

Hai,

I'm using stm32f070c6 controller for USB CDC application ,I tried to debug the USB CDC Communication., The Function CDC_Transmit_FS() => always return USBD_BUSY state. Need to Find the overcome of USBD_BUSY state. and it shows unknown device(device descriptor request failed), I have increased the heap size ,and i have connected 1.5k resistor between the vbus and d+ ,i have checked the respected pins voltages vbus-5v,d+ =3.1v,I have shifted to different IDE "S but no use ,please if you have any idea about of this problem please give a suggestion how to overcome this error, why the CDC_TRANSMIT function always return usbd_busy, I have tried with different ways but no use, I'm sharing the image

[Imen.D]

Hello @VRajk.1​,

I am checking this issue and I will come back to you with update.

Imen

[Pavel A.]

@VRajk.1​ 

> it shows unknown device(device descriptor request failed)

Focus on finding why the descriptor request fails.

USB device can send only when the host asks it to do so. Until then, you will see USBD_BUSY.

To "overcome" this the device must pass enumeration successfully.

-- pa

[RKUMA.2]

Thanks for your reply @Pavel A.​ , actually I am trying to finding the why the device descriptor request failed , I have done with so many things from st community forum but still it is same, I didn't understand where I am stucked , is there any alternative suggestions to overcome this problem

[Pavel A.]

It's time to get a USB bus analyzer.

[Imen.D]

Hi @RKUMA.2​ ,

From your shared code in this post, it is clear that you missed to add set and get coding lines which are required.

Please refer to provided code in STM32CubeF0 CDC interface file:

\Projects\STM32072B_EVAL\Applications\USB_Device\CDC_Standalone\Src\usbd_cdc_interface.c

Please, keep me informed about your progress on this issue.

Imen

[Pavel A.]

> it is clear that you missed to add set and get coding lines which are required.

But this cannot cause " unknown device(device descriptor request failed)"

--pa