USB Device CDC

[Yash]

Hello,

I'm using Nucleo l4r5zi-p in which I configured the USB device CDC. When I transmit data using the CDC_Transmit_FS function some time it returns USBD_BUSY, sometimes USBD_OK so because of USBD_BUSY I'm not getting actual speed. But I'm transmitting continuous data then why does it return USBD_BUSY?

Thanks,

Yash

[Walid ZRELLI]

Hello @Yash​  ,

It is normal to get the USBD_BUSY status when transmitting data. Could you please provide more details ?

As well, What do you mean by "I'm not getting actual speed" ?

Otherwise, you can refer to the following example : (Path: Projects\STM32L476G-EVAL\Applications\USB_Device\CDC_Standalone )

I hope this help you.

BeST Regards,

Walid

[Yash]

Hello Walid,

As per USB CDC configuration, the actual speed is 12Mbit/sec but we got around 360 microseconds per byte. But it should be 0.6 microseconds if the USB is working on 12Mbit/sec.

Regards,

Yash