I have a USB-device with three interfaces:
- Vendor-Specific Bulk
- CDC Serial Control
- CDC Serial Data
To configure the vendor specific bulk endpoints I need to send vendor specific control requests to endpoint 0. I'm using libusb for this task. As long as the interfaces for the CDC serial port are present I get an access error when trying to send vendor control requests.
If I disable these CDC interfaces I can send vendor control request without any problems:
Is this by design or ist there any possibility to send vendor control requests to the USB device while a CDC driver is active?