AnsweredAssumed Answered

STM32F4 USB composite MSD problem

Question asked by kumar.rachit.001 on Mar 18, 2015
Latest reply on Mar 23, 2015 by kumar.rachit.001

I have  a product which works as a USB composite device (CDC + MSD). This same product was previously designed to work only as a MSD device, without composite functionality.
The device with composite funtionality has a different product ID as to when it was being previously used only as MSD.
For the composite functionality, the device parameters are,
Class EF, Subclass 02 and Device protocol 01.
The requirement is that this new device should atleast work as a Mss Storage Device even when no driver to use the COM port is installed, i.e, in case the user does not require the CDC class, he/she need not install the driver provided by us, as for MSD, it should simply use the usbstor driver provided by Windows.
The problem I am facing is that on most PC's (Windows 7, 64 bit), the device works without any problem but on some, Windows does not report that it encountered a problem and in the Device Manager list, the USB Mass Storage device is listed with a yellow ! mark, indicating it encountered a problem. The error code is 10. Even more interesting is that if the driver is updated once, it is properly recognised and works without problem, even when the driver is exactly the same as before.
The only difference I observed is the way the Hardware ID is listed. For the case where it has a problem, the Device ID is represented in the format /Vendor ID/Product ID.
After updating, it is listed as /Vendor ID/Product ID/Interface number.
So I suspect somehow Windows does not enumerate the Interface correctly.

Can anybody clarify if you have encountered similar problem or some idea in which direction I should investigate this issue further?

I am attaching the screenshots for both cases, i.e, before updating the driver and after.

Any kind of help will be highly appreciated.