[Nexus 7 Q&A, Help & Troubleshooting] bftb0:
(Note I attached some pictures below)

From the Device Manager:

- Select the Device in question by right-clicking. Choose "Properties"

- A window with three tabs will appear: General, Driver, and Details. Select Details

- The "Property" combo-box-selector has 20 or 30 items - the 2nd one in the list is Hardware Ids. I attached two pictures from Win7-Pro-x64 (below)

But note as I said before: You should NOT be seeing the ADB endpoint under "Portable Devices" - if ADB Debugging is turned on in the OS, you should see it under "Android Phone" or something similar. In any event, the hardware Ids will identify it exactly

Well, as far as the behavior of the USB driver on the PC, almost nothing. Unfortunately - for better or for worse - both TeamWin (TWRP) and CWM authors put their ADB interface on the bus with the VID/PID pair of USB\VID_18D1&PID_D001, whereas the OS puts all its USB interfaces on 18D1/4Exx.

So, even if you get a driver installed for the OS "adb" mode (say by using the Google SDK USB driver or the Asus Nexus 7 driver), it won't work for the custom recovery... unless you fix up the driver installer package to have the matching VID/PID pairs (18D1/D001) in the .INF file for that driver.

I think folks find this confusing - they think, "wait, I have a ADB driver installed" - why does it not work?

OK, there are a couple more things to try (at least before I give up). Roughly they try to answer these questions:

Q1) Is this a toolkit issue, or a driver issue?

Q2) Is it a prior driver you installed that you are not observing that is causing the problem?

The first one (Q1) is easiest to diagnose: when your PC Device Manager indicates that a device is "working normally" - AND THE VID/PID ID MATCHES WHAT YOU SHOULD EXPECT FOR THE MODE THE TABLET IS IN (regular OS, recovery boot, fastboot mode), can you communicate with the device from the Windows command line? e.g.,

C:\foo> cd C:\blahblah\sdk-platform-tools-directory
C:\blahblah\sdk-platform-tools-directory> fastboot devices
or
C:\blahblah\sdk-platform-tools-directory> adb devices

If you can communicate with the tablet from the command line - your device ID will be printed by the above commands, then you don't have a driver problem at all - there is something screwy about the way your toolkit is installed.

OK, Q2 -

When Windows installs a driver, it caches it into a kind of database. I suppose it is possible that a prior driver installation might be causing trouble. You can observe - from the device manager - all the drivers that are installed - even for devices that are not currently connected to your computer.

This is done by setting the "devmgr_show_nonpresent_devices=1" environment variable. It can be done semi-permanently this way, or for a single invocation of the device manager this way..

See the third image attached (devmgr-all-devices.jpg ) - it is my computer in that "show all devices" mode. See all that rubbish in there? It's from other Android devices (HTC, Samsung, etc).

You can walk through each one of those - even the devices that are not currently attached - and inspect the VID/PID pair to see if they happen to match the values that you are expecting to see for the different operating modes on the Nexus 7. I'll leave it up to you whether you want to do this or not; it is a bit tedious. Just don't start deleting drivers willy-nilly if you don't know what they are associated with.

I am understanding everything you are saying - and your english is far better than my italian :)

good luck!