Programmatically determine USB type

[Jason_P]

Hi all,

This is likely one of those really obvious things that I've somehow just missed, but I was wondering if anyone knew of a way to programmatically determine whether a device I'm communicating with is using USB 1.0 or 2.0?  I'm working on a VISA driver for an USB instrument that returns a data set in a completely different format depending on what kind of USB port it is plugged into.  The instrument itself automatically determine which format it will use - and there doesn't appear to be any obvious status/data type indicator I can read off the instrument.  I could pull the data in and analyze it to determine the format, but that seems clumsy.  It would be much better if I could just detect the type and parse the data based on the type...

Any help at all would be appreciated!

Thanks,

Jason

[JTerosky]

I'm currently doing some programming with the FTDI chipset of USB devices.  The FT_GetDeviceInfoList query contains information regarding the speed.  The D2XX_Programmer's Guide descriptions lists: 

The flag value is a 4-byte bit map containing miscellaneous data as defined Appendix A – Type Definitions. Bit 0 (least significant bit) of this number indicates if the port is open (1) or closed (0). Bit 1 indicates if the device is enumerated as a high-speed USB device (2) or a full-speed USB device (0). The remaining bits (2 - 31) are reserved.

I also believe the information is stored in the EEPROM (again, depending upon the chip).  There is a BCD field that is either 0x0110 or 0x0200 depending upon the speed.

Jason

[Jason_P]

Thanks for the reply!  I don't know what chipset my device is using, but it seemed to me this had to be a normal, commonly available function.  After seeing your reply, I went through the datasheet line-by-line (again), and I finally found a reference to a query status command that looks like it might include a byte for USB speed...

Thanks,

Jason