When CYUSB3014 is configured host mode ,USB flash drives can''t enumerates! There is always timeout when the enumeration is go to read the full device descriptor.the firware code is supplied by FX3 SDK.if I try more times ,the USB flash drives's fireware will be damaged and plugged into computer,there is a information "can't find disc drive"when double clike it.

      However, it  worked when CYUSB3014 is configured host mode enumerate USB flash drives few months ago,and the fireware code is same in FX3 SDK. how can I solve the problem?

Are you using the latest SDK?.

Did you notice the below mentioned details in the source code:

"Care should be taken so that an USB host is not connected to FX3 while
   host stack is active. This will mean that both sides will be driving
   the VBUS causing a hardware damage.

   Please refer to the FX3 DVK user manual for enabling VBUS control.
   The current example controls the VBUS supply via GPIO 21. The example assumes
   that a low on this line will turn on VBUS and allow remotely connected B-device
   to enumerate. A high / tri-state  on this line will turn off VBUS supply from
   the board. Also this requires that FX3 DVK is powered using external power supply.
   VBATT should also be enabled and connected. Depending upon the VBUS control,
   update the CY_FX_OTG_VBUS_ENABLE_VALUE and CY_FX_OTG_VBUS_DISABLE_VALUE definitions
   in cyfxusbhost.h file."

Please let me know if you are following all of these.

Thanks,

sai krishna.

       I am using the latest SDK 1.1 and not use the Official DVK.The device I use is powered by external power supply and not use VBUS power device .