I want to use the usb interface of SL6087 . But I met some question. The host PC: Windows 7 64 bit . When I plug the usb connector to PC.Windows told me that "Unkown Device".it have not install driver this time.and i check the hardward id. it is null. i tested it under windows xp 32bit. it is same. the SL6087 's firmware: 126.96.36.199205311751 I have already check: 1:VPAD_USB :3.3V . 2:VBAT: 3.8V 3: SL6087 works well by com port. 4: USB port is enabled. Please tell me how can i check more.very thanks!