
EZ-USB FX2 Technical Reference Manual
A - 2 EZ-USB FX2 Technical Reference Manual v2.1
The configuration descriptor includes a total length field (offset 2-3) that encompasses all interface
and endpoint descriptors that follow the configuration descriptor. This configuration describes a
single interface (offset 4). The host selects this configuration by issuing a Set_Configuration
requests specifying configuration #1 (offset 5).
Table A-2 Device Qualifier
Offset Field Description Value
0 bLength Length of this Descriptor = 10 bytes 0AH
1 bDescriptorType
Descriptor Type =
Device Qualifier
06H
2 bcdUSB (L) USB Specification Version 2.00 (L) 00H
3 bcdUSB (H) USB Specification Version 2.00 (H) 02H
4 bDeviceClass Device Class (FF is Vendor-Specific) FFH
5 bDeviceSubClass Device Sub-class (FF is Vendor-Specific) FFH
6 bDeviceProtocol Device Protocol (FF is Vendor-Specific) FFH
7 bMaxPacketSize0
Maximum Packet Size for other speed =
64 bytes
40H
8 bNumConfigurations Number of other Configurations = 1 01H
9 bReserved Must be set to zero 00H
Table A-3 USB Default Configuration Descriptor
Offset Field Description Value
0 bLength Length of this Descriptor = 9 bytes 09H
1 bDescriptorType Descriptor Type = Configuration 02H
2 wTotalLength (L) Total Length (L) Including Interface and Endpoint Descriptors
(171 total)
ABH
3 wTotalLength (H) Total Length (H) 00H
4 bNumInterfaces Number of Interfaces in this Configuration 01H
5 bConfigurationValue Configuration Value Used by Set_Configuration Request to
Select this interface
01H
6 iConfiguration Index of String Describing this Configuration = None 00H
7 bmAttributes Attributes - Bus-Powered, No Wakeup 80H
8 MaxPower Maximum Power - 100 mA 32H
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