Table 5-10. USB Default Configuration Descriptor
Field Description
Length of this Descriptor = 9 bytes
Offset
Value
09H
02H
DAH
00H
01H
01H
0
1
2
3
4
5
bLength
bDescriptorType
wTotalLength (L)
wTotalLength (H)
bNumInterfaces
Descriptor Type = Configuration
Total Length (L) Including Interface and Endpoint Descriptors
Total Length (H)
Number of Interfaces in this Configuration
bConfigurationValue Configuration Value Used by Set_Configuration Request to
Select this Configuration
6
7
8
iConfiguration
bmAttributes
MaxPower
Index of String Describing this Configuration = None
Attributes - Bus-Powered, No Wakeup
Maximum Power - 100 mA
00H
80H
32H
The configuration descriptor includes a total length field (offset 2-3) that encompasses all
interface and endpoint descriptors that follow the configuration descriptor. This configu-
ration describes a single interface (offset 4). The host selects this configuration by issuing
a Set_Configuration requests specifying configuration #1 (offset 5).
Table 5-11. USB Default Interface 0, Alternate Setting 0 Descriptor
Offset
Field
bLength
Description
Length of the Interface Descriptor
Value
09H
04H
00H
00H
00H
FFH
FFH
FFH
00H
0
1
2
3
4
5
6
7
8
bDescriptorType
bInterfaceNumber
bAlternateSetting
bNumEndpoints
bInterfaceClass
Descriptor Type = Interface
Zero-based Index of this Interface = 0
Alternate Setting Value = 0
Number of Endpoints in this Interface (Not Counting EPO) = 0
Interface Class = Vendor Specific
bInterfaceSubClass Interface Sub-class = Vendor Specific
bInterfaceProtocol
iInterface
Interface Protocol = Vendor Specific
Index to String Descriptor for this Interface = None
Interface 0, alternate setting 0 describes endpoint 0 only. This is a zero bandwidth setting.
The interface has no string index.
Page 5-14
Chapter 5. EZ-USB CPU
EZ-USB TRM v1.9
CYPRESS [ CYPRESS ]
