CX11627 Datasheet, PDF (49/56 Pages) Conexant Systems, Inc – AccessRunner ADSL-USB Modem Device Set

AccessRunner ADSL-USB Modem Device Set Data Sheet
4.1.4 Endpoint Descriptor
Each endpoint used for an interface has its own descriptor, which contains the information required by the host to determine
the bandwidth requirements of each endpoint (see Table 4-4). An endpoint descriptor, like an Interface Descriptor, is always
returned as part of a configuration descriptor. The default values are:
Bulk In 1: 07058102400000
Bulk Out 1: 07050102400000
Bulk In 2: 07058202400000
Bulk Out 2: 07050202400000
Bulk In 3: 07058302400000
Bulk Out 3:
Bulk In 4:
Bulk Out 4:
07050302400000
07058402400000
07050402400000
Table 4-4. Endpoint Descriptors
Offset
0
1
2
Field
bLength
bDescriptorType
bEndpointAddress
3
bmAttributes
4
wMaxPacketSize
6
bInterval
Size
1
1
1
1
2
1
Value
Number
Constant
Endpoint
Bit Map
Number
Number
Description
Size of this descriptor in bytes.
ENDPOINT Descriptor Type.
The address of the endpoint on the USB device described by this
descriptor. The address is encoded as follows:
Bit 0..3: The endpoint number
Bit 4..6: Reserved, reset to 0
Bit 7: Direction, ignored for control endpoints
0 OUT endpoint
1 IN endpoint
This field describes the endpoint’s attributes when it is configured
using the bConfigurationValue.
Bit 0..1: Transfer Type
00 Control
01 Isochronous
10 Bulk
11 Interrupt
All other bits are reserved
Maximum packet size this endpoint is capable of sending or receiving
when this configuration is selected.
For isochronous endpoints, this value is used to reserve the bus time
in the schedule, required for the per frame data payloads. The pipe
may, on an ongoing basis, actually use less bandwidth than that
reserved. The device reports, if necessary, the actual bandwidth used
via its normal, non-USB defined mechanisms.
For interrupt, bulk, and control endpoints smaller data payloads may
be sent, but will terminate the transfer and may or may not require
intervention to restart. Refer to Chapter 5 for more information.
Interval for polling endpoint for data transfers. Expressed in
milliseconds.
This field is ignored for bulk and control endpoints. For isochronous
endpoints this field must be set to 1. For interrupt endpoints, this field
may range from 1 to 255.
100427B
Conexant
4-5