isp1122 NXP Semiconductors, isp1122 Datasheet - Page 11

• Manufacturer Part Number: isp1122
• Description: Isp1122 Universal Serial Bus Stand-alone Hub
• Manufacturer: NXP Semiconductors

8. Endpoint descriptions
Philips Semiconductors
9397 750 07002
Product specification
8.1 Hub endpoint 0 (control)
8.2 Hub endpoint 1 (interrupt)
Each USB device is logically composed of several independent endpoints. An
endpoint acts as a terminus of a communication flow between the host and the
device. At design time each endpoint is assigned a unique number (endpoint
identifier, see
during enumeration), the endpoint number and the transfer direction allows each
endpoint to be uniquely referenced.
The ISP1122 has two endpoints, endpoint 0 (control) and endpoint 1 (interrupt).
Table 5:
[1]
All USB devices and functions must implement a default control endpoint (ID = 0).
This endpoint is used by the host to configure the device and to perform generic USB
status and control access.
The ISP1122 hub supports the following USB descriptor information through its
control endpoint 0, which can handle transfers of 64 bytes maximum:
Endpoint 1 is used by the ISP1122 hub to provide status change information to the
host. This endpoint can be accessed only after the hub has been configured by the
host (by sending the Set Configuration command).
Endpoint 1 is an interrupt endpoint: the host polls it once every 255 ms by sending an
IN token. If the hub has detected no change in the port status it returns a NAK (Not
AcKnowledge) response to this request, otherwise it sends the Status Change byte
(see
Function
Hub
•
•
•
•
•
•
Device descriptor
Configuration descriptor
Interface descriptor
Endpoint descriptor
Hub descriptor
String descriptor.
IN: input for the USB host; OUT: output from the USB host.
Table
Hub endpoints
6).
Ports
0: upstream
1 to 5: downstream
Table
Rev. 03 — 29 March 2000
5). The combination of the device address (given by the host
Endpoint
identifier
0
1
Transfer
type
control
interrupt
Direction
OUT
IN
IN
USB stand-alone hub
© Philips Electronics N.V. 2000. All rights reserved.
ISP1122
[1]
Max. packet
size (bytes)
64
64
1
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