isp1520 NXP Semiconductors, isp1520 Datasheet - Page 21

• Manufacturer Part Number: isp1520
• Description: Hi-speed Universal Serial Bus Hub Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9. Hub controller description
ISP1520_4
Product data sheet
9.1 Endpoint 0
9.2 Endpoint 1
Each USB device is composed of several independent logic endpoints. An endpoint acts
as a terminus of communication flow between the host and the device. At design time,
each endpoint is assigned a unique number (endpoint identifier; see
combination of the device address (given by the host during enumeration), the endpoint
number, and the transfer direction allows each endpoint to be uniquely referenced.
The ISP1520 has two endpoints: endpoint 0 (control) and endpoint 1 (interrupt).
Table 13.
[1]
According to the USB specification, all devices must implement a default control endpoint.
This endpoint is used by the host to configure the USB device. It provides access to the
device configuration and allows generic USB status and control access.
The ISP1520 supports the following descriptor information through its control endpoint 0:
The maximum packet size of this endpoint is 64 B.
Endpoint 1 can be accessed only after the hub has been configured by the host (by
sending the Set Configuration command). It is used by the ISP1520 to send the status
change information to the host.
Endpoint 1 is an interrupt endpoint. The host polls this endpoint once every 255 ms. After
the hub is configured, an IN token is sent by the host to request the port change status. If
the hub detects no change in the port status, it returns a NAK to this request, otherwise
the Status Change byte is sent.
Function
Hub ports 0 to 4
•
•
•
•
•
•
•
IN: input for the USB host; OUT: output from the USB host.
Device descriptor
Device_qualifier descriptor
Configuration descriptor
Interface descriptor
Endpoint descriptor
Hub descriptor
Other_speed_configuration descriptor
Hub endpoints
Endpoint
identifier
0
1
Rev. 04 — 28 April 2006
Table 14
Transfer type
control
interrupt
shows the content of the change byte.
Direction
OUT
IN
IN
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Hi-Speed USB hub controller
[1]
Table
Maximum packet
size (bytes)
64
64
1
ISP1520
13). The
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