USB251 datasheet(30/57 Pages) MICROCHIP

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USB251xB/xBi

DS00001692C-page 30

 2010 - 2015 Microchip Technology Inc.

5.1.30

Bit Number

Bit Name

Description

7:0

PRTR12

PortMap Register for Ports 1 and 2: When a hub is enumerated by a USB

host controller, the hub is only permitted to report how many ports it has; the

hub is not permitted to select a numerical range or assignment. The host

controller will number the downstream ports of the hub starting with the

number 1, up to the number of ports that the hub reports having.

The host's port number is called the Logical Port Number and the physical

port on the hub is the Physical Port Number. When mapping mode is enabled

(see PRTMAP_EN, Section 5.1.9 on page 23) the hub's downstream port

numbers can be mapped to different logical port numbers (assigned by the

host).

Note:

Contiguous logical port numbers must be implemented, starting from

number 1 up to the maximum number of enabled ports. This ensures

that the hub's ports are numbered in accordance with the way a host

will communicate with the ports.

Bit [7:4]

0000

Physical port 2 is disabled

0001

Physical port 2 is mapped to logical port 1

0010

Physical port 2 is mapped to logical port 2

0011

Physical port 2 is mapped to logical port 3

0100

Physical port 2 is mapped to logical port 4

1000

1111

rsvd, will default to 0000 value

Bit [3:0]

0000

Physical port 1 is disabled

0001

Physical port 1 is mapped to logical port 1

0010

Physical port 1 is mapped to logical port 2

0011

Physical port 1 is mapped to logical port 3

0100

Physical port 1 is mapped to logical port 4

1000

1111

rsvd, will default to 0000 value

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