Datasheet

 2010 - 2015 Microchip Technology Inc. DS00001692C-page 31
USB251xB/xBi
5.1.31 REGISTER FCH: PORTMAP 34
Bit Number Bit Name Description
7:0 PRTR34 PortMap Register for Ports 3 and 4: 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 4 is disabled
0001 Physical port 4 is mapped to logical port 1
0010 Physical port 4 is mapped to logical port 2
0011 Physical port 4 is mapped to logical port 3
0100 Physical port 4 is mapped to logical port 4
1000
to
1111
rsvd, will default to 0000 value
Bit [3:0]
0000 Physical port 3 is disabled
0001 Physical port 3 is mapped to logical port 1
0010 Physical port 3 is mapped to logical port 2
0011 Physical port 3 is mapped to logical port 3
0100 Physical port 3 is mapped to logical port 4
1000
to
1111
rsvd, will default to 0000 value