Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 2.2 (02-17-12) 40 SMSC USB251xB/xBi
DATASHEET
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 32) 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