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High Speed Inter-Chip USB 2.0 Hub and Flash Media Controller
Datasheet
Revision 1.0 (06-01-09) 48 SMSC USB4640/USB4640i
DATASHEET
8.4.4.21 F2h: Port Map 12
BIT BYTE NAME DESCRIPTION
7:0 PRTM12 PortMap register for ports 1 & 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 reported having.
The host's port number is referred to as “logical port number” and the
physical port on the hub is the “physical port number”. When remapping
mode is enabled (see PRTMAP_EN in Register 08h: Configuration Data
Byte 3) the hub's downstream port numbers can be remapped to different
logical port numbers (assigned by the host).
Note: The OEM must ensure that contiguous logical port numbers are
used, 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.
Table 8.5 Port Map Register for Ports 1 & 2
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’
to
‘1111’
Illegal; Do not use
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’
to
‘1111’
Illegal; Do not use