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USB 2.0 Hi-Speed 2-Port Hub Controller
Datasheet
Revision 1.96 (07-11-08) 22 SMSC USB2512A
DATASHEET
4.2.1.20 Register FAh: Port Swap
3:2 BOOST_IOUT_2 USB electrical signaling drive strength Boost Bit for Downstream Port ‘2’.
‘00’ = Normal electrical drive strength = No boost
‘01’ = Elevated electrical drive strength = Low (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note: “Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), the OEM should use a 00 value
unless specific implementation issues require additional signal
boosting to correct for degraded USB signalling levels.
1:0 BOOST_IOUT_1 USB electrical signaling drive strength Boost Bit for Downstream Port ‘1’.
‘00’ = Normal electrical drive strength = No boost
‘01’ = Elevated electrical drive strength = Low (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note: “Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), the OEM should use a 00 value
unless specific implementation issues require additional signal
boosting to correct for degraded USB signalling levels.
BIT
NUMBER BIT NAME DESCRIPTION
7:0 PRTSP Port Swap: Swaps the Upstream and Downstream USB DP and DM Pins for
ease of board routing to devices and connectors.
‘0’ = USB D+ functionality is associated with the DP pin and D- functionality
is associated with the DM pin.
‘1’ = USB D+ functionality is associated with the DM pin and D- functionality
is associated with the DP pin.
Bit 7= Reserved
Bit 6= Reserved
Bit 5= Reserved
Bit 4= Reserved
Bit 3= Reserved
Bit 2= ‘1’; Port 2 DP/DM is Swapped.
Bit 1= ‘1’: Port 1 DP/DM is Swapped.
Bit 0= ‘1’:Upstream Port DP/DM is Swapped
BIT
NUMBER BIT NAME DESCRIPTION