Datasheet

USB 2.0 Hi-Speed 7-Port Hub Controller
Datasheet
SMSC USB2517 31 Revision 2.8 (09-17-12)
DATASHEET
7.2.1.29 Register FAh: Port Swap
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= ’1’; Port 7 DP/DM is swapped.
Bit 6= ’1’; Port 6 DP/DM is swapped.
Bit 5= ’1’; Port 5 DP/DM is swapped.
Bit 4= ‘1’; Port 4 DP/DM is swapped.
Bit 3= ‘1’; Port 3 DP/DM is swapped.
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