USB 2.0 Hi-Speed Hub Controller

Datasheet

 

 

 

8.2.1.29

Register F8h: Boost_4:0

 

 

 

 

BIT

 

 

 

NUMBER

BIT NAME

 

DESCRIPTION

 

 

 

 

7:6

BOOST_IOUT_4

 

USB electrical signaling drive strength Boost Bit for Downstream Port ‘4’.

 

 

 

‘00’ = Normal electrical drive strength = No boost

 

 

 

‘01’ = Elevated electrical drive strength = Low (~4% boost)

 

 

 

‘10’ = Elevated electrical drive strength = Medium (~ 8% boost)

 

 

 

‘11’ = Elevated electrical drive strength = High (~12% boost)

 

 

 

 

5:4

BOOST_IOUT_3

 

USB electrical signaling drive strength Boost Bit for Downstream Port ‘3’.

 

 

 

‘00’ = Normal electrical drive strength = No boost

 

 

 

‘01’ = Elevated electrical drive strength = Low (~4% boost)

 

 

 

‘10’ = Elevated electrical drive strength = Medium (~ 8% boost)

 

 

 

‘11’ = Elevated electrical drive strength = High (~12% boost)

 

 

 

 

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 (~4% boost)

 

 

 

‘10’ = Elevated electrical drive strength = Medium (~ 8% boost)

 

 

 

‘11’ = Elevated electrical drive strength = High (~12% boost)

 

 

 

 

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 (~4% boost)

 

 

 

‘10’ = Elevated electrical drive strength = Medium (~ 8% boost)

 

 

 

‘11’ = Elevated electrical drive strength = High (~12% boost)

 

 

 

 

Note: “Boost” could result in non-USB Compliant parameters, OEM should use a ‘00’ value unless

 

specific implementation issues require additional signal boosting to correct for degraded USB

 

signalling levels.

 

8.2.1.30Register FAh: Port Swap

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= Controls Port 7

 

 

Bit 6= Controls Port 6

 

 

Bit 5= Controls Port 5

 

 

Bit 4= Controls Port 4

 

 

Bit 3= Controls Port 3

 

 

Bit 2= Controls Port 2

 

 

Bit 1= Controls Port 1

 

 

Bit 0= When this bit is ‘1’, the upstream port DP/DM is swapped.

 

 

 

SMSC USB251x

47

Revision 1.0 (3-11-09)

DATASHEET