SMSC LAN9514 - Manual (Page 32)

USB Hub with Integrated 10/100 Ethernet Controller
Datasheet
Revision 1.0 (04-20-09) 32 SMSC LAN9514
DATASHEET
Table 3.9 Boost_4:2 Register (BOOST42) Format
BITS DESCRIPTION DEFAULT
7:6 Upstream USB Electrical Signaling Drive Strength Boost Bit for
Downstream Port 4 (BOOST_IOUT_4)
00 = Normal electrical drive strength
01 = Elevated electrical drive strength (+4% boost)
10 = Elevated electrical drive strength (+8% boost)
11 = Elevated electrical drive strength (+12% boost)
00b
5:4 Upstream USB Electrical Signaling Drive Strength Boost Bit for
Downstream Port 3 (BOOST_IOUT_3)
00 = Normal electrical drive strength
01 = Elevated electrical drive strength (+4% boost)
10 = Elevated electrical drive strength (+8% boost)
11 = Elevated electrical drive strength (+12% boost)
00b
3:2 Upstream USB Electrical Signaling Drive Strength Boost Bit for
Downstream Port 2 (BOOST_IOUT_2)
00 = Normal electrical drive strength
01 = Elevated electrical drive strength (+4% boost)
10 = Elevated electrical drive strength (+8% boost)
11 = Elevated electrical drive strength (+12% boost)
00b
1:0 RESERVED 00b
Table 3.10 Status/Command Register (STCD) Format
BITS DESCRIPTION DEFAULT
7:2 RESERVED 000000b
1 Reset (RESET)
Resets the internal memory back to nRESET assertion default settings.
0 = Normal Run/Idle State
1 = Force a reset of the registers to their default state
Note:
During this reset, this bit is automatically cleared to its default value
of 0.
0b
0 USB Attach and Write Protect (USB_ATTACH)
0 = Device is in configuration state
1 = Hub will signal a USB attach event to an upstream device, and the
internal memory (address range 00h - FEh) is “write-protected” to prevent
unintentional data corruption.
Note:
This bit is write once and is only cleared by assertion of the external
nRESET or POR.
1b