VT82C686B
USB-Specific Configuration Registers
Offset 40 - Miscellaneous Control 1.................................RW
Offset 41 - Miscellaneous Control 2 ................................ RW
7
PCI Memory Command Option
7
USB 1.1 Improvement for EOP
0
Support Memory-Read-Line, Memory-Read-
Multiple, & Memory-Write-&-Invalidate.... def
Only support Mem Read, Mem Write Cmds
0
USB Specification 1.1 Compliant.......... default
If a bit stuffing error occurs before EOP, the
receiver will accept the packet
1
1
USB Specification 1.0 Compliant
6
Babble Option
0
Automatically disable babbled port when EOF
babble occurs..........................................default
If a bit stuffing error occurs before EOP, the
receiver will ignore the packet
1
Don’t disable babbled port
....................default = 0
6-5 Reserved (Do Not Program)
5
4
3
2
1
0
PCI Parity Check Option
4
Hold PCI Request for Successive Accesses
0
Disable PERR# generation.....................default
0
Disable
1
Enable parity check and PERR# generation
1
Enable.................................................... default
Frame Interval Select
Setting this bit to “enable” causes the system to treat
the USB request as higher priority
Frame Counter Test Mode
0
1 ms frame..............................................default
1
0.1 ms frame
3
2
USB Data Length Option
0
Disable................................................... default
0
Support TD length up to 1280................default
1
Enable
1
Support TD length up to 1023
Trap Option
USB Power Management
0
Set trap 60/64 status bits only when trap 60/64
0
Disable USB power management...........default
enable bits are set. ................................. default
Set trap 60/64 status bits without checking
enable bits
1
Enable USB power management
1
DMA Option
0
8 DW burst access with better FIFO latencydef
1
0
A20gate Pass Through Option
1
16 DW burst access (original performance)
0
Pass through A20GATE command sequence
defined in UHCI .................................... default
Don’t pass through Write I/O port 64 (ff)
PCI Wait States
0
Zero wait ................................................default
1
1
One wait
USB IRQ Test Mode
0
Normal Operation.................................. default
1
Generate USB IRQ
Revision 1.71 June 9, 2000
-79-
Function 3 Registers - USB Controller Ports 2-3
ETC [ ETC ]
