82NM10 Datasheet, PDF (459/671 Pages) Intel Corporation – Intel® NM10 Family Express Chipset

UHCI Controllers Registers
Table 14-133.USB I/O Registers
BASE +
Offset
Mnemonic
Register Name
00–01h
02–03h
04–05h
06–07h
08–0Bh
0Ch
0D–0Fh
10–11h
USBCMD
USBSTS
USBINTR
FRNUM
FRBASEADD
SOFMOD
—
PORTSC0
USB Command
USB Status
USB Interrupt Enable
Frame Number
Frame List Base Address
Start of Frame Modify
Reserved
Port 0 Status/Control
12–13h PORTSC1 Port 1 Status/Control
Default
Type
0000h
0020h
0000h
0000h
Undefined
40h
—
0080h
0080h
R/W
R/WC
R/W
R/W (see Note 1)
R/W
R/W
—
R/WC, RO, R/W
(see Note 1)
R/WC, RO, R/W
(see Note 1)
NOTES:
1.
These registers are WORD writable only. Byte writes to these registers have unpredictable
effects.
14.2.1
USBCMD—USB Command Register
I/O Offset:
Base + (00h–01h)Attribute:R/W
Default Value:
0000hSize:16 bits
The Command Register indicates the command to be executed by the serial bus host
controller. Writing to the register causes a command to be executed. The table
following the bit description provides additional information on the operation of the
Run/Stop and Debug bits.
Bit
Description
15:7
8
7
Reserved
Loop Back Test Mode — R/W.
0 = Disable loop back test mode.
1 = Chipset is in loop back test mode. When both ports are connected together, a write
to one port will be seen on the other port and the data will be stored in I/O offset
18h.
Max Packet (MAXP) — R/W. This bit selects the maximum packet size that can be
used for full speed bandwidth reclamation at the end of a frame. This value is used by
the host controller to determine whether it should initiate another transaction based on
the time remaining in the SOF counter. Use of reclamation packets larger than the
programmed size will cause a Babble error if executed during the critical window at
frame end. The Babble error results in the offending endpoint being stalled. Software is
responsible for ensuring that any packet which could be executed under bandwidth
reclamation be within this size limit.
0 = 32 bytes
1 = 64 bytes
Datasheet
459