82801BA Datasheet, PDF (317/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

LPC Interface Bridge Registers (D31:F0)
Bit
Description
Software SMI Rate Select (SWSMI_RATE_SEL)—R/W.
10 _{0 = SWSMI Timer will time out in 64 ms ± 4 ms (default).}
1 = SWSMI Timer will time out in 1.5 ms ± 0.5 ms.
PWRBTN# Level (PWRBTN_LVL)—RO. This read-only bit indicates the current state of the
PWRBTN# signal.
9
0 = Low.
1 = High.
8:7 Reserved.
iiA64 Processor Mode Enable (A64_EN)—R/W. Set by software to indicate the presence of an
iA64 processor.
6
0 = iA32 processor mode.
1 = iA64 processor mode.
CPU SLP# Enable (CPUSLP_EN)—R/W.
0 = Disable..
ICH2 (82801BA):
1 = Enables the CPUSLP# signal to go active in the S1 state. This reduces the processor power.
5 Note that CPUSLP# will go active on entry to S3, S4 and S5 even if this bit is not set.
ICH2-M (82801BAM):
1 = Enables the CPUSLP# signal to go active in the C3 state. This reduces the processor power.
Note that CPUSLP# goes active during SpeedStep™ transitions and on entry to S1, S3, S4 and
S5 even if this bit is not set.
4 Reserved.
ICH2 (82801BA):
Reserved
ICH2-M (82801BAM):
3
Intel^® SpeedStep^™ Enable (SS_EN)— R/W.
0 = Intel^® SpeedStep^™ logic is disabled and the SS_CNT register will not be visible (reads to
SS_CNT return 00h and writes have no effect).
1 = Intel^® SpeedStep^™ logic is enabled.
ICH2 (82801BA):
Reserved
ICH2-M (82801BAM):
PCI CLKRUN# Enable (CLKRUN_EN)— R/W.
2 0 = Disable. ICH2-M drives the CLKRUN# signal low.
1 = Enable CLKRUN# logic to control the system PCI clock via the CLKRUN# and STP_PCI#
signals.
Note that when the SLP_EN# bit is set, the ICH2-M drives the CLKRUN# signal low, regardless of
the state of the CLKRUN_EN bit. This ensures that the PCI and LPC clocks continue running during
a transition to a sleep state.
Periodic SMI# rate Select (PER_SMI_SEL)—R/W. Set by software to control the rate at which
periodic SMI# is generated.
00 = 1 minute
1:0 _{01 = 32 seconds}
10 = 16 seconds
11 = 8 seconds
82801BA ICH2 and 82801BAM ICH2-M Datasheet
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