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Mobile Intel
Pentium
4 Processor-M
90
Datasheet
250686-002
The system can generate a STPCLK# while the processor is in the AutoHALT Powerdown state.
When the system deasserts the STPCLK# interrupt, the processor will return execution to the
HALT state.
While in AutoHALT Powerdown state, the processor will process bus snoops.
7.2.3
Stop-Grant State
When the STPCLK# pin is asserted, the Stop-Grant state of the processor is entered 20 bus clocks
after the response phase of the processor issued Stop Grant Acknowledge special bus cycle.
Since the AGTL+ signal pins receive power from the system bus, these pins should not be driven
(allowing the level to return to V
CC
) for minimum power drawn by the termination resistors in this
state. In addition, all other input pins on the system bus should be driven to the inactive state.
BINIT# will not be serviced while the processor is in Stop-Grant state. The event will be latched
and can be serviced by software upon exit from the Stop-Grant state.
RESET# will cause the processor to immediately initialize itself, but the processor will stay in
Stop-Grant state. A transition back to the Normal state will occur with the de-assertion of the
STPCLK# signal. When re-entering the Stop-Grant state from the Sleep state, STPCLK# should
only be de-asserted one or more bus clocks after the de-assertion of SLP#.
A transition to the HALT/Grant Snoop state will occur when the processor detects a snoop on the
system bus (see
Section 7.2.4
). A transition to the Sleep state (see
Section 7.2.5
) will occur with the
assertion of the SLP# signal.
While in the Stop-Grant State, SMI#, INIT#, BINIT# and LINT[1:0] will be latched by the
processor, and only serviced when the processor returns to the Normal State. Only one occurrence
of each event will be recognized upon return to the Normal state.
Figure 35. Clock Control States
snoop
occurs
Stop
Grant
Normal
Sleep
HALT/
Grant
Snoop
Auto Halt
Deep
Sleep
STPCLK# asserted
SLP# asserted
SLP# de-asserted
STPCLK# de-asserted
snoop
serviced
HLT
instruction
ssnoop
occurs
DPSLP#
de-asserted
DPSLP#
asserted
STPCLK#
asserted
STPCLK#
de-asserted
halt
break
V0001-04
core voltage raised
core voltage lowered
Deeper
Sleep
Halt break - A20M#, BINIT#, INIT#, INTR, NMI, PREQ#, RESET#, SMI#, or APIC interrupt