307013-003 Datasheet, PDF (181/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

Functional Description
5. After step 4 (power button override), if the user presses the power button again,
the system should wake to an S0 state and the processor should start executing
the BIOS.
6. If step 5 (power button press) is successful in waking the system, the ICH7
continues sending heartbeats until the BIOS clears the SECOND_TO_STS bit. (See
note 2)
7. If step 5 (power button press) is unsuccessful in waking the system, the ICH7
continues sending heartbeats. The ICH7 does not attempt to reboot the system
again until some external intervention occurs (reset, power failure, etc.). (See note
3)
8. After step 3 (third timeout), if a reset is attempted (using a button that pulses
PWROK low or via the message on the SMBus slave I/F), the ICH7 attempts to
reset the system.
9. If step 8 (reset attempt) is successful, the BIOS is run. The ICH7 continues sending
heartbeats until the BIOS clears the SECOND_TO_STS bit. (See note 2)
10. If step 8 (reset attempt), is unsuccessful, the ICH7 continues sending heartbeats.
The ICH7 does not attempt to reboot the system again without external
intervention. Note: A system that has locked up and can not be restarted with
power button press is probably broken (bad power supply, short circuit on some
bus, etc.)
11. This and the following rules/steps apply if the user intervention (power button
press, reset, SMBus message, etc.) occur prior to the third timeout of the watchdog
timer.
12. After step 1 (second timeout), if the user does a Power Button Override, the system
goes to an S5 state. The ICH7 continues sending heartbeats at this point.
13. After step 12 (power button override), if the user presses the power button again,
the system should wake to an S0 state and the processor should start executing
the BIOS.
14. If step 13 (power button press) is successful in waking the system, the ICH7
continues sending heartbeats until the BIOS clears the SECOND_TO_STS bit. (See
note 2)
15. If step 13 (power button press) is unsuccessful in waking the system, the ICH7
continues sending heartbeats. The ICH7 does not attempt to reboot the system
again until some external intervention occurs (reset, power failure, etc.). (See note
3)
16. After step 1 (second timeout), if a reset is attempted (using a button that pulses
PWROK low or via the message on the SMBus slave I/F), the ICH7 attempts to
reset the system.
17. If step 16 (reset attempt) is successful, the BIOS is run. The ICH7 continues
sending heartbeats until the BIOS clears the SECOND_TO_STS bit. (See note 2)
18. If step 16 (reset attempt), is unsuccessful, the ICH7 continues sending heartbeats.
The ICH7 does not attempt to reboot the system again without external
intervention. (See note 3)
If the system is in a G1 (S1–S4) state, the ICH7 sends a heartbeat message every 30–
32 seconds. If an event occurs prior to the system being shutdown, the ICH7
immediately sends an event message with the next incremented sequence number.
After the event message, the ICH7 resumes sending heartbeat messages.
Intel ^® ICH7 Family Datasheet
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