ACPI REGISTERS
In the FDC37B78x, the PME wakeup events can be enabled as SCI events through the SCI_STS1 and
SCI_EN1 bits in the GPE status and enable registers. See PME Interface and SMI/PME/SCI logic
sections.
Power Management 1 Status Register 1 (PM1_STS 1)
Register Location: <PM1_BLK> System I/O Space
Default Value:00h on Vbat POR
Attribute:Read/Write (Note 0)
Size:8-bits
BIT
0-7
NAME
Reserved
DESCRIPTION
Reserved. These bits always return a value of zero.
Note 0: All bits described as "reserved" in writeable registers must be written with the value 0 when the
register is written.
Note 1: This bit is set by hardware and can only be cleared by software writing a one to this bit position
and by Vbat POR. Writing a 0 has no effect.
Power Management 1 Status Register 2 (PM1_STS 2)
Register Location: <PM1_BLK>+1h System I/O Space
Default Value:00h on Vbat POR
Attribute:Read/Write (Note 0)
Size:8-bits
BIT
NAME
DESCRIPTION
0
PWRBTN_STS
This bit is set when the Button_In signal is asserted. In the system
working state, while PWRBTN_EN and PWRBTN_STS are both set
an SCI interrupt event is raised. In the sleeping or soft off state, a
wake-up event is generated (regardless of the setting of
PWRBTN_EN) (Note 2). This bit is only set by hardware and is reset
by software writing a one to this bit position, and by Vbat POR.
Writing a 0 has no effect. It is also reset as follows: If
PWRBTNOR_EN is set, and if the Button_In signal is held asserted
for more than four seconds, then this bit is cleared, the
PWRBTNOR_STS bit is set and the system will transition into the
soft off state (nPowerOn floats).
1
2
Reserved
RTC_STS
Reserved.
This bit is set when the RTC generates an alarm. Additionally if the
RTC_EN bit is set then the setting of the RTC_STS bit will generate
an SCI. When the AL_REM_EN bit is set in the RTC control register
1, then the RTC_STS bit is set due to an RTC alarm event occurring
when Vtr is not present. This will indicate to the OS the cause of the
wakeup event (nPowerOn pin asserted when Vtr returns) caused by
the “alarm remember” logic in the Soft Power Management block.
(Note 1)
3
PWRBTNOR_STS
This bit is set when the power switch over-ride function is set: If
PWRBTNOR_EN is set, and if the Button_In signal is held asserted
for more than four seconds. Hardware is also required to reset the
PWRBTN_STS when issuing a power switch over-ride function.
157
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