
9.0 System Wake-Up Control (SWC)
(Continued)
Revision 1.2
171
www.national.com
P
In addition, a wake-up mechanism can be enabled to trigger a 100 ms pulse at the PWBTOUT output on each valid wake-
up event. This wake-up mechanism is routed to the PWBTOUT pulse generator only if the PWBTOUT_MODE bit in the
ACPI_CFG register (see Section 9.3.32 on page 201) is reset.
The PWBTOUT wake-up mechanism is similar to the one described for the ONCTL signal, as follows:
G
It is based on status bits in the GPE1_STS_0 to GPE1_STS_3 registers and in the PM1b_STS_HIGH register (ex-
cept the PWBT_EVT_STS and the PWRBTN_STS bits).
G
It is not affected by the Watchdog Status bit (WDO_EVT_STS).
G
It is independent of the enable bits in the GPE1_EN_0 to GPE1_EN_3 registers and in the PM1b_EN_HIGH register.
G
It is dependent only on the S3I and S45 current sleep states.
G
Its configuration bits are also located in the WK_ST_EN register, which is accessed by writing the event index value
into the WKUPSEL field of the WK_EVT_SEL register.
The PWBT_EN_S3I and PWBT_EN_S45 bits control the generation of a wake-up pulse on PWBTOUT by an active event
(currently accessed through the WK_EVT_SEL register) when the PC8741x device is in S3I or in S45 current state, respec-
tively.
Any valid wake-up event is disabled from generating a wake-up pulse on PWBTOUT for 1 second after the power supply
has been turned off (by setting ONCTL = 1). If the Keyboard/Mouse Power Control feature (VDDFELL) is enabled by setting
the VDDFLMUX bit to ‘1’ (in the SIOCF2 register; see Section 3.7.3 on page 50), the Keyboard and Mouse wake-up events
are disabled from generating a wake-up pulse for 2 seconds after the power supply has been turned off (by setting ONCTL
= 1).
A PWBTOUT pulse is generated only when the V
DD
power is not present or when a PWBTIN pulse occurred.
Figure 51. PWBTOUT Control
GPE1_STS_0-3
Status
Set
PWBTOUT
State S3I
From Other
Enabled Events
State S45
PWBT_
EN_S45
PWBT_
EN_S3I
Off
Crowbar
1 Second
Pulse
Detected
Event
(one of 30
events;
PWBTN is
separate)
100 ms
Pulse
No_Vdd
PWBTIN
PWBTOUT
_MODE
Resume
from
Power Fail
4 s
Pulse
Status
Set
PWBTIN