PC87591L datasheet(319/437 Pages) NSC

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Host Controller Interface Modules (Continued)

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The following wake-up input events are detected by the MSWC:

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Software events

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IRQ from SuperI/O modules

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Modem Ring (RI1 and RI2)

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Telephone Ring (RING input)

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ACPI state change

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Legacy off event

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RTC Alarm

When an input event is detected, the corresponding status bit in both host and core status registers is set to 1, regardless

of any Routing Enable bit setting. If both the status bit and a Routing Enable bit corresponding to a specific event are set to

1 (no matter in what order), the output pin corresponding to that Routing Enable bit is asserted.

A status bit is cleared by writing 1 to it. Writing 0 to a status bit does not change its value. Clearing the routing enable bit of

an event prevents it from issuing the corresponding system notification (output event) but does not affect the status bit.

Figure 105 shows the routing scheme of detected wake-up events to the various means of system notification (i.e., output

events).

Both the core and the host have status registers; thus both core and host software can monitor the various event status bits.

This enables handling of events via wake-up logic that is implemented as part of the Embedded Controller firmware, and

passing the wake-up notifications through the Power Management host-interface protocol. The core uses a mask register

(WK_SMIENn) to define which of the status bits it should respond to.

It is recommended that each of the wake-up sources be handled by one handler routine on the host (i.e., SMI, SCI or IRQ

triggered) or the core.

Software Event

A software event may be used to trigger a wake-up event via software control. A software event to the host is active when

the Software Event Status bit in WK_STS0 register is set. A software event to the core is active when the Software Event

Status bit in MSHES0 register is set.

The software event may be activated (i.e., the status bits in WK_STS0 and MSHESO registers are set) by writing 1 to the

Software Event Status bit in WK_STS0 register when the bit is cleared. Once this bit is set to 1, writing 1 to the bit clears it.

WK_STS0 is accessible by the host only when VDD is present. The software event can be activated by the host only when

VDD is present. The software event may be activated by the core by the core access to the Host-Controlled Module bridge

even when VDD is off.

When HSECM bit in MSWCTL1 register is cleared, the Software Event Status bit in MSHES0 is set on a change of the re-

spective bit in WK_STS0 register from 0 to 1. When HSECM bit is set, the Software Event Status bit in MSHES0 is set on a

write of a 1 to the respective bit in WK_STS0. The Software Event Status bit in MSHES0 is cleared by writing 1 to it.

Module IRQ Wake-Up Event

A module IRQ wake-up event is defined as the leading edge of the IRQ assertion of the RTC.

To enable the IRQ of a specific logical device to trigger a wake-up event, the associated enable bit must be set to 1. This is

bit 4 of the Interrupt Number and Wake-Up on IRQ Enable register, located at index 7016 in the configuration space of the

logical device (see Table 52 on page 339). When this bit is set, any IRQ assertion of the corresponding logical device acti-

vates the module IRQ wake-up event. Therefore, the module IRQ wake-up event is a combination of all IRQ signals of the

logical devices for which wake-up on IRQ is enabled.

When the event is detected as active, its associated status bit (bit 7 of WK0_STS register) is set to 1. If the associated enable

bit (bit 7 of WK_EN0 register) is also set to 1, the PWUREQ output is asserted and remains asserted until the status bit is

cleared.

Since VDD powers IRQ generation of the logical devices, a module IRQ event can be activated only when VDD is present

(see Section 6.1 on page 335 for a list of logical devices).

Modem Ring

High to low transitions on RI1 (or RI2) indicate the detection of a ring in an external modem connected to Serial Port 1 (or

Serial Port 2) and can be used as wake-up events.

Telephone Ring

A telephone ring is detected by the MSWC by processing the raw signal coming directly from the telephone line into the

RING input pin. Detection of a pulse train, with a frequency higher than 16 Hz lasting at least 0.19 sec, is used as a wake-

up event.

PC87591L Datasheet(PDF) 319 Page - National Semiconductor (TI)

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