LPC47M14X datasheet(116/205 Pages) SMSC

116 / 205 page

SMSC DS – LPC47M14X

Page 116

Rev. 03/19/2001

6.16 PME SUPPORT

The LPC47M14x offers support for power management events (PMEs), also referred to as a System Control Interrupt

(SCI) events in an ACPI system. A power management event is indicated to the chipset via the assertion of the

nIO_PME signal. In the LPC47M14x, the nIO_PME is asserted by active transitions on the ring indicator inputs nRI1

and nRI2, valid NEC infrared remote control frames, active keyboard-data edges, active mouse-data edges,

programmable edges on GPIO pins and fan tachometer event. The GP42/nIO_PME pin, when selected for the

nIO_PME function, can be programmed to be active high or active low via the polarity bit in the GP42 register. The

output buffer type of the pin can be programmed to be open-drain or push-pull via bit 7 of the GP42 register. The

nIO_PME pin function defaults to active low, open-drain output.

The PME functionality is controlled by the PME status and enable registers in the runtime registers block, which is

located at the address programmed in configuration registers 0x60 and 0x61 in Logical Device A. The PME Enable

bit, PME_EN, globally controls PME Wake-up events. When PME_EN is inactive, the nIO_PME signal can not be

asserted. When PME_EN is asserted, any wake source whose individual PME Wake Enable register bit, is asserted

can cause nIO_PME to become asserted.

The PME Wake Status register indicates that an enabled wake source has occurred, and if the PME_EN bit is set,

asserted the nIO_PME signal. The PME Status bit is asserted by active transitions of PME Wake sources.

PME_Status will become asserted independent of the state of the global PME enable bit, PME_En.

The following pertains to the PME status bits for each event:

The output of the status bit for each event is combined with the corresponding enable bit to set the PME

status bit.

The status bit for any pending events must be cleared in order to clear the PME_STS bit.

For the GPIO events, the polarity of the edge used to set the status bit and generate a PME is controlled by the

polarity bit of the GPIO control register. For non-inverted polarity (default) the status bit is set on the low-to-high

edge. If the EETI function is selected for a GPIO then both a high-to-low and a low-to-high edge will set the

corresponding PME status bits. Status bits are cleared on a write of ‘1’.

The PME Wake registers also include status and enable bits for the fan tachometer input.

See the “Keyboard and Mouse PME Generation” section for information about using the keyboard and mouse signals

to generate a PME.

In the LPC47M14x the nIO_PME pin can be programmed to be an open drain, active low, driver. The LPC47M14x

nIO_PME pin is fully isolated from other external devices that might pull the nIO_PME signal low; i.e., the nIO_PME

signal is capable of being driven high externally by another active device or pullup even when the LPC47M14x VCC

is grounded, providing VTR power is active. The LPC47M14x nIO_PME driver sinks 6mA at .55V max (see section

4.2.1.1 DC Specifications, page 122, in the “PCI Local Bus Specification,” revision 2.1).

The PME registers are run-time registers as follows. These registers are located in system I/O space at an offset

from PME_BLK, the address programmed in Logical Device A at registers 0x60 and 0x61.

The following registers are for GPIO wakeup events:

PME Wake Status 2 (PME_STS2), PME Wake Enable 2 (PME_EN2)

PME Wake Status 3 (PME_STS3), PME Wake Enable 3 (PME_EN3)

PME Wake Status 4 (PME_STS4), PME Wake Enable 4 (PME_EN4)

PME Wake Status 5 (PME_STS5), PME Wake Enable 5 (PME_EN5)

See PME register description in the “Runtime Registers” Section.

LPC47M14X Datasheet(PDF) 116 Page - SMSC Corporation

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