PC87365 datasheet(82/215 Pages) NSC

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3.0 System Wake-Up Control (SWC) (Continued)

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Six Wake-Up Extension Enable registers (WK_X1EN0,1, WK_X2EN0,1 and WK_X3EN0,1) hold three configuration bits for

each of the 16 events to allow selective routing of detected events to the Power Button (PWBTOUT) pulse generator and to

control the wake-up mode for each one of them. Figure 10 illustrates the Wake-Up Mode Control (Extension) mechanism.

Figure 10. Wake-Up Mode Control (Extension) Mechanism

To operate the power button pulse generator, the PSLDC0,1 straps must be set to enable the Power Supply Control function

(see Section 2.7). In addition, one of the following conditions must be satisfied:

SLPS5 is active (the system is in Sleep State 5), or

Legacy Power Button is enabled, or

Power Button operation in Sleep State 3 is enabled.

The two latter conditions are determined by device configuration registers. (Refer to the

Device Architecture and Configura-

tion chapter.)

In addition to monitoring various system events, the SWC operates several general-purpose I/O (GPIO) pins powered by

VSB. Four runtime data registers (SB_GPDOn and SB_GPDIn) hold a Data Out bit and a Data In bit for each VSB-powered

GPIO pin. In addition, each GPIO pin has a dedicated configuration register that controls its characteristics. These configu-

ration registers are accessed via a set of Standby GPIO Pin Select and Pin Configuration registers (SBGPSEL and SBG-

PCFG). For a detailed description of the VSB powered GPIO pins, see Section 3.4.30.

The SWC logic is powered by VSB. The SWC control and configuration registers are battery backed, powered by VPP. The

setup of the wake-up events, including programmable sequences, is retained throughout power failures (no VSB) as long as

the battery is connected. VPP is taken from VSB if VSB is greater than the minimum (Min) value defined in the Device Char-

acteristics chapter; otherwise, VBAT is used as the VPP source.

Hardware reset does not affect these registers. They are reset only by software reset or power-up of VPP.

3.3

EVENT DETECTION

3.3.1

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, respectively, and can be used as wake-up events.

3.3.2

Telephone Ring

A telephone ring is detected by the SWC 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.

The RING pulse-train detection is achieved by monitoring the falling edges on RING in time slots of 62.5 msec (a 16 Hz

cycle). A positive detection occurs if falling edges of RING are detected in three consecutive time slots, following a time slot

in which no RING falling edge is detected. This detection method guarantees the detection of a RING pulse-train with fre-

quencies higher than 16 Hz. It ﬁlters out (does not detect) pulses of less than 10 Hz and may detect pulses between 10 Hz

to 16 Hz.

WK_X2ENn.i

WK_X1ENn.i

Wake-Up Raw Event i

VDD Present

Post VDD Power-On Silence

To Event i

Detection

Logic

WK_X3ENn.i

To Power

Button

Pulse

Generator

Post VSB Power-On Silence

Enable Power Button Pulse

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