SC2200 datasheet(89/433 Pages) NSC

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General Configuration Block (Continued)

WATCHDOG Interrupt

The WATCHDOG interrupt (if configured and enabled) is

routed to an IRQ signal. The IRQ signal is programmable

via the INTSEL register (Offset 38h, described in Table 3-2

"Multiplexing, Interrupt Selection, and Base Address Regis-

ters" on page 81). The WATCHDOG interrupt is a share-

able, active low, level interrupt.

WATCHDOG SMI

The WATCHDOG SMI is recognized by the Core Logic

module as internal input signal EXT_SMI0#. To use the

WATCHDOG SMI, Core Logic registers must be configured

appropriately.

3.3.2

WATCHDOG Registers

Table 3-3 describes the WATCHDOG registers.

3.3.2.1

Usage Hints

• SMM code should set bit 8 of the WDCNFG register to 1

when entering ACPI C3 state, if the WATCHDOG timer

is to be suspended. If this is not done, the WATCHDOG

timer is functional during C3 state.

• SMM code should set bit 8 of the WDCNFG register to

1, when entering ACPI S1 and S2 states if the

WATCHDOG timer is to be suspended. If this is not

done, the WATCHDOG timer is functional during S1 and

S2 states.

Table 3-3. WATCHDOG Registers

Bit

Description

Offset 00h-01h

WATCHDOG Timeout Register - WDTO (R/W)

Reset Value: 0000h

This register specifies the programmed WATCHDOG timeout period.

15:0

Programmed timeout period.

Offset 02h-03h

WATCHDOG Configuration Register - WDCNFG (R/W)

Reset Value: 0000h

This register selects the signal to be generated when the timer reaches 0, whether or not to disable the 32 KHz input clock during low

power states, and the prescaler value of the clock input.

15:9

Reserved. Write as read.

WD32KPD (WATCHDOG 32 KHz Power Down).

32 KHz clock is enabled.

32 KHz clock is disabled, when the GX1 module asserts its internal SUSPA# signal.

This bit is cleared to 0, when POR# is asserted or when the GX1 module deasserts its internal SUSPA# signal (i.e., on

SUSPA# rising edge). See Section 3.3.2.1 "Usage Hints" on page 89.

7:6

WDTYPE2 (WATCHDOG Event Type 2).

00: No action

01: Interrupt

10: SMI

11: System reset

This field is reset to 0 when POR# is asserted. Other system resets do not affect this field.

5:4

WDTYPE1 (WATCHDOG Event Type 1).

00: No action

01: Interrupt

10: SMI

11: System reset

This field is reset to 0 when POR# is asserted. Other system resets do not affect this field.

3:0

WDPRES (WATCHDOG Timer Prescaler). Divide 32 KHz by:

0000: 1

0100: 16

1000: 256

1100: 4096

0001: 2

0101: 32

1001: 512

1101: 8192

0010: 4

0110: 64

1010: 1024

1110: Reserved

0011: 8

0111: 128

1011: 2048

1111: Reserved

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