SC2200 NSC [National Semiconductor], SC2200 Datasheet - Page 89

• Manufacturer Part Number: SC2200
• Description: Thin Client On a Chip
• Manufacturer: NSC [National Semiconductor]

Revision 3.0
General Configuration Block
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.
Offset 00h-01h
This register specifies the programmed WATCHDOG timeout period.
Offset 02h-03h
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.
15:0
15:9
Bit
7:6
5:4
3:0
8
Description
Programmed timeout period.
Reserved. Write as read.
WD32KPD (WATCHDOG 32 KHz Power Down).
0: 32 KHz clock is enabled.
1: 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.
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.
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.
WDPRES (WATCHDOG Timer Prescaler). Divide 32 KHz by:
0000: 1
0001: 2
0010: 4
0011: 8
0100: 16
0101: 32
0110: 64
0111: 128
WATCHDOG Configuration Register - WDCNFG (R/W)
WATCHDOG Timeout Register - WDTO (R/W)
Table 3-3. WATCHDOG Registers
(Continued)
1000: 256
1001: 512
1010: 1024
1011: 2048
89
3.3.2
Table 3-3 describes the WATCHDOG registers.
3.3.2.1
• SMM code should set bit 8 of the WDCNFG register to 1
• SMM code should set bit 8 of the WDCNFG register to
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.
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.
1100: 4096
1101: 8192
1110: Reserved
1111: Reserved
WATCHDOG Registers
Usage Hints
Reset Value: 0000h
Reset Value: 0000h
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