Intel 386 User Manual

17-7
WATCHDOG TIMER UNIT
17.4 REGISTER DEFINITIONS
This section describes the registers associated with the WDT, and explains how these registers
can be used to enable and use each WDT mode.
Table 17-2 describes the registers associated with the WDT.
Table 17-2. WDT Registers
Register Address Description
WDTCLR 0F4C8H Watchdog Timer Clear:
Write the lockout sequence to this location. Circuitry at this address decodes
the lockout sequence to enable watchdog mode, reload the counter, or both.
This location is used only for watchdog mode.
WDTCNTH
WDTCNTL
(read only)
0F4C4H
0F4C6H
WDT Counter:
These registers hold the current value of the WDT down-counter. Software
can read them to determine the current count value. Any reload event
reloads these registers with the contents of WDTRLDH and WDTRLDL.
WDTRLDH
WDTRLDL
(read/write)
0F4C0H
0F4C2H
WDT Reload Value:
Write the reload value to these registers, using two word writes. After a
lockout sequence is issued, these registers cannot be written again until after
a device reset. A reload event (each WDT mode has its own; refer to
Sections 17.2.2 through 17.2.4) reloads WDTCNTH and WDTCNTL with the
contents of these registers.
WDTSTATUS
(read/write)
0F4CAH WDT Status:
This register contains one read-only bit (WDTEN) that indicates whether
watchdog mode is enabled and two read/write bits that control bus monitor
mode and the WDT clock. A lockout sequence sets the WDTEN bit and
clears the two read/write bits, disabling bus monitor mode and enabling the
WDT clock. After a lockout sequence is issued, a write to this register has no
effect unless the device is reset.
Software can read this register to determine the current status of the WDT
and (unless a lockout sequence has been issued) can set the BUSMON bit to
enable bus monitor mode or set the CLKDIS bit to disable the WDT.
PWRCON
(read/write)
0F800H Power Control register:
This register holds the WDTRDY bit that is used to enable/disable internal
READY# generation for the WDT Bus Monitor mode.

Intel 386 Specifications

General

Brand	Intel
Model	386
Category	Computer Hardware
Language	English