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UM10601
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
150 of 313
NXP Semiconductors
UM10601
Chapter 12: LPC800 Windowed Watchdog Timer (WWDT)
12.6 Register description
The Watchdog Timer contains the registers shown in
The reset value reflects the data stored in used bits only. It does not include the content of
reserved bits.
12.6.1 Watchdog mode register
The WDMOD register controls the operation of the Watchdog. Note that a watchdog feed
must be performed before any changes to the WDMOD register take effect.
Table 141. Register overview: Watchdog timer (base address 0x4000 4000)
Name
Access Address
offset
Description
Reset
value
Reference
MOD
R/W
0x000
Watchdog mode register. This
register contains the basic mode and
status of the Watchdog Timer.
0
TC
R/W
0x004
Watchdog timer constant register.
This 24-bit register determines the
time-out value.
0xFF
FEED
WO
0x008
Watchdog feed sequence register.
Writing 0xAA followed by 0x55 to this
register reloads the Watchdog timer
with the value contained in WDTC.
NA
TV
RO
0x00C
Watchdog timer value register. This
24-bit register reads out the current
value of the Watchdog timer.
0xFF
-
-
0x010
Reserved
-
-
WARNINT R/W
0x014
Watchdog Warning Interrupt compare
value.
0
WINDOW
R/W
0x018
Watchdog Window compare value.
0xFF FFFF
Table 142. Watchdog mode register (MOD - 0x4000 4000) bit description
Bit
Symbol
Value Description
Reset
value
0
WDEN
Watchdog enable bit. Once this bit has been written with
a 1, it cannot be re-written with a 0. Once this bit is set
to one, the watchdog timer starts running after a
watchdog feed.
0
0
The watchdog timer is stopped.
1
The watchdog timer is running.
1
WDRESET
Watchdog reset enable bit. Once this bit has been
written with a 1 it cannot be re-written with a 0.
0
0
A watchdog time-out will not cause a chip reset.
1
A watchdog time-out will cause a chip reset.
2
WDTOF
Watchdog time-out flag. Set when the watchdog timer
times out, by a feed error, or by events associated with
WDPROTECT. Cleared by software. Causes a chip
reset if WDRESET = 1.
0 (only
after
external
reset)