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UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
921 of 1269
NXP Semiconductors
UM10503
Chapter 34: LPC43xx Windowed Watchdog timer (WWDT)
Once the
WDEN
,
WDPROTECT
, or
WDRESET
bits are set they can not be cleared by
software. Both flags are cleared by an external reset or a Watchdog timer reset.
WDTOF
The Watchdog time-out flag is set when the Watchdog times out, when a feed
error occurs, or when WDPROTECT =1 and an attempt is made to write to the TC
register. This flag is cleared by software writing a 0 to this bit.
WDINT
The Watchdog interrupt flag is set when the Watchdog counter reaches the value
specified by WDWARNINT. This flag is cleared when any reset occurs, and is cleared by
software by writing a 1 to this bit.
Watchdog reset or interrupt will occur any time the watchdog is running and has an
operating clock source. Any clock source works in Sleep mode, and the IRC works in
Deep-sleep mode. If a watchdog interrupt occurs in Sleep or Deep-sleep mode, it will
wake up the device.
Table 773. Watchdog Mode register (MOD - 0x4008 0000) bit description
Bit
Symbol
Value
Description
Reset value
0
WDEN
Watchdog enable bit. This bit is Set Only.
0
0
The watchdog timer is stopped.
1
The watchdog timer is running.
1
WDRESET
Watchdog reset enable bit. This bit is Set Only.
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.
This flag is cleared by software writing a 0 to this
bit.
0 (Only after
external reset)
3
WDINT
Watchdog interrupt flag. Set when the timer
reaches the value in the WARNINT register.
Cleared by software by writing a 1 to this bit.
0
4
WDPROTECT
Watchdog update mode. This bit is Set Only.
0
0
The watchdog time-out value (WDTC) can be
changed at any time.
1
The watchdog time-out value (WDTC) can be
changed only after the counter is below the value
of WDWARNINT and WDWINDOW.
7:5
-
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit
is not defined.
NA