UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
223 of 464
NXP Semiconductors
UM10850
Chapter 15: LPC5410x Windowed Watchdog Timer (WWDT)
•
Set a value for the watchdog warning interrupt in the WARNINT register if a warning
interrupt is desired.
•
Enable the Watchdog by writing 0xAA followed by 0x55 to the FEED register.
•
The Watchdog must be fed again before the Watchdog counter reaches zero in order
to prevent a watchdog event. If a window value is programmed, the feed must also
occur after the watchdog counter passes that value.
When the Watchdog Timer is configured so that a watchdog event will cause a reset and
the counter reaches zero, the CPU will be reset, loading the stack pointer and program
counter from the vector table as for an external reset. The Watchdog time-out flag
(WDTOF) can be examined to determine if the Watchdog has caused the reset condition.
The WDTOF flag must be cleared by software.
When the Watchdog Timer is configured to generate a warning interrupt, the interrupt will
occur when the counter matches the value defined by the WARNINT register.
15.5.1 Block diagram
The block diagram of the Watchdog is shown below in the
. The synchronization
logic (PCLK - WDCLK) is not shown in the block diagram.
Fig 34. Windowed Watchdog timer block diagram
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