K60P100M100SF2RM Datasheet, PDF (524/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Backup Reset Generator
Note
Do not enable the watchdog interrupt during these tests. If
required, you must ensure that the effective time-out value is
greater than WCT time. See Generated Resets and Interrupts for
more details.
23.5 Backup Reset Generator
The backup reset generator generates the final reset which goes out to the system. It has a
backup mechanism which takes care that in case the bus clock stops and prevents the
main state machine from generating a reset exception/interrupt, the watchdog timer's
time-out is separately routed out as a reset to the system. Two successive timer time-outs
without an intervening system reset result in the backup reset generator routing out the
time-out signal as a reset to the system.
23.6 Generated Resets and Interrupts
The watchdog generates a reset on the following events (referred to as exceptions at some
places in this document):
• A watchdog time-out.
• Failure to unlock the watchdog within WCT time after system reset deassertion.
• No update of the control and configuration registers within the WCT window after
unlocking. At least one of the following registers must be written to within the WCT
window to avoid reset:
• WDOG_ST_CTRL_H, WDOG_ST_CTRL_L
• WDOG_TO_VAL_H, WDOG_TO_VAL_L
• WDOG_WIN_H, WDOG_WIN_L
• WDOG_PRESCALER
• A value other than the unlock sequence or the refresh sequence is written to the
unlock and/or refresh registers, respectively.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
524
Freescale Semiconductor, Inc.