Section number Title Page
24.3 Functional overview......................................................................................................................................................521
24.3.1 Unlocking and updating the watchdog.........................................................................................................522
24.3.2 Watchdog configuration time (WCT)..........................................................................................................523
24.3.3 Refreshing the watchdog..............................................................................................................................524
24.3.4 Windowed mode of operation......................................................................................................................524
24.3.5 Watchdog disabled mode of operation.........................................................................................................524
24.3.6 Debug modes of operation...........................................................................................................................525
24.4 Testing the watchdog....................................................................................................................................................525
24.4.1 Quick test.....................................................................................................................................................526
24.4.2 Byte test........................................................................................................................................................526
24.5 Backup reset generator..................................................................................................................................................527
24.6 Generated resets and interrupts.....................................................................................................................................528
24.7 Memory map and register definition.............................................................................................................................528
24.7.1 Watchdog Status and Control Register High (WDOG_STCTRLH)...........................................................529
24.7.2 Watchdog Status and Control Register Low (WDOG_STCTRLL)............................................................531
24.7.3 Watchdog Time-out Value Register High (WDOG_TOVALH).................................................................531
24.7.4 Watchdog Time-out Value Register Low (WDOG_TOVALL)..................................................................532
24.7.5 Watchdog Window Register High (WDOG_WINH)..................................................................................532
24.7.6 Watchdog Window Register Low (WDOG_WINL)...................................................................................533
24.7.7 Watchdog Refresh register (WDOG_REFRESH).......................................................................................533
24.7.8 Watchdog Unlock register (WDOG_UNLOCK).........................................................................................533
24.7.9 Watchdog Timer Output Register High (WDOG_TMROUTH).................................................................534
24.7.10 Watchdog Timer Output Register Low (WDOG_TMROUTL)..................................................................534
24.7.11 Watchdog Reset Count register (WDOG_RSTCNT)..................................................................................535
24.7.12 Watchdog Prescaler register (WDOG_PRESC)..........................................................................................535
24.8 Watchdog operation with 8-bit access..........................................................................................................................535
24.8.1 General guideline.........................................................................................................................................535
24.8.2 Refresh and unlock operations with 8-bit access.........................................................................................536
24.9 Restrictions on watchdog operation..............................................................................................................................537
K21 Sub-Family Reference Manual, Rev. 3, May 2014
20 Freescale Semiconductor, Inc.