Hi Phil
Look for the definition of ACTIVATE_WATCHDOG() (in app_hw_kinetis.h).
An example is:
UNLOCK_WDOG(); WDOG_TOVALL = (2000/5); WDOG_TOVALH = 0; WDOG_STCTRLH = (WDOG_STCTRLH_STNDBYEN | WDOG_STCTRLH_WAITEN | WDOG_STCTRLH_STOPEN | WDOG_STCTRLH_WDOGEN | WDOG_STCTRLH_ALLOWUPDATE) // watchdog enabled to generate reset on 2s timeout (further updates allowed)
Here the timeout is set to 2s (the 2000/5 - or 2000ms/5, where the /5 is due to the watchdog timer's clock to convert to seconds).
The sequence with the unlock at the beginning can be repeated (with different settings) as long as WDOG_STCTRLH_ALLOWUPDATE is set. Once WDOG_STCTRLH_ALLOWUPDATE is removed it will be locked so no further changes (nor stopping) are allowed.
The watchdog can also be disabled by removing WDOG_STCTRLH_WDOGEN.
Regards
Mark
P.S. This is for most K parts - KL parts tend to have a different watchdog as do KE parts but the method used should be evident from their corresponding macros.