1. Select either quick test or byte test..2. Set a certain test mode bit to put the watchdog in the functional test mode. Settingthis bit automatically switches the watchdog timer to a fast clock source. Theswitching of the clock source is done to achieve a faster time-out and hence a fastertest.In a successful test, the timer times out after reaching the programmed time-out value andgenerates a system reset.NoteAfter emerging from a reset due to a watchdog test, unlock andconfigure the watchdog. The refresh and unlock operations andinterrupt are not automatically disabled in the test mode.24.4.1 Quick testIn this test, the time-out value of watchdog timer is programmed to a very low value toachieve quick time-out. The only difference between the quick test and the normal modeof the watchdog is that TESTWDOG is set for the quick test. This allows for a faster testof the watchdog reset mechanism.24.4.2 Byte testThe byte test is a more thorough a test of the watchdog timer. In this test, the timer is splitup into its constituent byte-wide stages that are run independently and tested for time-outagainst the corresponding byte of the time-out value register. The following figureexplains the splitting concept:Testing the watchdogK22F Sub-Family Reference Manual, Rev. 4, 08/2016526 NXP Semiconductors
