245CHAPTER 11 WATCHDOG TIMER11.1 Watchdog Timer FunctionsThe watchdog timer has the following functions.• Watchdog timer• Interval timerCaution Select the watchdog timer mode or the interval timer mode with the watchdog timer mode register(WDTM) (The watchdog timer and interval timer cannot be used at the same time).(1) Watchdog timer modeAn inadvertent program loop (runaway) is detected. Upon detection of the runaway, a non-maskable interruptrequest or RESET can be generated.Table 11-1. Watchdog Timer Runaway Detection TimesRunaway Detection Time MCS = 1 MCS = 02 11 × 1/f XX 2 11 × 1/f X (410μs) 2 12 × 1/f X (819μs)2 12 × 1/f XX 2 12 × 1/f X (819μs) 2 13 × 1/f X (1.64 ms)2 13 × 1/f XX 2 13 × 1/f X (1.64 ms) 2 14 × 1/f X (3.28 ms)2 14 × 1/f XX 2 14 × 1/f X (3.28 ms) 2 15 × 1/f X (6.55 ms)2 15 × 1/f XX 2 15 × 1/f X (6.55 ms) 2 16 × 1/f X (13.1 ms)2 16 × 1/f XX 2 16 × 1/f X (13.1 ms) 2 17 × 1/f X (26.2 ms)2 17 × 1/f XX 2 17 × 1/f X (26.2 ms) 2 18 × 1/f X (52.4 ms)2 19 × 1/f XX 2 19 × 1/f X (104.9 ms) 2 20 × 1/f X (209.7 ms)Remarks 1. f XX : Main system clock frequency (f X or f X /2)2. f X : Main system clock oscillation frequency3. MCS : Bit 0 of oscillation mode selection register (OSMS)4. Figures in parentheses apply to operation with f X = 5.0 MHz.
