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Functions, Function of the hardware watchdog timer, Period of the hardware watchdog timer – FUJITSU MB91460 SERIES FR60 User Manual

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Chapter 21 Hardware Watchdog Timer

4.Functions

4. Functions

If the watchdog timer is not cleared periodically, a setting initialization reset (INIT) occurs. In this case the
value of registers in CPU is not guaranteed.

Function of the hardware watchdog timer

After releasing INITX the hardware watchdog timer starts immediately without stabilization time. If the timer is
not cleared periodically, setting initialization (INIT) reset occurs.

Period of the hardware watchdog timer

The timer width is 16-bit. Since the RC oscillator is used as clock source of the hardware watchdog timer, the
duration of the timer deviates with the RC oscillator accuracy:

Note: The watchdog duration elongation (ED1-0) setting is not available on MB91V460. In that case ED1-0 is
always “00”.

ED1-0

Min.

Typ.

Max.

RC oscillation cycle (u s)

5

10

20

Watchdog term (ms)

00

327.68

655.36

1310.72

01

655.36

1310.72

2621.44

10

1310.72

2621.44

5242.88

11

2621.44

5242.88

10485.76