UPD78F9418A NEC, UPD78F9418A Datasheet - Page 134

• Manufacturer Part Number: UPD78F9418A
• Description: (UPD7894xxA) 8-Bit Single Chip Microcontrollers
• Manufacturer: NEC

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9.1 Functions of Watchdog Timer
134
The watchdog timer has the following functions.
• Watchdog timer
• Interval timer
Caution Select the watchdog timer mode or interval timer mode by using the watchdog timer mode
(1)
(2)
Watchdog timer
The watchdog timer is used to detect an inadvertent program loop. When the program loop is detected, a
non-maskable interrupt or the RESET signal can be generated.
Interval timer
The interval timer generates an interrupt at any intervals set in advance.
register (WDTM).
Table 9-1. Program Loop Detection Time of Watchdog Timer
f
f
X
X
: Main system clock oscillation frequency
: Main system clock oscillation frequency
2
2
2
2
2
2
2
2
Program Loop Detection Time
11
13
15
17
11
13
15
17
× 1/f
× 1/f
× 1/f
× 1/f
× 1/f
× 1/f
× 1/f
× 1/f
X
X
X
X
X
X
X
X
Interval Time
CHAPTER 9 WATCHDOG TIMER
Table 9-2. Interval Time
User’s Manual U13952EJ3V0UD
410 µ s
1.64 ms
6.55 ms
26.2 ms
410 µ s
1.64 ms
6.55 ms
26.2 ms
Operation at f
Operation at f
X
X
= 5.0 MHz
= 5.0 MHz