UPD784218 Datasheet, PDF (45/92 Pages) NEC – 16-/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784218, 784218Y
Figure 8-16. Watch Timer Block Diagram
fXX/2⁷
fXT
fW
Prescaler
fW fW fW fW fW fW
2⁴
2⁵
2⁶ 2⁷
2⁸ 2⁹
fW
2¹⁴
5-bit counter
fW
2⁵
INTWT
INTTM3
To 16-bit timer/
event counter
8.12 Watchdog Timer
A watchdog timer is provided to detect a CPU runaway. This watchdog timer generates a non-maskable or
maskable interrupt unless it is cleared by software within a specified interval time. Once enabled to operate, the
watchdog timer cannot be stopped by software. Whether the interrupt by the watchdog timer or the interrupt input
from the NMI pin takes precedence can be specified.
Figure 8-17. Watchdog Timer Block Diagram
fCLK
Timer
fCLK/2²¹
fCLK/2²⁰
fCLK/2¹⁹
fCLK/2¹⁷
INTWDT
Clear signal
Remark fCLK: Internal system clock (fXX to fXX/8)
Data Sheet U12304EJ2V0DS00
45