HD6433640 HITACHI [Hitachi Semiconductor], HD6433640 Datasheet - Page 281

• Manufacturer Part Number: HD6433640
• Description: H8/3644 Series Hardware Manual
• Manufacturer: HITACHI [Hitachi Semiconductor]

9.6
9.6.1
The watchdog timer has an 8-bit counter that is incremented by an input clock. If a system
runaway allows the counter value to overflow before being rewritten, the watchdog timer can reset
the chip internally.
Features
Features of the watchdog timer are given below.
Block Diagram
Figure 9.35 shows a block diagram of the watchdog timer.
Legend:
TCSRW:
TCW:
PSS:
Incremented by internal clock source (ø/8192).
A reset signal is generated when the counter overflows. The overflow period can be set from 1
to 256 times 8192/ø (from approximately 2 ms to 500 ms when ø = 4.19 MHz).
ø
Watchdog Timer
Overview
Timer control/status register W
Timer counter W
Prescaler S
PSS
Figure 9.35 Block Diagram of Watchdog Timer
ø/8192
TCSRW
TCW
Internal reset
signal
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