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CHAPTER 15 WATCH TIMER
15.2 Block Diagram of Watch Timer
The watch timer consists of the following blocks:
• Watch timer counter
• Counter clear circuit
• Interval timer selector
• Watch timer control register (WTC)
■ Block Diagram of Watch Timer
Figure 15.2-1 Block Diagram of Watch Timer
The actual interrupt request number of the watch timer is as follows:
Interrupt request number: #27(1B
H
)
●
Watch timer counter
The watch timer counter is a 15-bit up counter that uses the subclock (SCLK) as a count clock.
●
Counter clear circuit
The counter-clear circuit clears the watch timer counter.
WTOF
WTR
WTC1 WTC0WTC2
WDCS
SCE
WTIE
×
2
5
×
2
4
×
2
3
×
2
1
×
2
9
×
2
10
×
2
11
×
2
12
×
2
13
×
2
14
×
2
15
×
2
8
×
2
7
×
2
6
×
2
2
SCLK
OF
OF
OFOF
OF
OF
OF
OF
To watchdog
timer
Watch timer counter
Power-on reset
Transits to hardware standby
Transits to stop mode
Counter
clear circuit
Interval timer
selector
To subclock oscillation
stabilization wait time
Watch timer interrupt
OF : Overflow
SCLK : Subclock
Watch timer control register (WTC)