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CHAPTER 9 Watch timer
9.2
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)
I Block Diagram of Watch Timer
Watch timer counter
1
SCLK
2
Power-on reset
Hardware standby transmission
Stop mode transmission
Watch timer interrupt
OF
: Over flow
SCLK
: Subclock
The actual interrupt request number of the watch timer is as follows:
Interrupt request number: #28 (1C
G
Watch timer counter
The watch timer counter is a 15-bit up counter that uses the sub clock (SCLK) as a count clock.
G
Counter clear circuit
The counter-clear circuit clears the watch timer counter.
280
Figure 9.2-1 Block Diagram of Watch Timer
5
6
2
3
4
2
2
2
2
2
Counter
clear
circuit
WDCS SCE WTIE
Watch timer co ntro l registe r (WTC)
)
H
7
8
9
10
11
2
2
2
2
2
2
OF
OF
OF
OF
OF
Interval timer
selector
WTOF WTR
WTC2
To watchdog timer
12
13
14
15
2
2
2
OF
OF
OF
To subclock
oscillation stabilization
waiting time
WTC1 WTC0
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