Watch Timer Configuration - Fujitsu MB90480 Series Hardware Manual

11.2 Watch Timer Configuration

The watch timer is composed of four blocks that include the following:
• Interval selector
• Watch counter
• Watch timer interrupt generating circuit
• Watch timer control register (WTC)
■
Block diagram of watch timer
Figure 11.2-1 is a block diagram of the watch timer.
WDCS SCE
Sub-clock
❍ Watch counter
This is a 15-bit up-counter that uses the sub-clock as the clock source.
❍ Interval selector
This selector selects one of seven types for watch timer interrupt intervals.
❍ Interrupt generating circuit
This circuit generates the interval interrupts of the watch timer.
❍ Watch timer control register (WTC)
This register controls operation of the watch timer and watch timer interrupt, and it specifies the
clock source for the watchdog timer.
Figure 11.2-1 Block diagram of watch timer
Watch timer control register (WTC)
WTIE WTOF WTR
Clear
8
2
9
2
10
2
Watch counter
11
2
12
2
13
2
14
2
12 13 14 15
2 2 2 2
WTC2 WTC1 WTC0
Interval selector
CHAPTER 11 WATCH TIMER
Interrupt
Interrupt of
generating
watch timer
circuit
To watchdog timer
211