MC81F4x16
17. WATCH TIMER
Watch timer functions include real-time and watch-time measurement and interval timing for the
system clock.
Watch timer has the following functional components:
- Real time and watch time measurement
7
- Using a main or sub clock source (main clock divided by 2 (fx/128) or sub clock(fxt))
- Timing tests in high-speed mode
- Watch timer interrupt generation
- Watch timer status and control register (WTSCR)
Enable/Disable
WTEN
WTIE
Watch timer INT enable
WTINT
60.0S
30.0S
fxx/128
fxt
1.0S
0.5S
Clock
Selector
Frequency
Dividing
Circuit
fw
Selector
Circuit
WTIR
32.768KHz
0.25S
10mS
Watch timer INT request
WTSC
WTSS
fxx = System clock (where fx = 4.19MHz)
fxt = Sub clock (32.768KHz)
fw = Watch timer Frequency
Figure 17-1 Watch Timer Block Diagram
114
October 19, 2009 Ver.1.35
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