Watch Timer - Fujitsu FR60 Hardware Manual

3.12

Watch Timer

The watch timer is a 15-bit free-run timer that performs incremental counting in
synchronization with the subclock.
The watch timer has an interval timer function to generate interrupts repeatedly at fixed
time intervals.
■ Interval Time
Table 3.12-1 lists the types of interval times. Select a time interval from one of the following four types.
Table 3.12-1 Types of Interval Time
(about 30.5 µs)
1/F
CL
Note: F
CL
■ Block Diagram of the Watch Timer
Figure 3.12-1 shows the block diagram of the watch timer.
Watch timer
counter
Watch interrupt
Watch timer control
register (WPCR)
F : Subclock source oscillation
CL
The numbers in the parentheses indicate the intervals
when the subclock source oscillation is 32.768 kHz.
Subclock cycle
indicates the subclock oscillation frequency.
Figure 3.12-1 Block Diagram of the Watch Timer
0 1 2
F 1 2 3
CL
2 2 2
WIF WIE
Interval time
10
2 F (31.25 ms)
CL
13
2 F (0.25 s)
CL
14
2 F (0.50 s)
CL
15
2 F (1.00 s)
CL
3 4 5 6 7 8 9
4 5 6 7 8 9 1 0
2 2 2 2 2 2 2
(31.25 ms)
(0.25 s)
Interval
timer
(0.5 s)
selector
Reset (INIT)
10 11 12 13 14
11 1 2 1 3 1 4 1 5
2 2 2 2 2
(1.0 s)
Counter clear
circuit
WS1 WS0 WCL
143