
145
CHAPTER 7 APPLICATIONS OF WATCH TIMER
Figure 7-2. Format of Watch Timer Mode Control Register
(
μ
PD78002, 78002Y, 78014, 78014Y, 78018F, 78018FY, 78014H subseries)
7
6
5
4
3
2
Symbol
1
0
TMC23
Selects set time of watch flag
2
14
/f
W
(0.5s)
2
13
/f
W
(0.25s)
2
5
/f
W
(977 s)
2
4
/f
W
(488 s)
FF4AH
TMC20
TMC2
TMC21
TMC23 TMC22
TMC24
TMC25
TMC26
0
Address
At reset
R/W
00H
R/W
TMC20
0
0
1
0
1
1
TMC21 Controls operation of prescaler
0
Clears after operation stopped
1
Enables operation
TMC22 Controls operation of 5-bit counter
0
Clears after operation stopped
1
Enables operation
TMC26
Selects interval time of prescaler
2
4
/f
W
(488 s)
2
5
/f
W
(977 s)
μ
0
0
TMC25
0
0
0
2
6
/f
W
(1.95 ms)
2
7
/f
W
(3.91 ms)
2
8
/f
W
(7.81 ms)
2
9
/f
W
(15.6 ms)
0
1
1
TMC24
0
1
0
1
1
1
0
0
Others
Setting prohibited
0
1
Caution Do not often clear the prescaler when the watch timer is used.
Remarks 1.
f
W
: watch timer clock frequency (f
X
/2
8
or f
XT
)
2.
( ): at f
W
= 32.768 kHz