CHAPTER 8 WATCH TIMER
172
User’s Manual U11302EJ4V0UM
Note
Do not frequently clear the prescaler when using the watch timer.
Remarks 1.
f
W
: Watch timer clock frequency (f
X
/2
8
or f
XT
)
2.
Figures in parentheses apply to operation with f
W
= 32.768 kHz.
(2) Watch timer mode control register (TMC2)
This register sets the watch timer operating mode, watch flag set time and prescaler interval time and
enables/disables prescaler and 5-bit counter operations.
TMC2 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets TMC2 to 00H.
Figure 8-3. Format of Watch Timer Mode Control Register
7
6
5
4
3
2
1
0
0
TMC26 TMC25 TMC24 TMC23 TMC22 TMC21 TMC20
Symbol
TMC2
Address
FF4AH
After reset
00H
R/W
R/W
TMC21
0
1
Prescaler operation control
Note
Clear after operation stops
Operation enable
TMC22
0
1
5-bit counter operation control
Clear after operation stops
Operation enable
TMC23
0
1
0
1
TMC20
0
1
Watch flag set time selection
TMC26
0
0
0
0
1
1
Prescaler interval time selection
2
4
/f
W
(488 s)
Setting prohibited
TMC25
0
0
1
1
0
0
Other than above
2
14
/f
W
(0.5 s)
µ
TMC24
0
1
0
1
0
1
2
5
/f
W
(977 s)
2
13
/f
W
(0.25 s)
2
4
/f
W
(488 s)
µ
2
9
/f
W
(15.6 ms)
2
8
/f
W
(7.81 ms)
2
7
/f
W
(3.91 ms)
2
6
/f
W
(1.95 ms)
2
5
/f
W
(977 s)
µ
µ
Содержание mPD780208 Subseries
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