
CHAPTER 8 WATCH TIMER
152
Figure 8-2. Timer Clock Select Register 2 Format
TCL20
TCL2
7
6
5
4
3
2
Symbol
1
0
TCL22
Count Clock Selection
FF42H
TCL21
0
TCL22
TCL24
TCL25
TCL26
TCL27
Address
After Reset
R/W
00H
R/W
Watchdog Timer Mode
0
f
X
/2
3
(625 kHz)
f
X
/2
4
(313 kHz)
f
X
/2
5
(156 kHz)
f
X
/2
6
(78.1 kHz)
f
X
/2
7
(39.1 kHz)
f
X
/2
8
(19.5 kHz)
f
X
/2
9
(9.8 kHz)
f
X
/2
11
(2.4 kHz)
0
0
0
1
1
1
1
TCL24 Watch Timer Count Clock Selection
Note
f
X
/2
8
(19.5 kHz)
0
1
f
XT
(32.768 kHz)
TCL27
Buzzer Output Frequency Selection
0
Buzzer output disable
f
X
/2
10
(4.9 kHz)
f
X
/2
11
(2.4 kHz)
f
X
/2
12
(1.2 kHz)
1
1
1
1
Setting prohibited
Interval Timer Mode
f
X
/2
4
(313 kHz)
f
X
/2
5
(156 kHz)
f
X
/2
6
(78.1 kHz)
f
X
/2
7
(39.1 kHz)
f
X
/2
8
(19.5 kHz)
f
X
/2
9
(9.8 kHz)
f
X
/2
10
(4.9 kHz)
f
X
/2
12
(1.2 kHz)
TCL21
0
0
1
1
0
0
1
1
TCL20
0
1
0
1
0
1
0
1
TCL26
×
0
0
1
1
TCL25
×
0
1
0
1
Note
When using a main system clock of 1.25 MHz or less and FIP controller/driver, select f
X
/2
8
as the counter
clock for watch timer.
Caution
If TCL2 is to be rewritten in data other than identical data, the timer operation must be
stopped first.
Remarks 1.
f
X
: Main system clock frequency
2.
f
XT
: Subsystem clock oscillation frequency
3.
×
: Don’t care
4.
Figures in parentheses apply to operation with f
X
= 5.0 MHz or f
XT
= 32.768 kHz.