
71
CHAPTER 4 APPLICATIONS OF WATCHDOG TIMER
Figure 4-2. Format of Timer Clock Select Register 2 (
μ
PD780001)
Caution To change the data of TCL2 except when writing the same data, once stop the timer operation.
Remarks 1.
f
X
: main system clock oscillation frequency
: don’t care
: f
X
= 10.0 MHz
2.
×
3.
( )
TCL27 TCL26 TCL25
0
0
TCL22 TCL21 TCL20
TCL2
7
6
5
4
3
2
1
0
Symbol
Address
At reset
R/W
FF42H
00H
R/W
TCL22 TCL21 TCL20
0
0
0
0
0
1
0
0
1
1
0
1
1
1
0
0
0
1
1
1
1
1
0
1
Selects count clock of watchdog timer
f
X
/2
4
(625 kHz)
f
X
/2
5
(313 kHz)
f
X
/2
6
(156 kHz)
f
X
/2
7
(78.1 kHz)
f
X
/2
8
(39.1 kHz)
f
X
/2
9
(19.5 kHz)
f
X
/2
10
(9.8 kHz)
f
X
/2
12
(2.4 kHz)
TCL27
0
TCL26
×
TCL25
×
1
1
0
0
0
1
1
1
1
1
0
1
Selects frequency of buzzer output
Disables buzzer output
f
X
/2
10
(9.8 kHz)
f
X
/2
11
(4.9 kHz)
f
X
/2
12
(2.4 kHz)
Setting prohibited