CHAPTER 11 WATCHDOG TIMER FUNCTIONS
User’s Manual U16896EJ2V0UD
355
Table 11-5. Watchdog Timer 2 Clock Selection
WDCS24 WDCS23 WDCS22 WDCS21
WDCS20
Selected
Clock
Program Loop Detection Time
0 0 0 0 0
2
12
/f
R
17.1
ms
(f
R
= 240 kHz (TYP.))
Note
0 0 0 0 1
2
13
/f
R
34.1
ms
(f
R
= 240 kHz (TYP.))
Note
0 0 0 1 0
2
14
/f
R
68.2
ms
(f
R
= 240 kHz (TYP.))
Note
0 0 0 1 1
2
15
/f
R
136.5
ms
(f
R
= 240 kHz (TYP.))
Note
0 0 1 0 0
2
16
/f
R
273.1
ms
(f
R
= 240 kHz (TYP.))
Note
0 0 1 0 1
2
17
/f
R
546.1
ms
(f
R
= 240 kHz (TYP.))
Note
0 0 1 1 0
2
18
/f
R
1092.3 ms (f
R
= 240 kHz (TYP.))
Note
0 0 1 1 1
2
19
/f
R
2184.5 ms (f
R
= 240 kHz (TYP.))
Note
0 1 0 0 0
2
9
/f
XT
15.625 ms (f
XT
= 32.768 kHz)
0 1 0 0 1
2
10
/f
XT
31.25
ms
(f
XT
= 32.768 kHz)
0 1 0 1 0
2
11
/f
XT
62.5
ms
(f
XT
= 32.768 kHz)
0 1 0 1 1
2
12
/f
XT
125
ms
(f
XT
= 32.768 kHz)
0 1 1 0 0
2
13
/f
XT
250
ms
(f
XT
= 32.768 kHz)
0 1 1 0 1
2
14
/f
XT
500
ms
(f
XT
= 32.768 kHz)
0 1 1 1 0
2
15
/f
XT
1000
ms
(f
XT
= 32.768 kHz)
0 1 1 1 1
2
16
/f
XT
2000
ms
(f
XT
= 32.768 kHz)
1
×
×
×
×
Operation stopped
Note
For frequency characteristics (error) of internal oscillation clock (f
R
), refer to
CHAPTER 28 ELECTRICAL
SPECIFICATIONS
.
(2) Watchdog timer enable register (WDTE)
The counter of watchdog timer 2 is cleared and counting restarted by writing “ACH” to the WDTE register.
The WDTE register can be read or written in 8-bit units.
Reset sets this register to 9AH.
WDTE
After reset: 9AH R/W Address: FFFFF6D1H
Cautions 1. When a value other than “ACH” is written to the WDTE register, an overflow signal is
forcibly output.
2. When a 1-bit memory manipulation instruction is executed for the WDTE register, an
overflow signal is forcibly output.
3. The read value of the WDTE register is always “9AH” (value that differs from written value
“ACH”).
4. To intentionally generate an overflow signal, write a value other than “ACH” to the WDTE
register only once, or write data to the WDTM2 register only twice.
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