User’s Manual U16899EJ2V0UD
231
CHAPTER 10 WATCHDOG TIMER
10.1 Functions of Watchdog Timer
The watchdog timer is used to detect an inadvertent program loop. If a program loop is detected, an internal reset
signal is generated.
When a reset occurs due to the watchdog timer, bit 4 (WDTRF) of the reset control flag register (RESF) is set to 1.
For details of RESF, refer to CHAPTER 20 RESET FUNCTION.
Table 10-1. Loop Detection Time of Watchdog Timer
Loop Detection Time
During Ring-OSC Clock Operation
During High-Speed System Clock Operation
2
11
/f
R
(4.27 ms)
2
13
/f
XP
(819.2
µ
s)
2
12
/f
R
(8.53 ms)
2
14
/f
XP
(1.64 ms)
2
13
/f
R
(17.07 ms)
2
15
/f
XP
(3.28 ms)
2
14
/f
R
(34.13 ms)
2
16
/f
XP
(6.55 ms)
2
15
/f
R
(68.27 ms)
2
17
/f
XP
(13.11 ms)
2
16
/f
R
(136.53 ms)
2
18
/f
XP
(26.21 ms)
2
17
/f
R
(273.07 ms)
2
19
/f
XP
(52.43 ms)
2
18
/f
R
(546.13 ms)
2
20
/f
XP
(104.86 ms)
Remarks 1. f
R
: Ring-OSC clock oscillation frequency
2. f
XP
: High-speed system clock oscillation frequency
3. Figures in parentheses apply to operation at f
R
= 480 kHz (MAX.), f
XP
= 10 MHz
The operation mode of the watchdog timer (WDT) is switched according to the option byte setting of the on-chip
Ring-OSC as shown in Table 10-2.
Содержание MuPD78F0132H
Страница 2: ...User s Manual U16899EJ2V0UD 2 MEMO ...