131
CHAPTER 6 WATCHDOG TIMER
6.4
Operations of Watchdog Timer Functions
The watchdog timer generates a watchdog reset when the watchdog timer counter
overflows.
■
Operations of Watchdog Timer
●
Activating watchdog timer
The watchdog timer is activated when the first time "0101
B
" is written to the watchdog control bits
(WDTC: WTE3 to WTE0) of the watchdog control register.
The watchdog timer cannot be stopped without accepting a reset upon activation.
●
Clearing watchdog timer
The watchdog timer counter is cleared the second or subsequent time "0101
B
" is written to the watchdog
control bits (WDTC: WTE3 to WTE0) of the watchdog control register.
When the counter is not cleared within the time interval of the watchdog timer, the counter overflows and
the timer generates the internal reset signal having a period of four instruction cycles.
●
Time intervals of watchdog timer
The time interval varies depending on the timing at which the watchdog timer is cleared. Figure 6.4-1
shows the relationship between the clear timings and time intervals of the watchdog timer when output
from the time-base timer is used as the count clock (oscillation frequency: 12.5 MHz).
Figure 6.4-1 Clearing Watchdog Timer and Time Interval
671.0 m
s
33
5.5 m
s
Minim
u
m time interv
a
l
Co
u
nt clock o
u
tp
u
t from
time-
bas
e timer
W
a
tchdog cle
a
r
Overflow
W
a
tchdog 1-
b
it co
u
nter
W
a
tchdog re
s
et
M
a
xim
u
m time interv
a
l
Co
u
nt clock o
u
tp
u
t from
time-
bas
e timer
W
a
tchdog cle
a
r
Overflow
W
a
tchdog 1-
b
it co
u
nter
W
a
tchdog re
s
et
Содержание F2MC-8L F202RA
Страница 2: ......
Страница 4: ......
Страница 32: ...16 CHAPTER 1 OVERVIEW ...
Страница 90: ...74 CHAPTER 3 CPU ...
Страница 142: ...126 CHAPTER 5 TIME BASE TIMER POPW A RETI ENDS END ...
Страница 150: ...134 CHAPTER 6 WATCHDOG TIMER ...
Страница 174: ...158 CHAPTER 7 8 BIT PWM TIMER User processing POPW A XCHW A T Restoring A and T POPW A RETI ENDS ...
Страница 176: ...160 CHAPTER 7 8 BIT PWM TIMER ...
Страница 220: ...204 CHAPTER 8 8 16 BIT CAPTURE TIMER COUNTER ...
Страница 240: ...224 CHAPTER 9 12 BIT PPG TIMER ...
Страница 258: ...242 CHAPTER 10 EXTERNAL INTERRUPT CIRCUIT 1 EDGE PUSHW A User processing POPW A XCHW A T POPW A RETI ENDS END ...
Страница 274: ...258 CHAPTER 11 EXTERNAL INTERRUPT CIRCUIT 2 LEVEL ...
Страница 362: ...346 CHAPTER 15 BUZZER OUTPUT ...
Страница 371: ...355 CHAPTER 16 WILD REGISTER FUNCTION 16 3 5 Data Test Set Register WROR A test register Do not access this register ...
Страница 390: ...374 CHAPTER 17 FLASH MEMORY ...
Страница 419: ...403 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Страница 434: ...418 INDEX ...
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