w79e532 Winbond Electronics Corp America, w79e532 Datasheet - Page 48

• Manufacturer Part Number: w79e532
• Description: 8-bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

Watchdog Control
WDIF: WDCON.3 - Watchdog Timer Interrupt flag. This bit is set whenever the time-out occurs in the
WTRF: WDCON.2 - Watchdog Timer Reset flag. This bit is set whenever a watchdog reset occurs.
EWT: WDCON.1 - Enable Watchdog timer Reset. This bit when set to 1 will enable the Watchdog
RWT: WDCON.0 - Reset Watchdog Timer. This bit is used to clear the Watchdog timer and to
Clock Control
WD1, WD0: CKCON.7, CKCON.6 - Watchdog Timer Mode select bits. These two bits select the time-
The default Watchdog time-out is 2
and RWT bits are protected by the Timed Access procedure. This prevents software from accidentally
enabling or disabling the watchdog timer. More importantly, it makes it highly improbable that errant
code can enable or disable the watchdog timer. Please refer as below demo program.
bypass_reset:
watchdog timer. If the Watchdog interrupt is enabled (EIE.4), then an interrupt will occur (if the
global interrupt enable is set and other interrupt requirements are met). Software or any reset
can clear this bit.
This bit is useful for determined the cause of a reset. Software must read it, and clear it
manually. A Power-fail reset will clear this bit. If EWT = 0, then this bit will not be affected by
the watchdog timer.
leave the timer running.
restart it. This bit is self-clearing, so after the software writes 1 to it the hardware will
automatically clear it. If the Watchdog timer reset is enabled, then the RWT has to be set by
the user within 512 clocks of the time-out. If this is not done then a Watchdog timer reset will
occur.
timer reset function. Setting this bit to 0 will disable the Watchdog timer reset function, but will
org
mov
mov
clr
jnb
jmp
mov
mov
setb
reti
org
out interval for the watchdog timer. The reset time is 512 clock longer than the interrupt
time-out value.
300h
TA,#AAH
TA,#55H
63h
WDIF
execute_reset_flag,bypass_reset
$
TA,#AAH
TA,#55H
RWT
17
clocks, which is the shortest time-out period. The EWT, WDIF
- 48 -
; Test if CPU need to reset.
; Wait to reset
W79E532/W79L532