W79E632A Datasheet, PDF (24/79 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E632A/W79L632A
WTRF: Watchdog Timer Reset Flag. Hardware will set this bit when the watchdog timer causes a
reset. Software can read it but must clear it manually. A power-fail reset will also clear the bit.
This bit helps software in determining the cause of a reset. If EWT = 0, the watchdog timer
will have no affect on this bit.
EWT: Enable Watchdog timer Reset. Setting this bit will enable the Watchdog timer Reset function.
RWT:
Reset Watchdog Timer. This bit helps in putting the watchdog timer into a know state. It also
helps in resetting the watchdog timer before a time-out occurs. Failing to set the EWT before
time-out will cause an interrupt, if EWDI (EIE.4) is set, and 512 clocks after that a watchdog
timer reset will be generated if EWT is set. This bit is self-clearing by hardware.
The WDCON SFR is set to a 0x0x0xx0b on an external reset. WTRF is set to a 1 on a Watchdog timer
reset, but to a 0 on power on/down resets. WTRF is not altered by an external reset. POR is set to 1 by a
power-on reset. EWT is set to 0 on a Power-on reset and unaffected by other resets.
All the bits in this SFR have unrestricted read access. POR, EWT, WDIF and RWT require Timed
Access procedure to write. The remaining bits have unrestricted write accesses. Please refer TA register
description.
TA
EG C7H
WDCON
REG D8H
CKCON
REG 8EH
MOV TA, #AAH
MOV TA, #55H
SETB WDCON.0
ORL CKCON, #11000000B
MOV TA, #AAH
MOV TA, #55H
ORL WDCON, #00000010B
; Reset watchdog timer
; Select 26 bits watchdog timer
; Enable watchdog
Accumulator
Bit:
7
6
5
4
3
2
1
0
ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0
Mnemonic: ACC
Address: E0h
ACC.7-0: The A (or ACC) register is the standard 8052 accumulator.
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