
W925E/C625
8-bit CID Microcontroller
Revision : A6
-29-
Release Date : 2002/7/2
WATCHDOG CONTROL
(initial: note)
Bit:
7
-
6
5
-
4
3
2
1
0
POR
WFS
WDIF
WTRF
EWT
RWT
Mnemonic: WDCON
Address: D8h
POR: Power-on reset flag. Hardware will set this flag when system is powered on and this flag is
cleared only by software.
WFS: Watchdog Timer Frequency Select. Set to select F
S
as WDT clock input. Clear to select
F
OSC
as WDT clock input.
WDIF: Watchdog Timer Interrupt flag. This bit is set whenever the time-out occurs in the
watchdog timer. If the Watchdog interrupt is enabled (EIE.5), 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.
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
effect
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
known
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.5) 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.
Note:
The WDCON SFR is set to a 0x000xx0b 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.
ACCUMULATOR
(initial=00H)
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 ACC register.
EXTENDED INTERRUPT ENABLE
(initial=00H)
Bit:
7
-
6
-
5
4
3
2
1
0
EWDI ECOMP
EDIV
ECID
EX3
EX2
EIE.7-6:Reserved bits
.
EWDI: Enable Watchdog timer interrupt.
ECOMP: Enable comparator interrupt.
EDIV: Enable Divider interrupt.
ECID: Enable CID interrupt.
EX3: Enable External Interrupt 3.
EX2: Enable External Interrupt 2.
Mnemonic: EIE
Address: E8h