Instruction Manual
Preliminary W79E8213/W79E8213R Data Sheet
Publication Release Date: July 11, 2008
- 31 - Revision A2
Continued
BIT NAME FUNCTION
2 WTRF
Watchdog Timer Reset Flag
1: 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 EWRST =
0, the watchdog timer will have no affect on this bit.
1 EWRST
0: Disable Watchdog Timer Reset.
1: Enable Watchdog Timer Reset.
0 WDCLR
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
EWRST 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 EWRST is set. This
WATCHDOG CONTROL
Bit: 7 6 5 4 3 2 1 0
WDRUN - WD1 WD0 WDIF WTRF EWRST WDCLR
Mnemonic: WDCON Address: D8h
BIT NAME FUNCTION
7 WDRUN
0: The Watchdog is stopped.
1: The Watchdog is running.
6 - Reserved.
5 WD1
4 WD0
Watchdog Timer Time-out Select bits. These bits determine the time-out period
of the watchdog timer. The reset time-out period is 512 clocks longer than the
watchdog time-out.
WD1 WD0 Interrupt time-out Reset time-out
0 0 2
17
2
17
+ 512
0 1 2
20
2
20
+ 512
1 0 2
23
2
23
+ 512
1 1 2
26
2
26
+ 512
3 WDIF
Watchdog Timer Interrupt Flag
0: If the interrupt is not enabled, then this bit indicates that the time-out period
has elapsed. This bit must be cleared by software.
1: If the watchdog interrupt is enabled, hardware will set this bit to indicate that
the watchdog interrupt has occurred.
2 WTRF
Watchdog Timer Reset Flag
1: 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 EWRST =
0, the watchdog timer will have no affect on this bit.
1 EWRST
0: Disable Watchdog Timer Reset.
1: Enable Watchdog Timer Reset.