W77E058A Datasheet, PDF (61/87 Pages) Winbond – 8-BIT MICROCONTROLLER

W77E058A
instructions to reset the watchdog timer which will allow the code to run without any watchdog timer
interrupts. Now the watchdog timer reset is enabled and the watchdog interrupt may be disabled. If
any errant code is executed now, then the reset watchdog timer instructions will not be executed at
the required instants and watchdog reset will occur.
The watchdog time-out selection will result in different time-out values depending on the clock speed.
The reset, when enabled, will occur 512 clocks after the time-out has occurred.
Table 9. Time-out values for the watchdog timer
WD1
0
0
1
1
WD0
0
1
0
1
WATCHDOG NUMBER OF
INTERVAL CLOCKS
2¹⁷
131072
2²⁰
1048576
2²³
8388608
2²⁶
67108864
TIME
@ 1.8432 MHZ
71.11 mS
568.89 mS
4551.11 mS
36408.88 mS
TIME
@ 10 MHZ
13.11 mS
104.86 mS
838.86 mS
6710.89 mS
TIME
@ 25 MHZ
5.24 mS
41.94 mS
335.54 mS
2684.35 mS
The Watchdog timer will de disabled by a power-on/fail reset. The Watchdog timer reset does not
disable the watchdog timer, but will restart it. In general, software should restart the timer to put it into
a known state.
The control bits that support the Watchdog timer are discussed below.
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Publication Release Date: April 17, 2007
Revision A10