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Appendix A. Watchdog Timer
The Watchdog Timer is a device to ensure that
standalone systems can always recover from
catastrophic conditions that cause the CPU to crash.
This condition may have occurred by external EMI or
a software bug. When the CPU stops working
normally, hardware on the board will perform
hardware reset (cold boot) to bring the system back
to a known state.
Three I/O ports control the Watchdog Timer.
443
Write
Set Watchdog Time period
443
(hex)
Read
Enable the refresh the Watchdog Timer
043/843
(hex)
Read
Disable the Watchdog Timer
Prior to enable the Watchdog Timer, user has to
define Timer first. The output data is a value of time
interval and the range of the value is from 01(hex) to
FF (hex) and time interval 1 sec to 255 sec.
Data Time Interval
01
1 sec
02
2 sec
03
3 sec
04
4 sec
.
.
.
.
.
.
FF
255 sec
Summary of Contents for WAFER-5821
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