PCM-C418/Configuration
v1.0
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Page 17
6.6.1 Advanced
Enable the watchdog timer in the BIOS Settings by entering a value for Watchdog
Timeout on the Chipset > SouthBridge Configuration screen. When the operating
system is loaded, disable or reconfigure the watchdog in the application software.
NOTE
WinSystems recommends using a long timeout if the watchdog is enabled when trying
to boot any operating system.
Enable, disable, or reset the watchdog by writing the appropriate values to the
configuration registers located at I/O addresses 565h and 566h. Enable the watchdog by
writing a timeout value other than zero to the I/O address 566h and disable it by writing
00h to this I/O address. Service the watchdog timer by writing the desired timeout value
to I/O port 566h. If the watchdog has not been serviced within the allotted time, the
circuit resets the CPU.
Set the timeout value from 1 second to 255 minutes. If port 565h bit 7 equals
0
, the
timeout value written into I/O address 566h is in minutes. The timeout value written to
address 566h is in seconds if port 565 bit 7 equals
1
.
6.6.2 Legacy
Software watchdog timer PET = PORT 566H, write the timeout value.
The Legacy watchdog timer interface is provided for legacy software support only and is
not recommended for new development.
Enable or disable the watchdog via software by writing an appropriate timeout value to
I/O port 1EEH. See the chart provided below.
Table 9:
Watchdog timer examples
Port Address Port Bit 7 Value Port Address
Value
Reset Interval
565H
x
566H
00h
Disabled
565H
1
566H
03h
3 seconds
565H
1
566H
1Eh
30 seconds
565H
0
566H
04h
4 minutes
565H
0
566H
05h
5 minutes
Table 10:
Timeout values
Port Address
Value
Reset Interval
1EEH
00h
01h
Disabled
2 seconds
1EFH
Any
Reset timer
