User guide

Magnum N270 Software Configuration
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Software Watchdog
The Magnum N270 has a built in Watchdog Timer. The Watchdog Timer (WDT) is a special hardware device
that monitors the computer system during normal operation. The WDT has a clock circuit that counts down
from a set number to zero. If a monitored item occurs before that timer reaches zero, the WDT resets and counts
down again. If for some reason the monitored item doesn’t occur before the timer reaches zero, the WDT
performs an action, such as a diagnostic operation (rebooting the computer) or generate an NMI. which can reset
the computer in cases where the System hangs or it stops working.
The timer can be initiated in BIOS or by software when the system boots. To initiate the Timer in BIOS
navigate to the Integrated Peripherals page
The Watchdog can be controlled by software program in the following manner
Watchdog Configuration
Address Port: 2Eh
Data Port: 2Fh
Description
87h
Unlock WDT
87h
“
07h
08h
Select Logic Device
30h
01h
Activate WDT
F5h
N
Set Second or minute: N=00h (second) N=08h (minute)
F6h
M
Set base timer as below
Watchdog counts down
F6h
M
Reset Timer
If Timer not reset, then WDT Timeout
30
00
Disable WDT
M=
N=00h
M=08h
00h
Time out Disable
Time out Disable
01h
Time out occurs after 1 second
Time out occurs after 1 minute
02h
Time out occurs after 2 seconds
Time out occurs after 2 minutes
......
......
......
FFh
Time out occurs after 255 seconds
Time out occurs after 255 minutes
Example (C):
The following example sets up the watchdog time to 5 minutes.
1. outportb(0x2e,0x87);
2. outportb(0x2e,0x87);
3. outportb(0x2e,0x07);
4. outportb(0x2f,0x08);
5. outportb(0x2e,0x30);
6. outportb(0x2f,0x01);
7. outportb(0x2e,0xF5);
8. outportb(0x2f,0x08);
9. outportb(0x2e,0xF6);
10. outportb(0x2f,0x05);
...
xx. outportb(0x2e,0xF6);
yy. outportb(0x2f,0x05);
...