Eurotech CPU-1474, Руководство пользователя, Страница: 42 / 50

Configure the Watchdog timer
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Configure the Watchdog timer
The Watchdog Timer is a computer hardware countdown that triggers the board reset if the main
program, due to some fault condition, such as a hang, neglects to regularly refresh the watchdog. The
intention is to bring the system back from the unresponsive state into normal operation.
NOTE:
In the CPU-1474/84 the watchdog is a part of the on–board SUPER I/O device PC87364
The Super I/O registers allow you to manage time-outs in order of seconds or minutes, depending on
the Super I/O programming.
EXAMPLE: How to change the Super I/O (SPIO) PC87364 Watchdog registers:
SPIO Watchdog base address:
IO_SPIO_WDT_BASE EQU 0840h
SPIOM_M_WD_ON MACRO
; Configure Watchdog Mask Register...
MOV DX,IO_SPIO_W00001h
IN AL,DX
AND AL,11110000b
OUT DX,AL
; Set Time Unit to Seconds...
MOV DX,IO_SPIO_W002h
IN AL,DX
AND AL,NOT 10000100b
OUT DX,AL
OR AL,10000000b
OUT DX,AL
OR AL,00000100b
OUT DX,AL
; Set Timeout to 2 Seconds...
MOV DX,IO_SPIO_WDT_BASE
MOV AL,2
OUT DX,AL
ENDM
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