WIN Enterprises MB-73030, Руководство пользователя

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Appendix A: Programming the Watchdog Timer
The MB-73030 provides a watchdog timer that resets the CPU or generates an interrupt
if processing comes to a stop. This function ensures greater system reliability in
industrial stand-alone and unmanned environments.
In order to enable the watchdog timer, you have to output the value of the watchdog
timer interval to the controller. The value range is from 01H to FFH, and the related time
watchdog timer interval is 1 sec to 255 sec.
Data Timer interval
00 Disabled
01 1
sec
02 2 sec
* *
* *
FF 255
sec
If you want to disable the watchdog timer, just set the timer interval value to 00H.
After setting the timer interval value, the watchdog timer begins to count down. You have
to refresh the watchdog timer, so that the watchdog timer will return to its initial value;
otherwise, your system will reset after a time-out. The following program shows how to
set the watchdog timer:
ASSEMBLY LANGUAGE DOS DEBUG
Program 1: Initializing the watchdog controller
MOV DX,2EH
MOV AL,87H
OUT DX,AL
OUT DX,AL O 2E 87
O 2E 87
MOV DX,2EH
MOV AL,07H
OUT DX,AL
MOV DX,2FH
MOV AL,08H
OUT DX,AL O 2E 07
O 2F 08
MOV DX,2EH
MOV AL,30H
OUT DX,AL
MOV DX,2FH
MOV AL,01H
OUT DX,AL O 2E 30
O 2F 01