Octagon 6000 Series, User Manual

Page: 130 / 233

16-1
6000 Series user’s manual Watchdog timer, reset, and remote reset
Chapter 16:
Watchdog timer, reset, and
remote reset
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Watchdog timer
The watchdog timer is a fail-safe against program crashes or processor
lockups. It times out every 1.6 seconds (1.6 sec. typical, 1.00 sec. min.,
2.25 sec. max.) unless it is disabled or strobed by the software. The
watchdog timer can be controlled through the enhanced INT 17H inter-
face which is a built-in function on the PC Microcontroller.
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Enhanced INT 17H function definitions
This section provides definitions for the following functions: Enable
Watchdog, Strobe Watchdog, and Disable Watchdog.
Enable watchdog
Function: fdh
Subfunction: 01h
Purpose: To enable the watchdog.
Calling registers: AH fdh
AL 01h
DX ffffh
Return registers: None
Comments: This function enables the watchdog. Once the watchdog
is enabled, it has to be strobed at a period of not less than
1.6 seconds or until the watchdog is disabled. Otherwise,
a system reset will occur.
Programming example:
/* Inline assembly code for Borland C++ 3.1 */
asm {
mov ax,0fd01h
mov dx,0ffffh
int 17h
}