Watchdog function definitions using enhanced INT 17h handler
This section provides definitions for the watchdog functions using the INT17
handler, stored in the extended BIOS area that is enabled by the X jumper, or the
I17HNDLR.EXE utility. I17HNDLR.EXE is a TSR program. Once executed it is
active, but it must be executed each time the system is rebooted. If you use a
different BIOS, the INT17 functions can still be used by your application. Copy the
I17HNDLR.EXE utility to your hard drive and add it to your AUTOEXEC.BAT.
The INT17 handler is designed for DOS based applications. If you use a different
operating system and the watchdog functions are required for your application,
source code is available on the Octagon Product CD-ROM to access the watchdog.
OS Development Kits are available from Octagon for Linux, QNX, and Windows
CE.net that have watchdog drivers for these operating systems. Contact Octagon
Systems for more information.
Enable watchdog
Function: fdh
Subfunction: 01h
Purpose:
To enable the watchdog.
Calling registers:
AH
fdh
AL
01h
BX
timeout (0=2 ms, 1=20 ms, 2=60 ms,
3=200 ms, 4=2 s, 5=20 s, 6=120 s, 7=na)
DX
ffffh
Return registers:
None
Comments:
This function enables the watchdog. Once
the watchdog is enabled, it has to be strobed at
least twice per timeout period specified or until
the watchdog is disabled. Otherwise, a system
reset will occur.
Programming example:
/* Inline assembly code for Borland C++ 3.1 */
/* set watchdog to two second timeout */
asm {
mov
ax,0fd01h
mov
bx,4
mov
dx,0ffffh
int
17h
}
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