Watch Dog Timer Programming Procedure - Nexcom PEAK 6320A User Manual

PEAK 6320A Series User's Guide

Watch Dog Timer Programming Procedure

• Power on or reset the system
The initial value of WDT Control Register (D4~D0) is zero, when power is on or reset the
system. The following means the initial value of WDT ( 00000000b ) :
Bit Value Mean
4 0 Select Reset
3 0 Disable watch dog timer
2, 1, 0 0 0 0 Select 64 second
• Initialize the SQW of RTC (set SQW output period=0.5 second)
To initialize the SQW of RTC processor is to set the SQW signal which is output
period=0.5 second. It offers the basic frequency of the WDT counter.
The following is an example of initializing the SQW signal program in Intel 8086
assembly language.
; (Generate SQW = 0.5 Sec.)
Mov dx, 70h
Mov ax, 0Ah
Out dx, al
Mov dx, 71h
Mov ax, 2Fh
Out dx, al
; (enable the SQW output)
Mov dx, 70h
Mov ax, 0Bh
Out dx, al
Mov dx, 71h
Mov ax, 0Ah
Out dx, al
Watch Dog Timer
; Out port 70h = 0Ah
; Out port 71h = 2Fh
; Out port 70h = 0Bh
; Out port 71h = 0Ah
A1-3