Nexcom PEAK 7220VL2G User Manual page 61

B.3.2 Clear the WDT
WDT counter interval cannot be longer than the preset time, otherwise, WDT sends a
reset signal to the system.
The following is an example of clearing the WDT program in Intel 8086 assembly
language.
; ( Clear the WDT)
Mov dx, F2h ;Setting the WDT configuration port
In al, dx
Note: Before running WDT, you must clear WDT to ensure
that the initial value is zero.
B.3.3 WDT Control Register
Note: This register writes to WDT configuration port.
Set WDT Control Register to control the WDT working mode. The initial value of
WDT Control Register is shown as follows:
; (Setting the WDT Control Register as AL)
Mov al, 0h ; Setting initial value = 0 for the WDT Control Register
Follow these instructions to set the register:
1. Select the time-out intervals of WDT (decide the values of D2, D1, D0 in F2 )
Example: If D2~D0 = 0, the time-out interval is 64 seconds.
AND al, 11111000b ; Setting the time-out interval as 64 sec.
2. Enable or Disable WDT ( decide D3 value in F2)
i.e. D3=0, Disables WDT
AND al, 11110111b ; Disable the WDT
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