68
MOV
AL, 55h
; SPIO Configuration Mode Enable Key
OUT
DX, AL
; Enter in configuration mode
; Select Logical Device 8 (watch dog) ...
MOV
DX, 3F0h
; SPIO Index Port
MOV
AL, 07h
; Logical Device selector is the register 7
OUT
DX, AL
; Point to Logical Device selector
INC
DX
;
SPIO
Data
Port
MOV
AL, 08h
; Logical Device number 8
OUT
DX, AL
; Select the Logical Device 8
; Select the time base (seconds or minutes) ...
MOV
DX, 3F0h
; SPIO Index Port
MOV
AL, F1h
; Watchdog timer units register (WDT_UNITS)
OUT
DX, AL
; Point to register WDT_UNITS
INC
DX
;
SPIO
Data
Port
IN
AL,
DX
;
Read
WDT_UNITS
OR
AL, 01h
; Mask reserved bits and set time in seconds
;
AND AL, FEh
; Mask reserved bits and set time in minutes
MOV
BL, AL
; Save new WDT_UNITS value
MOV
DX, 3F0h
; SPIO Index Port
MOV
AL, F1h
; Watchdog timer units register (WDT_UNITS)
OUT
DX, AL
; Point to register WDT_UNITS
INC
DX
;
SPIO
Data
Port
MOV
AL,
BL
;
WDT_UNITS
value
OUT
DX, AL
; Write the new WDT_UNITS value
; Select the watchdog timer timeout value ...
MOV
DX, 3F0h
; SPIO Index Port
MOV
AL, F2h
; Watchdog timeout value (WDT_VAL)
OUT
DX, AL
; Point to register WDT_ VAL
INC
DX
;
SPIO
Data
Port
MOV AX, 37
; New WDT_ VAL value (from 0 to 255 - seconds in this
case)
OUT
DX, AL
; Write the new WDT_ VAL value
; SPIO: exit from configuration mode ...
MOV
DX, 3F0h
; SPIO Index Port
MOV
AL, 0AAh
; SPIO Configuration Mode Disable Key
OUT
DX, AL
; Exit from configuration mode
•
Note:
for further information about the watchdog programming, refer to
“FDC 37B78x
Advance Information”
manual from
SMSC
.
