80C186EC/80C188EC Microprocessor User's Manual

TIMER/COUNTER UNIT
_CMPB equ word ptr[bp+6] ;get parameter off the stack
push ax ;save registers that will be
push dx ;modified
mov dx, T1CNT ;Clear Timer 1 Counter
xor ax, ax
out dx, al
mov dx, T1CMPA ;set time before t_shot to 0
mov ax, 1
out dx, al
mov dx, T1CMPB ;set pulse time
mov ax, _CMPB
out dx, al
mov dx, T1CON
mov ax, C002H ;start Timer 1
out dx, al
CountDown: in ax, dx ;read in T1CON
test ax, MaxCount ;max count occurred
jz CountDown ;no: then wait
and ax, not MaxCount ;clear max count bit
out dx, al ;update T1CON
pop dx ;restore saved registers
pop ax
pop bp ;restore caller’s bp
ret
_one_shot endp
lib_80186 ends
end
Example 9-3. Configuring a Digital One-Shot (Continued)
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