Section Five
Programming the GPIB-LPT
© National Instruments Corporation
5-9
GPIB-LPT User Manual
g. Set the signal STROBE equal to 0.
h. Increment the data pointer.
i.
Return from the routine.
Timing Constraints
When writing to or from a driver, it is important to meet all timing constraints. The only
constraint for the GPIB-LPT is the length of the STROBE pulse. The following sequence
guarantees a pulse width between 1 and 5
µ
sec:
mov al,0Dh
;STROBE mask
mov dx,CTRL
;dx points to the CTRL register
cli
;disable interrupts to prevent
;stretching of the pulse
out dx,al
;set STROBE=1
jmp $+2
;delay to meet timing
jmp $+2
;requirement
mov al,0Ch
;normal mask
out dx,al
;set STROBE=0
sti
;interrupts back on
Note: Interrupts are turned off so that the pulse is not interrupted and stretched.