On Mon, 25 Oct 1999 22:08:22 -0400 John Considine <jconsi@MAGICNET.NET>
writes:
> I am having a problem when I try to check the busy flag coming from
> the
> LCD display (BUSY_FLAG? subroutine shown below).  It is always busy

The PIC must read the data from the LCD while E is high.  The LCD returns
the data pins to tri-state as soon as E goes low.  Your program just
pulses E, the data has gone way by the time it reads it.  Rearrange to
something like:

        bsf     PORTA,E
        movfw   PORTB
        bcf     PORTB,E

Not that you're doing it here, but another common mistake is to hold E
high and read the data repeatedly.  The LCD will not change the data
output while E is high.  To find out when it becomes not busy you need to
pulse E for each read.
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