I didn't get any response, so I will try again.  Sorry if someone responded
and I didn't receive it.  After reading the post, I may have seemed a little
angry (actually I was extremely frustrated). ;-D  But surely someone here
uses 8051-type processors and BASCOM51.

UPDATE:

I finally got the Toshiba TLX-1741-C3M (6939C based) LCD display working
(more or less).  Man these things are way faster than the little 1/2/4 line
Hitachi based displays.  You can issue commands as fast as the processor is
capable (well cut's anyway).  The longest wait time (according to datasheet)
is 150ns.  I have text mode working fine, but I can't seem to read the
display.

QUESTION:

Does anyone know how to make BASCOM51 read P2.  This SBC I'm using only
leaves P0 and P2 available.  P1 and P3 are pretty much tied up with on-board
uses.  THERE IS NO EXTERNAL MEMORY SO I AM USING THESE PORTS.  ;-)  I'm
using P0 to drive the CE/RD/WR/CD/FS/RV control lines.  P2 is connected to
D0-D7 of the display.  I am having no problems when writing characters to
the display.  The problem is reading the display.  Whenever I use a
statement like "Status = P2" when checking status, I only seem to receive
the latch contents (IOW whatever I wrote last).  Is there some trick in
BASCOM51 to read the port pins and not the latch.  I am moving 0xFF to the
port (like the datasheet says) before reading the port.  All I receive back
is the 0xFF, but I know that can't be right since the display is working in
receive mode.  Below is a code snippet of the status reading routine.  Even
the 1ms delay doesn't help.

 P2 = &H0FF   'make port 2 input
 set P0.0    '/WR high
 set P0.3    '/CD high
 reset P0.1  '/RD low
 reset P0.2  '/CE low
 waitms 1
 StatusByte = P2
 set   P0.2  '/CE high
 y = StatusByte And &H003

If someone could help, I'd sure appreciate it.  I am a novice at the 8051
architecture, but I'm trying to learn.  ;-)  I'm currently re-writing the
program in SDCC (and everyone thinks C is just C).  This way, I can verify
that P2 is, in fact, returning the wrong value.  It could be that the
outputs of the display are not strong enough to pull down the internal uC
pull-ups.  8052 ports seem to be much like the open-collector ouput on the
PIC, but with strong internal pull-ups.

Michael Brown
Instant Net Solutions
www.KillerPCs.net

"In the land of the blind, he who has one eye is king"


Michael Brown
Instant Net Solutions
www.KillerPCs.net

"In the land of the blind, he who has one eye is king"

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