Maximun Cable Length for PIC to LCD

[wildbilly]

Thank you KVLV. I think you are correct about using serial instead. It would be nice though to be able to use the parallel interface. I do enjoy a challenge and it keeps PicBasic interesting.
Thanks Darrel, I have read the LCD_Anypin thread and that is very interesting. I am up for the leg work. I am willing to try and I will do all the testing required.

Thank you.

[Darrel Taylor]

I am up for the leg work. I am willing to try and I will do all the testing required.

Shouldn't take much, but you'll need to install the HighJack routines first.
And you'll also be using the LCD_Anypin files, so download them too.

Start with that, and you should be able to get the LCD working on a Short cable first.

After that, we'll adjust the delays and see what happens on a long one.
If you have any problems getting LCD_Anypin to work, let me know.
<br>

[w7ami]

wildbilly,

It should be possible to send data over 20 feet to your display and have it work, but not using ribbon cable. All the conductors are parallel to each other and divided by insulation. In other words you have a bunch of capacitve coupling between the lines. Also the ribbon cable is likely not shielded so any manner of garbage will be picked up from the nearby environment. I have an absolute encoder (10 lines of TTL data) working over a distance of 50 feet in a high RF environment.

First as stated earlier make sure you have cleaned up the power to the LCD with good bypass capacitors with short lead length. You will need to put the displays in some sort of metal box. Then use a shielded cable with twisted pairs (signal and ground on each pair) between the two units. Then if you are still having problems mess with the pulse widths.

Terry

[wildbilly]

Hello all. As W7AMI suggested, I have tried filtering the supply and I have changed the cable to shielded pairs but no luck. Darrel I have installed the Highjack routines and also included the LCD_Anypin.pbp and VirtualPort.bas in the PBP folder. I then added the Include file in my main program just below the define Parameters.

INCLUDE "LCD_AnyPin.pbp"
I am using MicroCode Studio and when compile is run I get the error
Line 87:Bad expression. (LCD-AnyPin.pbp)
The LCD_AnyPin file is opened and the line LOW LCD_RS : HIGH LCD_E is highlighted causing the error. I have included two images. The green Display is connected on the short cable and the Blue Display is connected to the long cable. As you can see blue is not displaying what the green is and the character on the blue display is constantly changing.

[Charles Linquis]

I think the problem is that it is just plain too cold where you live!

[wildbilly]

That's a good laugh. I thought someone would have that reply.

[Darrel Taylor]

Darrel I have installed the Highjack routines and also included the LCD_Anypin.pbp and VirtualPort.bas in the PBP folder. I then added the Include file in my main program just below the define Parameters.

Excellent!

Does your main program have this section (modified for your hardware of course).
The old lcd DEFINES can be commented out.

;----[ Change these to match your LCD ]---------------------------------------
</i></b></font><b>LCD_DB4   </b><font color="#008000"><b>VAR </b></font><b>PORTA</b>.<font color="#800000"><b>0
</b></font><b>LCD_DB5   </b><font color="#008000"><b>VAR </b></font><b>PORTB</b>.<font color="#800000"><b>3
</b></font><b>LCD_DB6   </b><font color="#008000"><b>VAR </b></font><b>PORTB</b>.<font color="#800000"><b>7
</b></font><b>LCD_DB7   </b><font color="#008000"><b>VAR </b></font><b>PORTC</b>.<font color="#800000"><b>1
</b></font><b>LCD_RS    </b><font color="#008000"><b>VAR </b></font><b>PORTD</b>.<font color="#800000"><b>4
</b></font><b>LCD_E     </b><font color="#008000"><b>VAR </b></font><b>PORTA</b>.<font color="#800000"><b>1
</b></font><b>LCD_Lines     </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>2    </b></font><font color="#0000FF"><b><i>' # of Lines on LCD,  1 or 2 (Note: use 2 for 4 lines)
</i></b></font><b>LCD_DATAUS    </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>50   </b></font><font color="#0000FF"><b><i>' Data delay time in us 
</i></b></font><b>LCD_COMMANDUS </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>2000 </b></font><font color="#0000FF"><b><i>' Command delay time in us 

</i></b></font><font color="#008000"><b>INCLUDE </b></font><font color="#FF0000">&quot;LCD_AnyPin.pbp&quot;  </font><font color="#0000FF"><b><i>; *** Include MUST be AFTER LCD Pin assignments ****</i></b></font>