Multiplexing data pins for two LCDs and LCD programming

firestorm.v1

While experimenting with an LCD display, I noticed that there are a total of 6 data pins, and two control pins (Register Select and Enable)

With the exception of the R/S and the E pins has anyone tried to use the same data pins but pulsing out either of the two control pins?

Wiring diagram:

P0 - "E" pin of LCD1
P1 - "RS" pin of LCD1
P2 - "RW" pin of LCD1
P3 - "E pin of LCD2
P4 - "RS pin of LCD2
P5 - "RW pin of LCD2
P6-P9 Data to both LCDs.

Additionally, does anyone know of example code that demonstrates how to program specific characters into the LCD display? I understand that there is a certain order in which the pins have to be setup and that it is done in hex but aside from that and the use of the character generator app available on the parallax site, I'm kinda clueless. Any tips?

Thank you.

Jon Williams

You can use the data buss pins as inputs; have a look at our LCD Terminal AppMod docs:

http://www.parallax.com/dl/docs/prod/appmod/LcdTerminal.pdf

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Jon Williams
Applications Engineer, Parallax

rockin_rick

While I've never tried it, I would think that you would only need to use seperate enable (E) lines, and all the others could be bussed together (including R/S and R/W). IOW - adding a second LCD would only take 1 more line...


Rick

Jon Williams

I agree with Rick -- so long as the E line is not mistreated -- and you appropriately protect the other I/O pins -- you can do lots of neat tricks; at the cost of a bit of code, of course.

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Jon Williams
Applications Engineer, Parallax

firestorm.v1

Thank you both for your help. I was able to pull off the code and my project is in the "Projects" section of the forum:
http://forums.parallax.com/forums/default.aspx?f=21&m=118073