Dual LCD Display

[Lighty]

Hi

There is a project which I'm wanting to build that has a LCD display (4 bit), But was wondering if it is posible to run a second LCD a short distance for remote viewing (say less than 2 meters) from the same connection, putting it in parallel to the first?

Thanks in advance!

 

[AtomSoft]

I forgot a nice IC that would help u I'll look for it in a min

can't seem to remember... I would suggest using transistor to set low/high with pull up/down resistors

 

[Lighty]

Ok Atomsoft

So I assume you can't just parallel the connections?

 

[Pommie]

You can simply parallel the connections as long as you are using delays rather than reading the busy flag. If the R/W line is grounded then you are good to go. If the R/W is used then you could just ground the R/W line on the second display. If the later then make sure the displays are identical or the second one is a newer faster display.

Mike.

 

[AtomSoft]

pommie you dont think it will draw to much current from LCD? Im not sure but heh i never tried or checked.

 

[Pommie]

No, the control and data lines use no power whatsoever and so as long as your supply can power two LCDs then it will work fine. The only problem is if your second display is slower than your first (using R/W) but then you can just swap them over.

Mike.

 

[AtomSoft]

cool now i know heh

 

[Mr RB]

The LCD driver uses high impedance CMOS inputs (like Pommie said), you should be able to connect a LOT of paralleled LCDs to the PIC pins. You might increase the delays for safety in case you have added capacitance from long wires to the remote LCD.

 

[Lighty]

Thanks Guys

The the circuit does use the R/W, RS & E1 Pins

So just to confirm, the "remote" LCD should be "Faster" than the "main" LCD and the "remote" R/W should be grounded?

This is because the faster "Remote" LCD will process the data before the "main" LCD send a confirmation on the R/W pin to continue? Sorry, I'm a newbie on PICs nevermind LCDs.... LOL

If my understanding is correct, then would it not be better to make the "main" LCD faster and ground the R/W and rather use the slower remote LCD trigger the R/W, therefore making it safer as if there is any issues due to capacitance of long cabling the remote would always be last to process and trigger, and knowing the "main" would have finnished already? Hope that makes sense, but of cause it could only make sence if my above statement is true........

 

[Pommie]

You are correct in your assumptions, grounding the local LCD R/W would be safer. However, if you have the source code then I would just add a small delay after every write.

Mike.

 

[Lighty]

Cool Thx Pommie