Dual LCD Display - Electronic Circuits Projects Diagrams Free

Lighty · 6th November 2009, 09:56 PM

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 · 7th November 2009, 12:35 AM

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 · 7th November 2009, 10:56 AM

Ok Atomsoft

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

Pommie · 7th November 2009, 11:03 AM

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 · 7th November 2009, 02:01 PM

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

Pommie · 7th November 2009, 02:06 PM

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 · 7th November 2009, 02:23 PM

cool now i know heh

Mr RB · 7th November 2009, 03:13 PM

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 · 7th November 2009, 03:40 PM

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 · 7th November 2009, 03:47 PM

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 · 7th November 2009, 03:59 PM

Cool Thx Pommie

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6th November 2009, 09:56 PM	#1
Lighty	Dual LCD Display 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!

7th November 2009, 12:35 AM	#2
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 __________________ AtomSofts eBay Store AtomSoftTech: C18 TIPS & TRICKS v9 PDF Nokia 6100 Driver/Software My Name: Jason Lopez http://atomsofttech.info/ \| My YouTube Videos! My Favorite Store: dipmicro Electronics Last edited by AtomSoft; 7th November 2009 at 12:49 AM.

7th November 2009, 10:56 AM	#3
Lighty	Ok Atomsoft So I assume you can't just parallel the connections?

7th November 2009, 11:03 AM	#4
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. Last edited by Pommie; 7th November 2009 at 11:04 AM.

7th November 2009, 02:01 PM	#5
AtomSoft	pommie you dont think it will draw to much current from LCD? Im not sure but heh i never tried or checked. __________________ AtomSofts eBay Store AtomSoftTech: C18 TIPS & TRICKS v9 PDF Nokia 6100 Driver/Software My Name: Jason Lopez http://atomsofttech.info/ \| My YouTube Videos! My Favorite Store: dipmicro Electronics

7th November 2009, 02:06 PM	#6
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.

7th November 2009, 02:23 PM	#7
AtomSoft	cool now i know heh __________________ AtomSofts eBay Store AtomSoftTech: C18 TIPS & TRICKS v9 PDF Nokia 6100 Driver/Software My Name: Jason Lopez http://atomsofttech.info/ \| My YouTube Videos! My Favorite Store: dipmicro Electronics

7th November 2009, 03:13 PM	#8
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.

7th November 2009, 03:40 PM	#9
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........

7th November 2009, 03:47 PM	#10
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.