TheBackShed.com

Forum Index : Microcontroller and PC projects : Driving two LCD’s from an E100...

Page 2 of 3

Author

Message

CaptainBoing

Guru

Joined: 07/09/2016
Location: United Kingdom
Posts: 2170

Posted: 09:09am 30 Jun 2018

Copy link to clipboard

Print this post

"confirmed"

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 09:13am 30 Jun 2018

Copy link to clipboard

Print this post

"What are they?!"
"Unfriendly, which is fortunate really, they'd be difficult to love."

Smoke makes things work. When the smoke gets out, it stops!

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 09:24am 30 Jun 2018

Copy link to clipboard

Print this post

"Which really only leaves one question: Is it that Blake has a genius for leadership, or mealy that YOU have a genius for being led."

.....so many great quotes.

Sorry, I digress.

Smoke makes things work. When the smoke gets out, it stops!

Azure

Guru

Joined: 09/11/2017
Location: Australia
Posts: 446

Posted: 12:35pm 30 Jun 2018

Copy link to clipboard

Print this post

Dpn't want to be a bubble burster, however:

I don't think you'll be able to run a high speed parallel bus that far (reliably).
It's not a terminated line with balanced impedance. So you will get reflections corrupting things and some signals arriving before other over that length. Since it is not point to point (it is multidrop) you will get multiple reflection points.
It is not the same as the parallel data lines that run around and even connect to the board in close proximity to each other. Then there is also the noise the cable will generate and receive as a large antenna.

I thought you would use the serial interface.

Anyway, give it try, it can only not work. And I am happy for you to use Murphy to prove the rules of parallel buses wrong.

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 11:39pm 30 Jun 2018

Copy link to clipboard

Print this post

G'Day all
Where did this long parallel bus come from?
Did I miss something?

Peter

Chopperp

Guru

Joined: 03/01/2018
Location: Australia
Posts: 1097

Posted: 12:12am 01 Jul 2018

Copy link to clipboard

Print this post

I think they're talking about using a parallel type display on a longish cable. But I could be wrong.

ChopperP

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 12:52am 01 Jul 2018

Copy link to clipboard

Print this post

I understood from Grogster's description the displays would be back to back in one housing, so short leads. How data got there was not part of the problem.
Is this an OOPS moment?

Peter

Azure

Guru

Joined: 09/11/2017
Location: Australia
Posts: 446

Posted: 02:50am 01 Jul 2018

Copy link to clipboard

Print this post

PeterB said G'Day all
Where did this long parallel bus come from?
Did I miss something?

Peter

Sorry, could be my interpretation, I assumed these were not back to back but spaced apart.

If they are back to back and cable between them and the controller board is kept neat and short then it should be in with a good chance.

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 03:05am 01 Jul 2018

Copy link to clipboard

Print this post

Sorry for any confusion on cable length etc.

Back to back within close proximity to each other. Shortest cable possible, and would probably use an old 40-way IDE HDD lead if the experiment worked. BOTH displays inside the one enclosure, with one LCD facing one way, the other LCD facing the other way.

Certainly NOT trying to run the parallel bus to the LCD's down the hallway or anything like that.

Azure's comments about being concerned about that are totally valid if this was what I was going to do, but definitely not.

Smoke makes things work. When the smoke gets out, it stops!

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 03:26am 01 Jul 2018

Copy link to clipboard

Print this post

PHEW

Peter

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 03:38am 01 Jul 2018

Copy link to clipboard

Print this post

Little update: I put an E100 and 5" LCD on a 40-way IDE hard-drive cable, and the screen fails to initialize, and the SD card is completely unresponsive. Put the LCD back on the E100, everything works fine.

I might be pushing things a little with this idea. I might rethink along the lines suggested by OA47 of having two E100+LCD's in the same case in order to save my sanity. At least I know that should work. Coupling multiple displays might be a recipe for disaster.

Smoke makes things work. When the smoke gets out, it stops!

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 03:50am 01 Jul 2018

Copy link to clipboard

Print this post

Perhaps I should rethink this along the lines of a CMM or an MMX and use the VGA output, then I can split that output to two cheap LCD displays.

Three bucks fifty for a VGA splitter cable, and a couple of these 7" LCD units?

Hmmmmmmmm........

Smoke makes things work. When the smoke gets out, it stops!

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 04:26am 01 Jul 2018

Copy link to clipboard

Print this post

Two questions.
How long is that cable and how confident are you in it?

Peter

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 04:35am 01 Jul 2018

Copy link to clipboard

Print this post

Pretty confident. Standard IDE cable length. About 350mm end to end, three 40-pin connectors on it. I will see if I can find another IDE lead just to be sure. I used to have bins full of them, but most of them got biffed once SATA was the new HDD standard.

Smoke makes things work. When the smoke gets out, it stops!

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 05:23am 01 Jul 2018

Copy link to clipboard

Print this post

I have a 7in display connected to a E100 via a 150mm cable.
No probs.

Peter

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 07:01am 01 Jul 2018

Copy link to clipboard

Print this post

Yeah, you may well, and that might work just fine. I suspect that 350mm is just too long. Thinking about options.....

Smoke makes things work. When the smoke gets out, it stops!

Quazee137

Guru

Joined: 07/08/2016
Location: United States
Posts: 593

Posted: 11:18am 01 Jul 2018

Copy link to clipboard

Print this post

Haven't used the E100 so not sure if using composite to drive two

of the cheap backup camera displays like this.

5" backup LCD

I am using a 4.3" with the dinomite mini and a backup camera. Most of the backup
displays I looked at had two inputs. Some controlled by a backup lamp connection
others by a signal. You could watch video from input two until the backup camera
fired up on input one.

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 05:21am 14 Jul 2018

Copy link to clipboard

Print this post

G'Day Grogster et al

I know this is a bit late but my new 7in display only arrived yesterday.
As predicted, it is possible to drive two 7in displays from an E100 over a 150mm cable.
I tried a 1m cable with no luck. The wave-forms look dreadful but then they do over any cable so perhaps I need to learn how to drive my DSO. I never did trust these DSO things.

Peter

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 05:29am 14 Jul 2018

Copy link to clipboard

Print this post

Awesome!

Thanks for posting. I still had not decided what I was doing there, so this is VERY useful information to me. Were you just using an old IDE hard-drive lead or something else? I could not make my attempt work with an old IDE lead.

Smoke makes things work. When the smoke gets out, it stops!

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 05:48am 14 Jul 2018

Copy link to clipboard

Print this post

I'm not sure where the 150mm cable came from. I do remember cutting it but I have made cables as required so it could be anything. All you need is a 4 inch Dawn vice to make one. The connectors and cable come from Aztronics / Altronics ebay Jaycar.
The important thing to remember is:

THE E100 IS INDESTRUCTABLE
THE DISPLAY IS INDESTRUCTABLE

I know because I have plugged them in every which way.

I need to do more work on what happens over a lomger cable.

Peter

Page 2 of 3

Print this page