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Wayne
Posts: 3
Hi MobiFlight community, I have been playing with mobiflight for a while now. I am trying to build an 737-800 autopilot panel. I want to use four 8 digit lcd displays. Is this possible? I am using two displays now and it is working.
Wayne
2019-07-10 02:32
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thatchi
Posts: 123
Yes. I use x4 8digit modules and split x2 to x4 4digit modules for course x2, heading and speed. The x2 8digit modules for altitude and vertical speed. You can do it easy if you got the modules with removable blocks of 4digit. You just pull out one of the 4digit block and hard wire to the socket pin by pin. Here my prototype 737 mcp.

There 3digit left of altitude, I use 5digit for altitude, and I use the first 2digit to display flap from 0 to 40, third digit empty , last 5digit for altitude.
Same for v/s. First 5digit for v/s. last 3digit for gear position , x3 for left nose right gear. You can do trick to display gear as --- (x3 dash) for up and ___(x3 underscore) for down. That way I got all indicators I want using x4 8digit modules.
By the way, the mcp on top is my prototype for a320 using x2 LCD 1602.
Sorry my pict is upside down. :)
2019-07-10 07:44
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thatchi
Posts: 123
OK. My pict now is right side up. Another point when using multiple led modules. You should wire each vcc pin of each modules directly to +5v to avoid voltage drop in the last few modules. Good luck.
2019-07-10 07:52
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pizman82
Moderator
From: ETSI, Germany
Posts: 2735
Supporter
Thatchi already awnser your question and give you the important "5v -Single wire" information.

Just to complete this let me say it is also possible to build individual Displays . If you use the MaxTubes with removeable Diggits you can buy 3 Digit Displays and 5 Digit displays also..... then you have a "perfect" Optic.

Finaly it is also possible to directly work with MaxChips (without that Tube PCB ) ..... But here we talk about advanced systems with self designed PCB´s.

So i recommend..... Order some Max Tubes (removeable) and experiment a bit..... Solder 12 wires on the empty pins and "extend" the lines to a 1x4 Block for 40cm ..... Then you understand the logic ..... If you now use a 3 Digit Display instead then you just use 11 wires instead 12 . If you build a 5 Digit Dsiplay you increase number of wires to 13 and use also a Pin of the Other MaxBlock on the opposit side.

Summary.... Wire premade Digit Blocks is no problem..... Just learning of Pinsystem and some solder-skills are needed. ----- Building high professional Displays with 1 digit single Displays on selbuild PCB with Onboard Max-Chips is "perfect" but also advanced and need a lot of knowledge and equipment !
Good Luck !
2019-07-11 03:22
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Wayne
Posts: 3
Thanks for your help. My next question is are you using the 5V from the arduino or an external supply to run the LCDs.
Wayne.
PS I love your work, my wife thinks I am little bit over the top.
2019-07-11 03:48
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pizman82
Moderator
From: ETSI, Germany
Posts: 2735
Supporter
Here i´m not professional.....

Basicly i think its possible to do this with external suply..... But its not needed. In Case Max Chips work with low electrical power its no problem to use onboard 5v power.

Whatever i recommend basicly to split power as good as possible..... If you need in your project lots of LED, Displays Switches and so on then plan it in a balanced way....
So NOT put all inputs to Board A and all Outputs to Board B and all Displays to Board C e.g.
Also if you need already 3 Megas in a Element and 6 Displays then maby use 2 Displays each.
Whatever its possible to build a chain with 8 Displays.... this Increase the data transfer extremly.... If you build 4 Lines with 2 Displays optical result is the same but CPU usage is reduced.

In easy words.... Mix In and Outputs and split Displays over multiple Megas if you already need more then one in the same area.
Good Luck !
2019-07-11 07:39
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thatchi
Posts: 123
Each USB port can supply 5v at 500 mA max. Both my mcp got power from USB port. :thumbup:
2019-07-11 07:54
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Wayne
Posts: 3
Thanks for the help. I now have four 8 digit lcd running and and working on fsx. Must have been some dodgy wireing on my behalf. I have ordered some lcds with bases so I will do some testing when they arrive.When I get started on the face panel I will send a photo. thanks again.
Wayne:thumbup:
2019-07-11 09:34
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