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Apeshaft
Posts: 51
Supporter
Hello!

I've recently started to assemble my 737 OH.
I am looking for a good, not too expensive, solution for the electrical panel display on the fwd OH.
The real thing seems to be an alphanumeric display with green digits on a black background.
Would this be possible to simulate using a small color LCD display? Is it possible to do this using Prosim and/or PMDG?

Best regards

Oskar
2019-02-09 21:32
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StephanHo
From: EDDG, Germany
Posts: 1150
Supporter
Hi Oskar,

I do not use Prosim. But I think it should be possible if you can manipulate the LCD Background and Colour via Prosim.
This is not possible with Mobiflight.
Grüße,
Stephan
2019-02-10 01:02
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pizman82
Moderator
From: ETSI, Germany
Posts: 2264
Supporter
Hi
I also not use Prosim myself but get some experience while helping other users here.

For your situation its no mater if you use PMDG, ProSim or a other AddOn..... Cause NO addon itself can handle Hardware settings !
Basicly your AddOn only support the raw Data ( The Numbers that should be shown on Display ) PMDG do this... ProSim as i know, too.

What you now do with this Data is "your" problem.
For a 1:1 Solution you must use simmular Hardware.... In That case you must setup the Diggits ( Correct Color and size) and wire it to a Controller (Max7219)

Check this for example.... https://www.youtube.com/watch?v=ZnyuhxPnb_k
Its not needed to build a PCB (whatever its more comfortable and perfect) ... You can also build this with 2 Max7219 Chips and 50-120 single wires. ;)


But Sure your alternate is also possible.... In that case you must search in the shops for a LCD Display that is showing like you want AND Compatible to Mobiflight.
If you not need 100% real optic you can simply use a standard Display.... In that case the color and size is wrong.... But it work and show data !
Good Luck !
2019-02-10 05:57
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Apeshaft
Posts: 51
Supporter
Thank you for your answers!
I think that creating this using Max7219
and 100+ wires simply isn't a viable option for me.
Also I don't know how to design PCBs.
I have already got the green 7 segments so it would be really nice if I could put them to use.
I see that there exists a certain kind of pen now that can be used to draw conductive lines straight on to a prototype PCB. Perhaps this would be a possible solution for me.
2019-02-10 10:35
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Apeshaft
Posts: 51
Supporter
Hello again,

I might actually give PCB designing a try.

I found this online:

https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf

Would I be on the right path if I designed the same way as described in the section
"Serially Interfaced, 8-Digit LED Display Drivers" (only using a total of 15 digits).
I am currently doing a schematic sketch trough EasyEDA, would you guys be able
to look at when finished and give me your input?
2019-02-10 21:03
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StephanHo
From: EDDG, Germany
Posts: 1150
Supporter
Hi Apeshaft,

look here

https://www.ebay.com/itm/MAX7219-8-Digit-LED-Display-7-Segment-Digital-Tube-For-Arduino-Raspberry-Pi/201675752466?hash=item2ef4cfc412:m:mKmuLK1r53iChZwvgK69URQ:rk:1:pf:0

But note: if they ask for the colour they mean the colour of the PCB-board and not the colour of the LED-Tubes
This tubes are 9mm. But with this price you can buy smaller ones at other shops and wire them conventionally.
Grüße,
Stephan
2019-02-10 22:21
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Apeshaft
Posts: 51
Supporter
Hi Stephan, already got 10 or more of those, they are not very well suited for my project as I am using larger green coloured 7-segment displays which do not fit directly on these boards, meaning I am once again directed to using soldered on wires en masse.

I am hence looking for a neater and more integrated solution to this. Would appreciate if you could have a look at my link in my previous post and let me know what you think of it. I will later upload an image of my PCB schematic so you can give me your thoughts om on it.

Regards

Oskar
2019-02-10 22:52
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StephanHo
From: EDDG, Germany
Posts: 1150
Supporter
Hi Oskar,

you can use Tubes from every size, also normal single 7 segment digits. Ok, if you do not want to wire them and solder them on a PCB you need a static size ;)

Your link is the link to the MAX 7219 datasheet. I did not know where you live, but in Germany you pay nearly 6 Euros for a Max 7219 Chip plus the digits.

If you already have 10 boards, the only question is the color of the boards. If you have green ones, you can pull off the tubes, put new IC sockets on it and then wired the still to buy green digits with it. If you already have the boards, most of the work is already done. If the tubes are soldered it would be hard...

I like to look at your PCB and let you know my opinion.

But I would initially tend to make the conversion with the existing funds and thus to test. If you want to implement your original concept later, with more experiences, you can still do that.

If you do not get a green LED, take some light and make a green plexiglass slice in front of it.
Grüße,
Stephan
2019-02-10 23:23
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pizman82
Moderator
From: ETSI, Germany
Posts: 2264
Supporter
Hi Again

At fist it es nearly imposible to find a Display of your Choice ( 3 Diggit Green in correct Size) that is fit 100% to a Empty Max Tube ( where currently the 2x4 Blocks are set)
Mostly a 4 Diggit Block of a other manifactur still not fit on those tubes cause every companay got a other Pin logic or setup !

Whatever this is finaly not needed cause we not want the "controller" directly behind the Display. Normaly we want it near the Mega ( somewhere in the back of the Panel)

So i agree to Stephan. The cheapest and easyest way is to buy MaxTubes (no matter witch color of LED) BUT with a GREEN PCB. This one are the "removeable diggit" ones.
If you pull them Up you can "wire" your 3 Diggit Display. Sure its not perfect as a PCB.... But if you not have experience and the needed tools to build a PCB in perfect quality then this process take you more time, money and misstakes as to wire the display handly.


About your question.

I Recommend to work with 14 Diggits instead of 15 ( as you said) . It is not possible to split a "Block" over more then one Chip.
If i check the Electrical Display in the web (Link i post above from Youtube) then you need 4x 3 Diggits and 1x 2 Diggits.
A Max got 8 possible Diggits. If you plan now with 15 Diggits ( 5x3) then this is not Possible !!!!!!
One Max can include 2x3 and have 2 pins left .... So you can use 4x3 Diggits with two max chips.... But NOT a 3 Diggit Block now on the remaining 2 Empty Pins on each Max.
For a Solution with 5x3 Blocks you need finaly 3 Max Chips ! ( By the way.... This is finaly much more easy.... I would use 3 Max Chips if that would be my project)

About your line setup with a self build PCB....
Important is.... Every Block (3 Diggit or 2 Diggit) need 8x Segement Line form the Max you will connect it... AND Cathode Lines in number of used Diggits ( Also from the used Max Chip)
If you build for example a 2 Max System .... MaxA have 2x3 and 1x2Block and Max B have 2x3 Block and 2 Diggits empty ... THEN
Segment Lines from Max A must be lined to the 3 Digit blocks ( 2x3 1x2)... They can be splitted. the Cathodes must be lined individualy to each display.... Diggit 1,2 and 3 must be lined to the first 3 Diggit Display....Cathode of Diggit 4,5,6 to the Second .... And Cathode 7,8 to the two Diggit Display Block. Here you can NOT split it and each line must be seperate. ... Same is done with Max 2 .... Segemnt Lines to the remaining 2x3 Blocks ( spliting is possible... Simply go to Display 1 and set Display 2 behind.
The Cathodes go again individual... 1,2,3 to Block 1 4,5,6 to Block 2 7 and 8 stay empty.
NEVER use Segment Lines from Different Max Tubes in one Display or use Segemnt and Cathodes of different Max Chips in the Same Display !


*****
Summary.
If you be able to design and produce high quality PCB and you can solder SMD then you can do that. If you still a beginner its much more easy to use wires here.
[Last edited by pizman82, 2019-02-11 06:50]
Good Luck !
2019-02-11 06:44
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Apeshaft
Posts: 51
Supporter
Hi Stephan and Pizman and all others who are interested,

I here give you version 1 of my Elec panel schematic,
please tell me any improvements or corrections I need to do!

2019-02-11 17:44
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StephanHo
From: EDDG, Germany
Posts: 1150
Supporter
Hi Apeshaft,

I see several mistakes in the structure:

1. the D3 line of D2 comes from IC1 DIG5 (pin 10). Segment F of D2 also leads to this line. Either this is superimposed or it is wrong.
2. This also applies to the management of SEG F (pin 15) of D1.
3. at 1 and 2, the lines must be relocated.
4. Line Dout (pin 24) of IC1 leads to SEG A (pin 15) of D1, also to A of D1 and D2.
5. with the capacitors C2 and C3 the polarity is missing - danger of explosion with wrong connection! C1 is missing?

Recommendation:
The resistors R1 and R2 fit with 9.53 k in no E series. It should be taken 10k resistors. Depending on the brightness of the segments, resistors up to 56k can also be used here (avoidance of glare)
Grüße,
Stephan
2019-02-12 00:21
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Apeshaft
Posts: 51
Supporter
Thank you Stephan,

I will make corrections accordingly.
Can Mobiflight handle this way of serially connecting the drivers or should I change my approach and set up each driver individually? For now I am only using for example 1 DIN input for two drivers. Very unsure of this will work in an Arduino environment.
2019-02-12 00:54
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StephanHo
From: EDDG, Germany
Posts: 1150
Supporter
You are welcome ;)

If you install the 7 segment device, set it to two MAX chips. Then you can address them later in the config individually (both the chips and the digits).
This fuction is called Daisy Chain. So you can cascade up to 8 MAX chips (64 digits) to one chain and you'll need only three pins of your MEGA.
Use the search function in this forum and look for MAX7219 and you will find a lot of applications.

Use the 7 segment tutorial from above.
Grüße,
Stephan
2019-02-12 01:21
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Apeshaft
Posts: 51
Supporter
Hello again,

So I've rectified the thing you pointed out for me.
Do you think it is ready for transferring to PCB?

2019-02-16 22:01
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StephanHo
From: EDDG, Germany
Posts: 1150
Supporter
Hi Oskar,

it seems to be ok :)
Grüße,
Stephan
2019-02-16 23:55
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