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auransbey
From: ROME, Italy
Posts: 59
Good morning,
I'm completing an MCP737.
I would like to know if I can connect the 6 displays (max 7219) with a single MEGA 2560.
I seem to have understood that a mega card can only withstand 1 display.
Thanks as always
MF - simply wonderful !!
2019-03-06 11:02
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pizman82
Moderator
From: ETSI, Germany
Posts: 3322
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Hi

This is all already written in the FAQ .... Please check it next time ! https://www.mobiflight.com/en/documentation/faq.html

To awnser this in short words.....
One MEGA can handele 4 Max Chains.... A Max Chain can include 1-8 Max Chips .... And Finaly a Max Chip can include up to 8 Diggits.
So you can theoretical handle 256 single Diggits with only one MEGA.

Note:
If you build a chain get sure you use 5v directly to each tube ( not chain it).... OR remove the resistor by youreself.... Else a Chain will not work !

Basicly i recommend always to split your devices.
If you alredy work with 2 Megas ( maby you still plan for the EFIS) then split the Displays and LED over multiple Arduinos....
For example 2 Displays on Mega A 2 Displays on Mega B

Also i recommend to split your Displays over multiple lines. So if you have for example 12 Pins free then set your 4 Displays "each single" to the Mega.
If you have 6 Pins left then split it into 2 chains with 2 displays each.
Only if you have just 3 Pins left.... then make a 4x Chain. ( It will work but its more comfortable and usable to split it)
Good Luck !
2019-03-06 11:41
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auransbey
From: ROME, Italy
Posts: 59
Thank you very much, I had not thought of FAQ !!
but I can not understand well what is meant by chain !!
Can you explain me well?
Many thanks
MF - simply wonderful !!
2019-03-06 12:38
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pizman82
Moderator
From: ETSI, Germany
Posts: 3322
Supporter
Yes.

We Use normaly MaxTubes ( like this.... https://www.amazon.de/8-Digit-Display-MAX7219-Digital-Control/dp/B00P9277BE
Whatever you also can use the raw chip an wire the stuff yourself.

Important for us is the wire and pin logic.

A Max must be set to the Arduino with 5 Lines... Din, CS , CLK, 5V and GRD .
You create this as Device in the Settings Tab of Mobiflight ( For example on Pin 10 Din,11 CLK ,12 CS)
Then you have ONE Tube on that Device and you can use it.
As i said.... This can be done 4 time per Board .... So you can basicly set 4 Tubes via 12 Pins .

Now about the Chain

The Max Chip allow is to build a chain.... That mean the MaxChip have additional to the 5 Input Lines also 5 Output lines ( On Tubes Left is INPUT Right is Output)
They are named identical.... Only DIn is named Dout on the right side.

If you need TWO Displays for example you can wire the second behind the first.... So CS Output of Tube 1 is wired to CS Input of Tube 2 .... Same with other lines.
NOTE: As i said above... 5V got also a Output but it will not work without remove the resistor..... So its better to wire 5V directly from Arduino to Tube 1 and Tube 2 .
Those Chains can include up to 8 Tubes. ( With 4 possible Chains... each up to 8 Tubes you can set theoretical 64 tubes with 8 Diggit each... result in 256 Diggits)

The Only setting must done in Mobiflight is the NUM field.... When you create a Device there is standard "1". If you use more the one Tube on the 3 Pins (Chain) you must change this value to the number of Tubes you like to use in a row. NUM1 = One Tube NUM 2 = Two Tubes Chained.... and so on until 8 max.

I hope that awnser your question !
Good Luck !
2019-03-06 13:28
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auransbey
From: ROME, Italy
Posts: 59
yes, now everything is very clear !!
I thank you very much for being always available
MF - simply wonderful !!
2019-03-06 14:31
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StephanHo
From: EDDG, Germany
Posts: 1488
Supporter
Here you can see how to built a chain:

https://www.mobiflight.com/forum/message/4634.html
Grüße,
Stephan
2019-03-06 16:33
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auransbey
From: ROME, Italy
Posts: 59
Thank you very much, Stephan and Pizman!
today I solved the DISPLAY problems.
now I find a problem with ENCODER for COURSE control on the MCP 737.
the EVENTID PMDG is 70008 but I can only rotate by increasing the degrees.
I can not understand if I have to use special parameters.
Thanks again for the fantastic mobiflight software!
MF - simply wonderful !!
2019-03-06 18:58
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StephanHo
From: EDDG, Germany
Posts: 1488
Supporter
Hi auransbey,

look at the end of the PMDG-EventID-List. There are the special parameters to use mouse events.

For the EventID 70008 use in the ON LEFT tab as param 8192 and in the ON RIGHT tab the param 16384. That are the parameter for mouse-wheel down/up.
Grüße,
Stephan
2019-03-06 19:36
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auransbey
From: ROME, Italy
Posts: 59
Fantastico, come sempre molte grazie !!
MF - simply wonderful !!
2019-03-06 20:14
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auransbey
From: ROME, Italy
Posts: 59
Fantastic, as always, many thanks !!
MF - simply wonderful !!
2019-03-06 20:14
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auransbey
From: ROME, Italy
Posts: 59
thanks for your explanations
they are always very precise.
unfortunately I have been experiencing problems for some days that I cannot solve.
if I connect 2 or 3 7-segment displays - 8 digits to a single mega card strange displays occur on the displays (for example all the figures on and fixed or other oddities)
1) the contacts on the displays are welded.
2) the displays are with Max 7219
3) the displays are slightly larger than those of a MCP 737
4) the displays are powered by GND and 5V of the mega board.
5) in 1 case the computer emitted 2 sounds as if a USB were
     disconnected and then reconnected.
I am doing a lot of tests but I can't solve the problem.
Is it necessary to connect the displays to some specific PINs (analog or digital)?
if further explanations are needed I can provide them.
Many thanks
MF - simply wonderful !!
2019-03-19 15:43
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auransbey
From: ROME, Italy
Posts: 59
I can make other clarifications:
1) power is removed from the MEGA each time the system is started.
2) LEFT COURSE DISPLAY - PIN 29DIN, 30CLK, 31CS
3) RIGHT COURSE DISPLAY - PIN 32DIN, 33CLK, 34CS
4) DISPLAY HDG - PIN 38DIN, 39CLK, 40CS
5) GND DISPLAY AT GND MEGA
6) VCC DISPLAY AT 5V MEGA
all settings (number of digits, padding, display number) seem to be correct)
7) if I insert in the connection only the HDG display it seems to work a few times

Thank you so much again
MF - simply wonderful !!
2019-03-19 16:13
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pizman82
Moderator
From: ETSI, Germany
Posts: 3322
Supporter
Old Problem... Maby a forum Search also give you good hits.

Multiple Reasons.

At first you must know... Do you set every Display as a single Device OR do you "Chain" your Displays.... So you have only 3 Pins + 5v and GRD from Tube 1 on the Mega.... and all other Tubes are wired in chain... So Tube 2 ist wired to tube 1 and so on ??

In case of a diode on the MaxTubes you can not wire more then 2-3 Tubes in a row cause you have a Power problem.
Solution is....
Remove that diode
OR
Wire Each Tube DIRECT to the 5v Power of the Arduino Mega. ( Then GRD and the 3 Data Lines are wired from tube to tube BUT 5v is wired direct to Mega for each Display)

****
If Problem already occure when you use the tubes in a single setup ( Or by do the Power workflow above in a chain) THEN Your Tubes are not corrct solder.
Lots of Chineese Tubes are already broke wehn you buy them ( bad solder work)
In That case you must resolder the Pinheaders or you try another tube and put the broke one in the trash !
Good Luck !
2019-03-19 16:13
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auransbey
From: ROME, Italy
Posts: 59
Thanks for the reply.
the displays are connected individually.
each of them is connected to 5V and MEGA GND.
MF - simply wonderful !!
2019-03-19 16:16
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pizman82
Moderator
From: ETSI, Germany
Posts: 3322
Supporter
Then you must check the solderwork from the INPUT and OUTPUT Sides.

Input Side is Easy.... Simply connect your Display each as a single device. If they work in single usage then the LEFT pins are All right

to test the Right pins you build a 2 Display Chain.
If the SECOND Display workes fine then the Right Output Side of the FISRT Display is all right. If it not work ( And you already check it bofore in the single setup) then you know 100% that the issue is in the First Displays Output Pins.

Another spot of Problems can be the Display Pins itself ( where the 2x4 Blocks are mounted )
Move the problematic Displays a bit by hand Press them from above with your fingers.... Does some segments "blink". If yes thn the solder of the Displays is broke.
(Mostly that happen with the fixed Displays.... The Removeable ones are normaly better here)
Good Luck !
2019-03-19 16:31
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