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Posts: 35

I have built my full size flight simulator in my house for a Boeing 737.
It is working great and have many mobiflight units together with many Arduino 2560 Mega.

However now I want to add another arduino 2560 mega and wonder hos to connect it so it will be correct at once.

My simulator has, obviously, its own computer and I develop my panels on another computer now.
Is it possible to use a standalone computer to program the new arduino mega card before I connect it to the simulator (P3D v4 with PMDG software) or is it better to connect the new arduino directly to the flight simulator computer without program it on another computer?

What I would like to know is if the other already installed arduinos will be affected by a new arduino that might make the not work so good together.

I use one arduino for the MCP, one for front panel lights, three for overhead panel, one for thrust, flaps, spolier and another three for communication panel.

The new I want to add is for some more LED's on the overhead panel and for the IRS display and flaps indicator on the aft overhead display.

No problems for me t connect it directly to the flight simulator computer but a benefit if it is possible to do all the programming on my standalone computer before connecting the panels to the simulator.

Hope someone can give me suggestions on how to best add a new arduino mega 2560 to an already advanced system.

Happy flying
2020-01-16 14:22
From: ETSI, Germany
Posts: 3862
Technical both is posible.....

If you just like to set th devices ( hardware settings where you create for example a LED on Pin x and a button on pin y) can be done "everywere" .
For this Upload technical the arduino can be empty, too. Mobiflight not care about if there is realy a LED in the Pin or not.

If we talk about creating the software config it is also possible to do this on a external PC.... Whatever you need the original *.mcc file from your main Project..... Cause you like to "add" the new data to the existing file. Creating a new file and "Copy" it INTO the other is basicly possible by edeting the file with a programm like notepad++ but not recommend.
Whatever..... If you do this on external Computer most of Configs won´t work and are problematic cause the needed devices are not Set ( The old Arduinos on other PC).... So its more comfortable to make the Software Configs directly on the FlightSim Computer!

To prevent you from lots of work..... Its high recommend to make Backups.
Save your MCC File before you add the new things..... Also not delete older backups.... Create everytime a new one and hold the other. If there is a problem you can simply "downgrade" multiple steps.
Same for MFMC Files..... If your System is working fine then save the Board settings from Each MEGA to a file.... And backup them.

Summary.... I would set the devices whatever on Computer A or B ..... But i would write the new configs on Main Computer finaly.
Good Luck !
2020-01-16 17:51
Posts: 35
Thank you for your reply.
Sounds better to connect it directly to the "flight computer" then.

What I want to use the new arduino for is the IRS output, only to my 7 segment displays. And later on connect further LED's to it.

Had som problem, or rathar I have problems when connecting too many 7 segment displays to one 2560 Mega. That is why I was asking.
Guess that One aduino mega 2560 cannot send data to more than 4 7 segment displays (7219).

Once I tried to connect COM1 active + standby (2 set of displays in total) + transponder (one 7219) + ADF, that did not work very well. Still having problems with the ADF, it will never light up whatever I do, but that is a later problem.

Now it is only for my IRS output so I can read the position on the display on the overhead panel.
2020-01-17 18:19
From: EDDG, Germany
Posts: 1573
Hi sebpil,

it should not be a problem if you connect more than to or three MAX7219 with their 8 digits each.
I myself use two chains with at least 14 MAX7219 boards on one Mega.
1st chain is COM1 act/sby, COM2 act/sby, NAV1 act/sby, NAV2 act/sby and the 2nd chain is DME1, DME2, ADF, trimvalue and XPDR.
With this combination I do not have any problems.

But I modified the boards. I replace the diode D1 with a wire bridge and replace the 10k resistance with one with 48kohms.

Do you have your boards in that way, that every board has directly 5V or did you chain the 5V from board to board without replacing the D1?
2020-01-17 23:07
From: ETSI, Germany
Posts: 3862
Just to give the Official Numbers.....

A Max7219 Chip is able to Light 8 Diggits
Mobiflight allow "Chains" with a maximum length of 8 Chips ..... So a Single Device can include up to 8 Chips and 8x8= 64 Digits
Mobilfight allow FOUR Max Devices on a Mega .... So Technical you can use 4x8 = 32 Chips 32x8 = 256 Diggits per Board.
Mobiflight not limmited the Number of Megas ( Just by Windows ComPort and USB Limits... Maby nearly 128 Boards)
So you can handle much more Displays and Max Chips if you use multiple Megas.


Your Problem is the Power Managment. If you build Chains you must wire 5V single to each Tube ( NOT by Chain it from Output Tube 1 to Input Tube 2)
The 3 Data Lines MUST be looped ..... The GRD Can be looped, too without Problems.
Alternate is to remove the Diode Stephan told you..... Then also the 5V can be chained from tube to tube.

Personal Recomendation....
I think conservative..... If you still use more Megas i would not make Chains ( or to long chains) . System is more tidy and logical if every device got own Name and adress.
So its no problem to use 4x8 Displays on a board.... But i think use 32x1 Display on 8 Different Boards looks more tidy and easy. Result should be the same !
Good Luck !
2020-01-18 15:54