MobiFlight Community Support

First of all congratulations on a great bit of software.

I have recently started experimenting with Mobiflight trying to get to grips with connecting various devices and interfacing to FS2020. So far so good but now I am looking at using a 7 segment display with max7219. I connected it OK and configured it to display the COM1 standby frequency.

When I first start a session it works OK and I am able to change the frequency with an attached rotary and see this reflected in both the sim and the 7 segment display, but intermittently the 7 segment will act in different ways. Sometimes it just shows random characters in random positions, sometimes just one half of the frequency, e.g. kHz, sometimes off altogether.

Initially i thought it was a poor connection somewhere but then I found that every time it happened the solution was to upload the configuration from the modules dialog. All the other devices continue to work fine when this happens, (LED, switch and rotary encoder).

Any ideas anyone?

Initially i thought it was a poor connection somewhere but then I found that every time.....

Thats it !

The Max7219 Chips get initiallised on Startup of the Arduino Board. ( So when you power your PC /Connect the USB of the Mega) but also when you Upload a new config ( what result in a restart of the arduino by itself).

Your Problem:
In case of a bad connection the Chips get struggle.... The only way to "reset" them is to start the Arduino for new.
So you not have to recreate the device within the modules tab.... Also a press on the Reset Button on the Mega or a Disconnect of USB Wire for a second do the same.

Solution:
Max chips must be wired 100% perfect. All connections must be solder. So a Breadboard testing will not work and also no loose Dupont wires.
Just a touch of the table ( or the vibration of the Encoder when you turn in a new frequency) can be enough to struggle the Max if there is a loose connection or a just 98% perfect Solder Point.

*********
So... Doublecheck every wire and do it best you can.
If it is connected perfect those issues no longer happen.
Most easy way is to work with PCB here instead of handwire the Max Stuff.


EDIT:

On other hand your reported problems can also be power related.
If your Power is not stable ( e.g. lots of LED or a Motor on the Arduino) can occure in issues.
Also Chaining MAx Chips must be done with a parallel 5V line.

So just to say this.... Power is a factor too.