MobiFlight Community Support

Hallo,

For a few days i'm playing around with mobyflight now, great software .

I've a question about the 7-segment modules, i'm not able to get them working in series.(daisychain)

every module has its own power, during setup i,m using the numbers 1 to 4 ( each module 1 number).

Please advise

Vespucci

Ciao Vespucci,

you wrote that every module has its own power supply... have you already tested your modules seperately?
And are they working when you run them parallel?

Regards,
Chris

Hai Bonanza,

Thanks for your answer. In parallel there working fine.

I'm using the exact same modules as discribed in the tutorial.

I now there is a topic about this issue in German and understand only 50% whats written there.

Cheers
Alex

What do you want to know exactly from the German thread? It would be a pleasure for me to translate the posts for you

One thing I've found in the German section (with translation):

So ich habs! Vier Module in reihe funktionieren
Finally I got it! Four daisy-chained modules are running

Es Liegt einfach nur an der Spannungsversorgung der Module!
It depends simply on the power supply of the modules!

Wenn man die Spannungsversorgung in reihe betreibt kommt ab den zweiten Modul einfach zu wenig an,entweder jedes parallel oder jedes zweite.(Nur 5V und Masse ist gemeint die Daten pins weiterhin in reihe betreiben!)
When you configure the power supplying in a daisy-chained way up there's simply too low power from the second module on... (I only mean 5V and GND, the data pins still can be run in serial configuration!)

...

VG Chris

I have similar problem. Each time i attach the 4th module the 4th module is not working. I have used the suggestion given above and have pulled a separate 5V supply and ground connection from the arduino to the 4th module, but when i test the connections in a Test mode, i get random numbers displayed on the 4th module. I'm not sure why. Any solutions, i would appreciate it greatly.

Hi Binki,

connect every board with 5V separately.
You can also wire bridge the protection Diode D1 on every board. Then you need not connect every board with 5V, then cou can wire the 5V from board to board - but only then!!

Please note: if you connect the first board with 5V it will only run with 4,3V due to D1, the second board will run with 3,6V because there is also a D1. Already the 3rd board runs with only 2,9V but the lower limit for the MAX7219 is 3,4V. This is typical, as a silicon diode always drops approx. 0.7V. You see, already the 3rd module can have considerable problems with the processing of the data, also the following modules.

Pleas try one of this solutions an report the result here. Thanks!

EDIT Pizman..... Stephan es geht wieder los mit den Doppelpostings Sorry !

EDIT2 Stephan: doppelt hält besser

Hi Binki.

In That Case it´s ok.... But please not refresh verry Old Topics in the future !

About the Problem.

On Max7219 problems with Daisy Chained systems we know two Issues.....

1. Broke Solder Points in the In or Output Pins Headers
In this cheap Chineese Products sometimes the Pin Rows on the Left (Input) and/or on the Right (Output) are Broke.... They looks ok but the solder isn´t 100% perfect and so it not workes.

There is a recommend Testing Procedure for that ! ( Note i recommend to get shure you have 100% good Connectors.... A Breadboard setup is mostly not working. Get shure the connection on Max tubes are soldered or with connectors.... Not simply put a wire in the empty holes.... That mostly give problems)

A) Input Side....
Create on a Arduino a Output Device for ONE Max7219 ( No Cascade)
Create a Config to test this with THAT Device. A Offset is not specific... You will only use TEST Function.
Wire ONE Max7219 to the used 3 Pins and 5v and GRD on that Arduino.
Start Mobiflight and use TEST Button in the Config of the Output..... If Display got a working INPUT side it should show 12345678
NOW... Close Mobiflight, Remove the Max7219 Display and set the next Display you want to test instead of the first one....
Do the Same again.... Start Mobiflight... Run Testing Mode in the Config itself and check if it show 12345678.
Do this with all Displays you like to use in your Projekt.... Now you Know.... The INPUT Side (Left 5 Pins) are working fine.

B ) Output Side ....
Now Create a Device on the Arduino with a TWO Display Setup.... Use NUM=2 for a 2 Display Daisy chain row.
Create a Output-Config that use as Device the SECOND Display in the Row.... Like in Testing A offset is not important... We will use TEST again.
Now please wire a 2 Display Chain to the Pins.... The Second Display is wired from the Output Pins ( Right side) of the first Display.
Use TEST Function again like before.
NOW the effect.... We already know from Test A that Input sides of both displays are working ok..... If You see 12345678 THEN we can confirm that the OUTPUT Pins of Display ONE in the row are ok, too.
If NOT.... Then the Output Side of the FIRST Display in the Row are Broke!
To test the OTHER Displays you got you have to close Mobiflight and remove the FIRST Display in the Chain with a other one....
If you do that with all Displays you can Confirm... The OUTPUT Pins on Right on the tested Displays side are working fine, too !

If there is a Problem you have to resolder the Pins youreself or you throw the Tube in the Trash and take another one !

***

2. A Electrical Problem with daisy chain.

We talk about this multiple time..... The Max7219 Tubes got a resistor that reduce Power Level by maby ~0,7v.
If you use in the chain the 5V always from the Tube behind then the first Tube got 4,3v the second got 3,6v the third got maby 2,9v and so on.
That occures that 3. or 4. Display have not enough power to work.

To solve this you can remove the Resistor yourself from the Boards ( High solder skills are required) OR you simply support 5v direct to each tube.
You can wire the 4 Lines ( 3 Data Lines and GRD) from tube to tube.... BUT you Use for 5v each a direct wire from the 5v Pin of the Arduino !
So you make a "bypass" from the resistor.

********
i Hope that awnser all questions !

Small Correction:

Do not remove the resistor (R1), only the diode (D1) - wire bridge !

Thank you very much it worked

Removed and bridged D1 on 7 segment circuit board and everything worked perfect with 5 series displays. Thanks for the advice!