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MAGICGURU
Posts: 47
Good evening I would like information on a problem I have on my overhead built by me.
Inside my overhead I have 6 Arduino Mega powered by the USB hub of my PC.
the problem is that when I use the encoders for FLT ALT and LAND ALT the displays of this function either turn off or show random digits.
I state that I have already modified the MAX 7219 by removing the diode d1 to make it work at precise 5v.
also I tell you that the displays the servos work with a separate 5 v power supply I don't know how to solve the problem.
Help me please

Best regards

Stefano
2020-04-03 23:06
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StephanHo
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From: EDDG, Germany
Posts: 1525
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Hi Stefano,

you should check the wiring to the MAX-modules. The MAX is extremly sensitive about his wiring. Have a special attention on the GND-wiring.
If only these two displays show weird numbers everything speaks for a wiring problem. What happens when you press the test button? Are all digits ok then?
Grüße,
Stephan
2020-04-03 23:35
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pizman82
Moderator
From: ETSI, Germany
Posts: 3527
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iconMAGICGURU:


I state that I have already modified the MAX 7219 by removing the diode d1 to make it work at precise 5v.
also I tell you that the displays the servos work with a separate 5 v power supply



Hi Stefano.

Please Confirm the GRD of that external Power device that powerd the Max is connected to the GRD of the Arduino where you set the Display Lines ( CS, CLS, DIN)
If not this can occure in massive Problems.

If that is not the Problem .....
Maby try to show for testing a other Value like COM1 on that Displays and change THIS Value also to get a simmular situation

At first we must find out if this is a Hardware Problem ( also electical maby) OR a Software Problem !
Good Luck !
2020-04-03 23:42
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MAGICGURU
Posts: 47
Good evening everyone thanks for the answer, I checked what you suggested but the displays with the max 7219 are connected correctly the ground is connected al pin near pin 52 e the positive wiring is connected near pin 22.
I can tell you that if I use the knob on the overhead of the 737 the displays do not crash and work perfectly, while when I act on the encoders of the Arduino they sometimes work but most of the time they either turn off or show all 8.
When i test the display with mobiflight there are all digit ok!!

Help!!

Best regards

Stefano
2020-04-04 23:08
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StephanHo
Moderator
From: EDDG, Germany
Posts: 1525
Supporter
Hi Stefano,

if the displays turn off or shows 8.8.8.8.8.8.8.8. hen you have a wiring problem. One ore more of your connections are not ok.
Check at first that +5V are on every board, then check the GND. The GND has to be connected to the GND of the Mega. If you use an external power supply connect the GND of the power supply to the GND of the Mega too.
The check the wiring of the data-wires. They should be soldered or have a stable connection on both sides.
Check the USB-connection of the Mega board(s).
Then check the wiring of the encoders. One contact of every encoder has to be connected to GND not to +5V. Do not use external pull-up-resistors.
when you've checked all of that, put one of the displays that didn't work in test mode. Now wiggle the whole unit, which carries the encoders and the displays. If the test display goes out again, there is still a wiring error, a loose connection, a dirty connection. Find and fix.
Then leave the test mode and turn the encoder. what is happening?
Grüße,
Stephan
2020-04-05 00:31
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pizman82
Moderator
From: ETSI, Germany
Posts: 3527
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iconMAGICGURU:

the ground is connected al pin near pin 52 e the positive wiring is connected near pin 22.



I Wondering..... In initial Poting you said ....
iconMAGICGURU:

I tell you that the displays the servos work with a separate 5 v power supply



Whatever.... As we said above... If you use a External Power Suply "somewhere" in your system then get sure the GRD of that device is connected to a GRD Pin on the Mega..... And also that all Mega Grounds are connected together.... Then you can get sure there is no GRD Potential Problem in the future.

******
iconMAGICGURU:

if I use the knob on the overhead of the 737 the displays do not crash and work perfectly, while when I act on the encoders of the Arduino they sometimes work but most of the time they either turn off or show all 8.



As Stephan said this is pretty sure a wire Problem.... As we said in the past.... Max7219 Tubes are verry sensitiv. If problem occure after you touch a element ( Encoder) that is nearby the Display then pretty sure the moving of that Encoder is the Problem. Maby in rare situations there is a electrical problem betweeen the Encoder Wires and the Display lines so Encoder turning electrical impact on Display Data lines.... But i don´t think so.


Summary: I agree with Stephan. Rework your connections of that Displays.... Then all is fine !
Good Luck !
2020-04-05 09:47
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MAGICGURU
Posts: 47
Good evening I update you on the display problem, the problem has been solved as I had used 5-pin encore connecting them all.
I unsoldered the encoder and used 3 pins.
I connected 2 pins on the Arduino and the central pin to the GND.
Thank you very much for your support.
Best regards
Stefano
2020-04-05 18:31
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