MobiFlight Community Support

Hi all,

Anyone got Mobiflight loses connection to the Arduino Mega randomly?
I am using 3 Mega for my Airbus FCU without external 5v Power, just using USB power only. There are plenty of 7Segment & Led & Encoder.
It works fine. However sometimes, the 7 Segment loses some segment, sometime all segment turn off, encoders and Led still working fine. It looks like an usb ports loses power randomly. (I have already disabled USB power saving in Window device manager).

Restart Mobiflight, and the firmware of those Mega could not be uploaded again.
Restart PC and mobiflight, all Mega back to work fine, without firmware re-uploading.

I think the problem come from the board which use 5v pins. Because I got other 2 Mega for Airbus MCDU (Button only, no Encorder/7 segment) and those boards always work fine even through USB Hub (no external power).

So my question is that required to plug external power for every Arduino Mega to avoid the power bouncing?

Thanks

How many 7-segment LED's do you have? I have a COM/NAV setup with 8 of the 8-digit MAX7219 LED modules on one Arduino Mega.

If you chain multiple modules together, the modules will lose voltage...the first module will get the 5v, then the second one will get and so-on until the last module.

You can connect the VCC of your modules directly to the 5v output of the Mega (use a breadboard or some other way). I decided to take out the diode on each LED module and solder a bridge rather than wire each module to the 5v supply of the Arduino.

I don't know if this is your issue or not. Maybe provide more details on your setup (type of LED segments, how many of them, etc)?

I have a powered USB hub for my Arduino/Joystick setup but the Arduino cards are not connected to a separate power supply here.

Mike

...also, if you are getting random characters or missing characters on your LED module(s), make sure the wiring is correct and that MobiFlight is configured correctly with the pin assignments.

Mike

Hey Guys !

Basicly at the moment we observe some issues in 7.4 ..... But THIS looks for me as a Power Problem ! ( Or does the same Setup still work fine in 7.3.2 ??)

Note:
If Problem is only in 7 Segement Parts please do the check, mikeb has recommend.
If you Chain the Standard Ebay Modules there is a diode set, that reduce power level on EVERY Module by 0,7v That means 1. Module get ~4.3v second get ~3.6v
At 3. Module and all follows the powerlevel is to low ! That occures in errors, missing diggits and so on.
Please get shure you wire the 5v NOT from tube to tube.... Use 5v direct from board to every Module ! ( or remove the diodes if you have good solder skills)

Additional you have to check the Power Limits of the Board and of your PC. Not overdrive the Board and the single Pins. Please stay always within the limits !

Finaly.... I not have a complex cockpit till now but i read a lot about this.... I think it is not needed to power up every single Board itself.... A Maby good solution is to use USB Hubs with a external Power device..... Like this https://www.amazon.com/Adapter-Transfer-laptop-Ultrabook-leedemore/dp/B01EKU1XKG
if i understand right then this Hub not have to use the Power of the PC.... It supports 2A Power ( What means 4x500 mA )
If you setup your devices that no Board needs more then 500mA then everything should be fine !

Thats why i recommend in some postings to split up the devices..... If you for example need 3 Arduinos in a project then NOT use 1 Board only for LED One Board Only for 7Segment and Motors and 1 Board for Switches...... Try to split up the Outputs (That need Power) over all used Boards.... If Possible uniformly. !

Thanks guys.

I have 3 arduino Mega for a FCU.
1st Mega for 2 - 7Segment modules in chain.
2nd Mega for 3 - 7 Segment modules in chain
3 rd Mega for Led only.

I just found that my mistake in chain 5v pin instead of plug VCC of each module to 5v into the Mega.
I will try again to separate VCC Pins for all the 7Seg module and report later.

But surprisingly that this power problem happened randomly, not all the time.

Another issue that I have figure out that all my 3 Mega using extended usb cable to plug in to PC. That may caused the power shortage ?

Will report back

I believe the VCC in chain is the problem.
I separate VCC of each 7 segment module to different 5v pin on the board and the problem went away.
Thanks guys.

Hi all ,

Is it possible to use an external 5v power source with Arduino to power 28BYJ-48's steppers & stuff.
I am just thinking it may help save arduino 5 volt to power led's and stuff.

regards
nathan

Hi Nathan,

I strongly recommend that the stepper motors with a separate power supply to feed.
As long as the stepper has not yet run, it does not need any power, but once it has run, each stepper needs about 210 mA of power in idle! With two stepper motors, the mega has already reached its limit of 500 mA.

Therefore always a separate power supply. Plus and minus to the stepper and the minus (GND) of the power supply in addition to the GND of the MEGA. In no case connect the + 5V from the external power supply to the 5V of the MEGA!

So you're just right with your assumption to use an external power supply for stepper motors.

Hey Stephan,

Great Information mate !!
well i thought i would ask before i install them into my 737 sim pit ,i am using one for my flaps gauge and one for my yaw gauge.
USB can only power so much lol.
thanks and i greatly appreciate your help and the mobiflight team for this awesome piece of software

Kind Regards
Nathan