MobiFlight Community Support

good evening dear friends,
as always I ask for your help with my realization of cockpit 737.
I am proceeding with my project and, at the moment, I use 5 mega cards.
https://youtu.be/99xv0NwUezM.
I am currently doing test cycles lasting 7 hours during which I check the operation before proceeding further.
mega cards are NOT powered externally but receive power from the PC.
I purchased a 9 Vdc - 12A power supply for mega card power supply but I have not implemented yet.
during the test sessions it happened that 1 or more mega cards were suddenly not recognized by MF.
It is necessary in these cases to stop the execution of the program (MF) and disconnect and reconnect the USB cables.
After MF restarts everything works ok.
This problem occurred twice in 6 hours of testing.
I think:
- excessive USB current load;
- not perfect USB cables (I use German HANA cables);
- use of USB 7 ports HUB (also HUB is of good quality);
I would be very grateful for your opinion.

thank you very much

Here Stephan is your man i think.

I personaly have no experience with a high number of arduinos.... But the basic system most people use ( as i know) is the "Power Hub" Logic,

A high number of Boards ( maby with standard Hubs on one USB Port) can be problematic with the "500mA" Power supported by the USB Port.
So most users work with "powered Hubs" .... So for example a "4 Port USB Hub" with a 2000mA Power suply .... So Every USB Device got 500mA directly from the HUB and not need the PC Internal Power.

*****
About the Cables...... Here i also heard about problems if you use cheap and long cables..... But i can not confirm that. For testing i use 3 Boards.... 1 Hub (Powered) and Summary 4 USB Cables ( 1x PC-HUB 3x HUB-MEGA ) All 4 Cables are different manifactures ( Cheap delivered with stuff like TV, DiggiCam and HP-Printer) I Have no Problems.

Thanks Pizman for your reply.
unfortunately I think I'm in trouble.
maybe, as you said, Stephan could help me.
For each flight test I get a disconnection of one or more cards.
moving any button or encoder on that card the TX or RX diodes flash regularly but I have no effect on the simulator.
By querying the PC, the corresponding COM ports are functional and do not show any anomalies.
Turning off and restarting MF I get the "orphaned card ...." message.
I have to turn off and restart the PC every time.
thanks for every suggestion.

Hi, I proceeded to externally power all 5 mega cards with a 9 vcc - 5 A power supply.
I have done about 30 hours of flight and I have not found any problem of USB disconnection.
I believe I can say with certainty that it is necessary to externally supply ALL the mega cards.
I communicate the result of this experiment mainly to inform MF users.
as always I thank you all for this wonderful instrument !!
I take this opportunity to inform you that I made UPDATE of version 7.5.3 and performed about 2 hours of testing on lost INPUTs.
before proceeding with the upgrade I had about 10% of input lost in my cockpit and I considered this as an evil that had to be tolerated with patience.
during tests with 7.5.3 I found 0% input lost.
I am very happy and I thank the great "DocMoebiuz" and all of you for your efforts for our well-being.

Hi

Nice to hear the "Lost Input" Problem is also gone for youreself ( and many more users)
After our personal testings and lots of feedback until now i would say, Sebastian realy find the issue now and this 4 Year threatment is finaly solved.

About Power.

Here i think this is not a global Problem..... As you say... If Power is problematic then issues occure. But its hard for me/us to define a limitation here in case we not see the systems from all users. We can just inform about the limits like 500mA by board.
In case we not know how "strong" the internal Power suply from a Computer is ( Mine got for example 1000 Watt whatever i would need only 550 for all Hardware in Computer) .
So maby my System can handle much more Megas on USB Power as a other System with a much smaller PSU.

Summary.... I think its no matter what you do.... A Strong PSU, a external Suply or Powerd Hubs..... Important is finaly that every Mega got enough Power to work.

It is important for me to point out that I had done a lot of tests with fed HUBs and I had not obtained good results.
I am convinced that the mega card MUST be powered externally through its connector with a voltage not exceeding 10vcc and at least 500mA available.
any other strategy seems uncertain to me.

OK. Thats a interesting fact.

Maby some professionals can in the future make a electrical check here..... Would be interesting how much power those hubs support.
Maby your right and the Hubs just "tell" us they have 500mA but support much less power as we think.

Thanks for research that !

Dear friends,
I took advantage of my free afternoon to perform some tests on the power absorption of the mega cards.
I hope for a good translation from Italian.
My cockpit uses 5 mega cards for a total of about 87 LEDs, 6 DISPLAYS (mcp) and 2 steppers (28BYJ-5V).
INPUTs are irrelevant to my test.
The total load at rest (LED off, DISPL off, STEPP off) is 410mA.
The total load in service (LED on, DISPL on, STEPP move) is 1,700mA.
This load must be designed with a voltage of 9.9 V and therefore with a total power of 16.9 Watts.
this power with a voltage of 5 V will have a load of 3.400mA.
this means that each mega card will have a load of 680mA.
Considering that my mega cards have a number of LEDs, DISPLAY and STEPPER equal to about 50% of their project possibilities.
for this reasoning it is likely that a single mega card can have a load of 1,000mA.
Such a load does not seem to be provided by a powered HUB.

As always, infinite thanks

Again... Stephan is needed here. My knowledge is not enough to comment this correctly.

Interesting here is maby finaly the "Stepper" Motor. Stephan wrote in the past that those Motors need realy much power.

If you like to make another test you can temporary "remove" the Steppers. If i understand right then a high number of Megas with lots of LED´s and also a couple of 7 Segments can normaly run with simple USB power without problems....
But just 1-2 Steppers can be a real Problem... Maby need more power as the whole other system together. May in that reason Stephan recommend multiple times in the past to power the Stepper external by a Power Unit.

Whatever.... Your Problem is solved.... You recommend a good solution to others..... We can also close that case without further testings ! Your Choice.

Hello auransbey,

that's a thing with the power supply.

Basically, a USB interface can only max. 500mA, even when connected directly to a PC. These 500mA are defined as standard for an USB interface.

In the case of the USB HUBs, a distinction is made between those who have no external power supply as their HUB, that is to say they are supplied via a PC USB interface. Then with a HUB with 4, 5 or 7 USB connections only a total of 500mA can be taken.

For USB HUBs with external power supply usually an external power supply is supplied, which provides 3.5A (even with a 10 HU, because it is assumed that not permanently on each interface 500mA be removed.

As far as the electricity consumers are concerned, you are absolutely right: Inputs do not consume electricity, at least not worth mentioning.
The LEDs will look different again. If you connect 40 LEDs with 20mA each to a MEGA, then the MEGA is busy, because this may consume a maximum of 800mA current. However, since a USB interface delivers a maximum of 500mA, this has the consequence that the additional required but missing 300mA can not be delivered because this does not allow the specification of the interface. So if the power is needed but can not be supplied, the operating voltage will drop. As a result, the MEGA can not work as it should.

A remedy here, provided that the power consumption is caused by LEDs, a higher series resistance for LED, so that e.g. instead of 20mA only 10mA flow. 40 LEDs x 10mA = 400mA. So a halving of electricity consumption. This applies in the case that all LEDs can / should be switched on at the same time. Therefore, when designing the consumer, care should be taken to distribute the electricity consumers so that no overload occurs.

To the stepper motors: These require already as quiescent current 170 - 200mA, in operation correspondingly more
If now 2 stepper are connected to a MEGA, then it should probably collapse in operation, if still a corresponding number of LEDs is operated.

The 7-segment displays are operated in multiplex mode by the MAX7219, whereby only one 7-segment digit is lit per MAX chip. However, since this happens with a frequency of 1000Hz (1000 times on and off per second), this does not notice our eye.

Recommendation: Consumers, such as stepper motors or servo motors, use their own external power supply. The control lines for the motor remain at the MEGA, the GND of the power supply of the stepper also. + 5V come then from the external power supply as power supply for the stepper. Please make sure that the GND of the external power supply is connected to the GND of the MEGA. If a ring lead is used for GND, connect the GND of the external power supply to this GND loop.

You should be careful to distribute many power consumers (like LEDs) to multiple MEGAs and connect large power consumers (like steppers) to external power supply (s). The output voltage of the external power supplies must not be higher than the operating voltage of the MEGAs, ie 5V.

I'm sure if you build your circuits that way, no MEGA crashes and your test runs will be satisfactory.