MobiFlight Community Support

Hello,

First of all, a big thanks to the MobiFlight creators !

I don't know if I'm in the correct section of the forum, if not, I'll let the moderators move this topic

I'm building a home cockpit with a couple of friends, and we'd like to use MobiFlight to display the COM/NAV freqs on a LCD Display, the XPDR Code on a 7 segments display, and the landing gear and flaps positions with LEDs.

So far, we tried connecting one led, the 7 segments display and the LCD display directly to the Arduino, this way it works correctly, after configuring all we need in the software, the devices works as intended.

The thing is that for more convenience (especially to get more 5V and GND pins for the LEDs), we'd like to use a shield board.

When we use one, as soon as we connect the LCD display (it's a 4x20, connected to pins 20 & 21), when we launch MF Connector, the Arduino appears as "Unknown" in the settings, and the devices list is empty (with no possibility to add devices).

This problem only occurs when we connect the LCD Display. Has anyone experienced the same kind of issue with a shield board ? Are there solutions that we could try to make it work ?

Thanks in advance !

Hi

It can happen in rare cases that firmware gets corrupted..... So a little issue ( may in a Hardware Mem chip or so) ..... But this is rare and have no routine....
So if you can reproduce a special workarround for the issue to come again.... then this is not the reason!

Also a wrong Board can be the problem. do you use a MEGA ??? thats the only board that is official confirmed stable. UNO and Micro can work, but we can not garantee.... Specialy if you use more then Buttons and LED ( e.g. motors and LCD) then these Boards can crash. Some people work on that.... And we also plan for a reduced firmware ( without Stepper Motor Support for example) to make them stable.... But this is a future plan.
In Easy words.... Use MEGA.... Then those issues are normaly gone.

Another a Problem can be a electrical issue. E.g. if you have a short cirquit then the Board make a emergency ShoutDown. And this for sure occure in a "unknown Board" .... windows see a Board, but it not awnser in case its crash ( in case of Electrical problems).
May THIS is the problem.... Cause if i understand right, your setup work without the shield, but crash with the shield..... May a single wrong pin thet bridge GRD and 5V.

Also a overdrive of MaxPower ( or a usage of to low input Voltage) can occure in thoses Crashes.
Confirm your devices not use more then 500mA all together AND confirm your Power Suply (USB ) support enough Power (500mA) ..... We also recommend to NOT use a external Power for the Mega.... Only for Devices like the LCD ..... But then combine GRD of external device with a GRD Pin on the Mega !

At last....

Hello,

The thing is that for more convenience (especially to get more 5V and GND pins for the LEDs), we'd like to use a shield board.

You just need one single 5V Pin and one Single GRD Pin for your whole project !
A LED have no 5V ..... It is powerd via the PIN you connect it ( e.g. Pin 10 if you set it as LED Output) .
7Seg can share the same 5V Pin as the LCD ..... The 5V Pins on the mega are technical also combined on the Mega PCB.
Same for GRD..... In Theory you can wire a full Cockpit that use 30 Megas and thousends of devices with one single GRD Pin.
We call this "shared GRD" ..... You have e.g. 10 LED..... Simply wire one single line from a GRD Pin to the GRD from the first LED..... Then from there to the GRD from the second LED and so on..... You can alos use the same GRD and combine it with the 7Seg.

So... Shields are a cool thing.... Specialy to use screw ports or IDC connectors..... But in your case.... The 5V and GRD are no fact. Simply wire them together to one single line each !

Hi!

Thanks for your reply!

I forgot to say that I'm not the hardware specialist in this project, I'm more of a software guy

I can tell you that we use an Arduino MEGA as required but I don't think that the overdrive may be the cause of our problem since we don't have this issue when we don't use the shield. I recall that we used one shield board but we didn't try another one to see if there might be a short circuit with this one. The problem only occurs when the LCD display is plugged (we tried with another identical LCD display but encountered the problem twice).

I'll transfer your answer to my friend who's in charge of all the hardware to see if he can work something out. Worst case, we'll plug everything directly to the MEGA.

On a different note (completely off-topic), do you know if MobiFlight will support multiplexing someday ? I'm asking this, because I joined this cockpit project along the way and most of the wiring was already done using multiplexers and the software side was managed with SimVim which has problems for the displays since the latest X-Plane update. I came across MobiFlight when we were searching for an alternative, and I quickly appreciated the ease of use of MF. I must admit I was a bit saddened to not be able to migrate all the I/O on it (because we'd have to redone all the wiring and there's no way we're doing this)

Basic idea is always the same.....
You already know where the problem is..... Your Setup work without the shield..... But not work with the shield.
So we can still say.... this "shield" make something wrong..... It not must be a issue.... may the design from that shield is pretty different to the way Mobiflght use the Mega.

We have no experience here.... Cause we ( and most users) not use these shields ( mostly build for other things like FlightSim) ..... So only famous shield that is used by MF users is this.....
So no shield with a lot of internal stuff..... Just a plate that move the single pins to screw Connectors ! ..... means no hidden bridged or combined lines anyway.

Finally most users work also with shields.... But not "standard stuff"..... these users simply design a own custom shield as a PCB and let it manifactur in China.

So... Solution: Find out how the shield work.... And what is the Problem..... It can be not on MF side. It must be a electrical fact on that shield you struggle!




***********

About Multiplexer.....
In the past we say NO ( Was against our main logic.... "You need more Pins.... Connect another Mega" )
BUT
IN case hundrets of SimVim Users swap to Mobiflight in case of FS2020 Compatibility..... We get this on the screen. We like to allow SimVim Users to "migrate" in a good and easy way..... So NO. We will not use a Master/Slave System like SimVim.... but we looking forward to support the same Multiplexer that was also compatible in SimVim !

I recommend.... NOT rework all your stuff.... Wait some weeks. Hopefully this comes fast!

Thanks for your reply !

My friend who's in charge of the hardware said he will try something else with the shield but splitting the power supply for the LCD Display

Concerning the multiplexing, that's interesting ! In the meantime, I think we'll run both MF and SimVim since there were no conflicts when we did our last tests.

STOP !!!

My friend who's in charge of the hardware said he will try something else with the shield but splitting the power supply for the LCD Display

Why using a Power suply ???
A LCD and a couple of /Seg and some LED pretty sure not need this..... Can be done with USB power aslong the overall Power is less then 500mA

Whatever.... If you use a Power suply ( for the LCD) then get sure the GRD of that device is connected to the GRD Pin of the Mega ( Where you set the LCD on Pin 20/21.)
All Devices in the cockput MUST have the same GRD..... including all external Power supplys!

Additional i high recommend: NOT power the Mega itself with external supplys ( by the Port on the front) .... The Mega is powerd via 5V from USB.... You can "exclude" some devices with a own circuit..... But let the Mega itself out of that! ..... If really the USB get in trouble ( more then e.g. 3 Megas on a Port or lots of Megas in the system..... then use Powerd USB Hubs .....
So. Power to Mega itself ONLY via USB!

Get sure your Shield not use a external power that is also wired to the Mega itself !

I may not have expressed it clearly

I don't know what he has exactly in mind but I don't think it involves an external power supply.

Anyway, he's now taking another road since he doesn't want to redo the wiring of the cockpit (everything was made with PCBs and soldered wires). I must confessed I'm not convinced by this choice since it involves using dedicated libraries and plugins, and writing the code for the Arduino... so let's hope MobiFlight will soon support multiplexing