MobiFlight Community Support

Some weeks ago I decided I wanted to build a transponder for my X plane setup.
So I found this nice little transponder project online that looked doable for a complete novice.
https://cessna172sim.allanglen.com/docs/avionics/bendix-king-kt76c/
I have never built any instruments for my flight sim setup, but wanted to learn. I’ve discovered I have a lot to learn about the electronics.
My research led me to the Arduino mega 2560 controller board and Simvim for the integration.
To that end I have purchased the electrical components listed on that web site along with the 2560 controller. I also bought an electronics breadboard kit and soldering equipment for the build.
What I have accomplished so far is the installation of the Simvim Xplane plugin and then instead of installing the IDE software for the board I installed the Simvim firmware via Xplane onto the 2560 controller board.
Yesterday I learned about Mobiflight and it’s ability to connect with Xplane with XPUIPC and read some good reviews about how easy it is to use and configure..
So here are a couple of questions.
1. How do I change my Arduino from the Simvim Firmware to the IDE Firmware that the mobiflight tutorial I just saw mentions to use before configuring the Arduino with Mobiflight?
2. Is that BendixKing transponder in the link with the push buttons, the 8 digit 7 segment display and the rotary encoder something that will work with mobiflight and connect to the virtual transponder in the Xplane aircraft?

Hi

Basicly you can remove every software from those Arduinos. If its just a sketch you can simply rewrite it. If it´s in the EEPROM ( pretty sure) you use with the Arduino IDE the EEPROM Clear sketch to get the board "back to main state" . Then its "empty" and if you start our Mobiflight Software it will detect it and offer you to install now the Mobiflight Firmware.
( NOTE: Same situation inverted .... To remove the Mobiflight Software you need again this EEPROM Clear..... Then you can use it again for SimVom or so)


About your Parts Question:
The Display is compatible. for the Rotary i got no data sheet. Looks good but i can not garantee.
BUT: The Problem will be the "0-7" Buttons. Hardware Compatible but Software is problematic here.
With XPUIPC it is not directly possible to set the Transponder to a value by "number buttons". XPUIPC ( same way like FSUIPC for P3D and FSX) just allow to increase or decrease the Transponder whole Value or the single diggits..... Thats why most aircrafts uses 4 ( 2 or 1) Encoder for this and not something like a keypad.

On first view i would say.... Hardware is compatible.... You can controll lots of Xplane stuff with MF..... But the transponder in THAT way is not possible!

Last note..... Please remember.... SimVim is 100% based on Xplane as i know.... Mobiflight allow using XPlane, too BUT it´s designed for P3D/FSX/FS2020.
So to handle Xplane ( specialy with AddOn Aircrafts) you need programming skills to use Mobilflight !
Here SimVim is maybe the better choice finaly cause it directly talk to XP and not need the difficult bypass by XPUIPC!

So if I understand you correctly Mobiflight with FSUIPC or XPUIPC can only Simulate transponders like the one in the Just Flight Arrow in this link?

https://www.justflight.com/product/pa28r-arrow-iii-xplane-11

No not directly....
Mobiflight not have a limitation what is possible or a guideline that one kind of Transponders work and a other won´t work.

The Problem is... Are you be able to READ the needed stuff and to WRITE the needed Inputs ?

XPUIPC support us the official Sim Transponder Value ( that is set at the moment in the Radios)
But pretty sure a press on the 0-7 Buttons in those Transponders like you want to build will NOT directly write the Sim Transponder !
I think they will build a "temporary" variable ..... And after you enter the 4th digit it write this variable to the Sim Transponder and set it that way.

So in easy words.... You need to tell the Display it should show the sim Transponder value BUT if you press a button it should show now the "temporary varibale" until it´s finished.

Here the question is..... That variable is garantee not include in the XPUIPC Standard system..... so YOU need to write a line of code that read this variable from the Sim and support it to a Offset we can read with Mobiflight. Only possible if you find that variable and be able to read it !!

Here SimVim is more easy i think cause here as i know you can directly choose those varibales instead of writing code and go the bypass through a offset.
And same for the Buttons. Those have no Offset in XPUIPC.... You must build a system of Events or Offset Inputs ( via own code again) to make this possible.

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ALTERNATE:
With a tricky system and a lot of testing we can try to build this Transponder completly indipended via Mobiflight and some custom Offsets. I think this is possible. But this is a advanced project and pretty sure need some time !


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The code writing would be beyond my capabilities which is why Simvim seems to be a good solution.
Thanks for the clarification.

XPUIPC does not work well. Many variables are not exported, also the source code is unsupported and I cannot find it anywhere.

Paul