FS2020 - Switch/LED Panel with Arduino

A simple external switches and LEDs panel to manage some FS2020 (for PC) airplanes commands.

If you are a Flight Simulator enthusiast and would try to build your first external panel to send some commands and read some status from FS, probably you will be interested in this project because it's simple, flexible and cheap.

Unlike other solutions, this project will let you play with some Arduino programming code but don't need any development effort on the PC side. On the other end you will play also with some very simple hardware stuff other then an Arduino board of any type. The most important thing, however, is that with a very little effort, your panel can be highly customized to your needs by changing the function of each button/switch/LED or adding new ones.

A short video here: https://www.youtube.com/watch?v=05aUgwHtf3Q

Why this project

I'm quite a beginner in the Arduino world but i'm also really interested in flight both simulated and real (Ultralight Planes). Few years ago i bought 5 Arduino Nano to build a Star Tracker: a camera-holder capable to rotate at the same rotation speed of the earth. That project was a solution to take steady photos (with long exposures) of the stars during the night but for that project i used only 1 of my 5 Arduino boards.

Some months ago i bought the Microsoft Flight Simulator 2020 and i use it with a Saitek X52 (so i have a lot of buttons for the main commands) but after a while i realized that i was having some problems for:

reading the status of some parameters and values (for example on the Garmin display)
managing other FS commands using the mouse during the flight

So i decided to start this first project using one of the Arduino Nano that i had in my drawer, trying to reach a good software architecture before building a more complex solution to manage and display also numeric values (like frequencies, altitude, air speed, etc) in a second project.

At this time you can find also my second project here: https://github.com/IWILZ/FS2020-LCD-Panel

What it does

The panel manages and shows the state of:

flaps incrementing/decrementing them to max 4 positions
navigation lights (grouped in STROBE, NAV, BEACON, WING, LOGO, CABIN and PANEL)
landing lights (grouped in LANDING and TAXI)
pitot heat
rudder trim
engine(s) startup and shutdown with AUTO_START and AUTO_SHUTDOWN functions of simulator
in addition i have also a RESET button that is useful when starting the flight to be sure about the state of all the lights of the plane

Of course you can choose to use a different number of buttons and LEDs adapting hardware and software to manage/show different simulator commands and parameters.

The architecture

In the following picture you can see 3 components:

the switching panel (with Arduino and some buttons and LEDs)
a program (FS2020TA.exe) that manages the bidirectional communications with FS (you will find a link to this program later in this document)
the Flight Simulator itself

The panel reads values and send commands to FS using the FS2020TA.exe (made by Seahawk240) as a sort of communication "repeater". The Arduino board communicates with the PC and FS2020TA.exe (that uses a SimConnect.dll) using a standard USB port. The communication protocol is very simple and will be explaned later.

What you need

What you need is:

an ordinary Arduino board (not necessarily a Nano)
some switches and/or buttons
some LEDs and resistors
one or more small breadboards
a soldering iron
some small section wires to connect switches and LEDs to the Arduino board

Due to the small power consumption, the panel is simply powered by the 5Vcc of the USB connection and basically the only limit of the number of status LEDs and command buttons/switches is the number of I/O pin of the Arduino board you are using.

In my case i used 9 buttons/switches + 6 status LEDs. For the front panel i used a 15x8cm rectangle of a carbon fiber plate but you can use also a wood plate or anything else from about 1.5 to 3mm thick.

Optionally you can also use a little 5Vcc passive buzzer (see the next picture) just as a "sound confirmation" of any button-press whenever you send a command to FS2020.

For the components you will find some links at the end of this document.

Input/Output connections

Each Arduino pin can be configured as an Input or an Output by the program so all it's very flexible. Obviously every LED connection has to be an Output (any output pin produces a 5Vcc when in high level) and every button/switch an Input but in this last case the program have to configure it like an "INPUT_PULLUP" pin to avoid problems with random status reading.

In the following picture you can see how to connect a generic LED and a generic button/switch. Each button should be "normally opened" so it will "close the circuit" to the ground only when pressed.

About the resistor

To avoid a damage of the micro controller itself DON'T CONNECT A LED DIRECTLY to the Arduino, but use a resistor to limit the current flowing to the LED. The resistor value depends on the LED brand and colour (normally red ones need a lower value resistor than green ones) but you could start with a value of 1KOhm and then change it to find the right value/light for your LED. If you have a tester you can also measure the current flowing into the LED considering that the maximum current on a output PIN of the Arduino cannot never exceed 20mA. If you cannot measure the current, just look at your LED's light and don't exceed with its brightness.

The FS2020TA.exe

Yes this is the software "bridge" to make a bi-directional communication between Arduino and FS2020. The program is free, was developed by Matthias Schaaf and can be dwonloaded from: https://github.com/Seahawk240/Microsoft-FS2020-To-Arduino

FS2020TA.exe (wich uses SimConnect.dll) is very simple and strong and the communication is made using standard Serial functions. To get informations from FS you have to make a sort of list within FS2020TA and then you will use Serial.readStringUntil() into the Arduino sketch. In the same way to send commands you simply have to use Serial.print().

You can also find a video description here: https://www.youtube.com/watch?v=EVqY8KhdZI8 and for more informations, please read the official documentation from Matthias Schaaf.

About FS2020 variables, you can also find some useful info here: https://docs.flightsimulator.com/html/index.htm#t=Programming_Tools%2FSimVars%2FSimulation_Variables.htm

The communication protocol with FS2020TA

The communications is made simply sending and receiving strings over the USB connection of the PC.

Reading values/parameters from FS

Every parameter is received as a string using "Serial.readStringUntil()" and the format is "@ID/index=value$" where '@', '/', '=' and '$' are markers to identify the 3 field "ID", "index" and "value".

ID = idientifies each parameter
index = idientifies different objects having the same parameter. For example when ID=502 (NAV_ACTIVE_FREQUENCY), index=1 is for the frequency of NAV1 and index=2 is the same for NAV2. When there is only 1 object to identify, index=-1
value = is the value itself and can be interpreted as an integer, float, string, degree, boolean, etc depending of the kind of parameter

Of course depending on the "ID" value, the program has to manage "value" converting it from a string to a number if necessary.

In this project all we need are the following IDs:

/*************************************************************
              Parameter IDs from FS2020
 *************************************************************/
#define FLAPS_HANDLE_INDEX      247       // Flaps position (1...4)
#define LIGHT_NAV               468       // LIGHT NAV
#define LIGHT_LANDING           464       // LIGHT LANDING
#define LIGHT_STATES            474       // Light status mask

FS2020TA.exe sends continuously the above list of parameters ending each one with a '\n' (for example "@247/-1=2$\n" means that flaps are in second position).

Inside the main loop() of the sketch, the program calls GetParamFromFS2020() function that simply reads the next string until '\n' and stores "ID", "index" and "value" into 3 global variables. After that the program manage this parameter switching on/off a corresponding LED.

Just few words about LIGHT_STATES

LIGHT_STATES is a (unsigned int) binary mask using 10 bits showing the state of every light of the plane with the following meaning:

// --00 0000 0000 -> *********** ALL LIGHTS OFF *********** 
// --11 1111 1111 -> *********** ALL LIGHTS ON  *********** 
// --00 0000 0001 -> light NAV         -> group NAV
// --00 0000 0010 -> light BEACON      -> group NAV
// --00 0000 0100 -> light LANDING     -> group LAND
// --00 0000 1000 -> light TAXI        -> group LAND
// --00 0001 0000 -> light STROBE      -> group NAV 
// --00 0010 0000 -> light PANEL       -> group NAV 
// --00 0100 0000 -> light RECOGNITION -> group LAND (probably unuseful)
// --00 1000 0000 -> light WING        -> group NAV
// --01 0000 0000 -> light LOGO        -> group NAV
// --10 0000 0000 -> light CABIN       -> group NAV

In the program for simplicity i have collected the lights in 2 groups: NAV and LAND. So for example, by pressing the "NAV" button, the following lights are switched on or off all together: NAV, BEACON, STROBE, PANEL, WING, LOGO, CABIN.

Sending commands to FS

To send a command to FS you have just to send a string using Serial.print() and this is the list of all the commands we need:

/*************************************************************
              Definition of commands to FS2020
 *************************************************************/
#define FLAPS_INCR            "@289/$"  // 
#define FLAPS_DECR            "@287/$"  // 
#define ENGINE_AUTO_SHUTDOWN  "@272/$"  //
#define ENGINE_AUTO_START     "@273/$"  //
#define PITOT_HEAT_ON         "@620/$"  //
#define PITOT_HEAT_OFF        "@619/$"  //
#define RUDDER_TRIM_LEFT      "@722/$"  //
#define RUDDER_TRIM_RIGHT     "@723/$"  //

// --------------- Lights ------------------
#define LANDING_LIGHTS_ON     "@464/$"  //
#define LANDING_LIGHTS_OFF    "@463/$"  //
#define STROBES_ON            "@787/$"  //
#define STROBES_OFF           "@786/$"  //
#define PANEL_LIGHTS_ON       "@611/$"  //
#define PANEL_LIGHTS_OFF      "@610/$"  //

#define TOGGLE_BEACON_LIGHTS  "@854/$"  // 
#define TOGGLE_LOGO_LIGHTS    "@884/$"  // 
#define TOGGLE_NAV_LIGHTS     "@889/$"  // 
#define TOGGLE_WING_LIGHTS    "@918/$"  // 
#define TOGGLE_TAXI_LIGHTS    "@910/$"  // 
#define TOGGLE_CABIN_LIGHTS   "@855/$"  //

Define of I/O pins

Just to give you a bit more informations, i will show you wich pin i use in my project, but if you want change your Arduino board or for some other reasons you want to change your pins you will just change their "defines" accordingly.

/*************************************************************
            Buttons and switches input pins
 *************************************************************/
#define IN_ENGINE_START       2
#define IN_ENGINE_STOP        3
#define IN_FLAPS_DEC          4
#define IN_FLAPS_INC          5
#define IN_PITOT_HEAT         6   // Switch 
#define IN_LIGHTS_NAV         7
#define IN_LIGHTS_LAND        8
#define IN_RUDDER_TRIM_RIGHT  10
#define IN_RUDDER_TRIM_LEFT   11

/*************************************************************
                     LEDs output pins
 *************************************************************/
#define OUT_LIGHTS_LAND       A0
#define OUT_LIGHTS_NAV        A1
#define OUT_FLAPS_1           A5 
#define OUT_FLAPS_2           A4
#define OUT_FLAPS_3           A3
#define OUT_FLAPS_4           A2

// ************** Optional buzzer on PIN 9 ****************
// To activate it uncomment the following line
//#define BUZZER_CONNECTED
#define BUZZER_PIN            9 // Pin 9 for the buzzer

IWILZ / FS2020-Switch-Panel