Hi fellow wiki editors!

To help newly registered users get more familiar with the wiki (and maybe older users too) there is now a {{Welcome to the wiki}} template. Have a look at it and feel free to add it to new users discussion pages (and perhaps your own).

I have tried to keep the template short, but meaningful. /Johan G

Changes

Jump to: navigation, search

Howto:Use Arduino with FlightGear

14,761 bytes added, 16:24, 17 June 2019
Add updated changes and some potential pitfalls
Thanks to FlightGear's [[generic protocol]], [[:Category:Hardware|hardware]] can easily interface with [[FlightGear]]. This hardware can be used to improve the immersion and/or realism of the simulation. Arduino is no exception.
 
== About Arduino ==
'''[http://www.arduino.cc/ Arduino]''' is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. The hardware is a microcontroller designed around an 8-bit or 32-bit microcontroller, with several digital and analog {{Abbr|I/O|Input/Output}} ports. The software is the [http://arduino.cc/en/Main/Software Arduino {{Abbr|IDE|Integrated Development Environment}}].
 
== Example 1: 2-axis joystic ==
<big>By ScottBouch</big>
 
This example demonstrates use of two potentiometers (2-axis joystic) with a simple calibration in arduino code. Example is done with Linux Mint. To see more detailed version of this quide go to [http://www.scottbouch.com/flightgear-sim-arduino-serial-hardware-2-axis-potentiometer-joystick.html 2-Axis Potentiometer Joystick:Integration With Flightgear Flight Sim].
 
=== Wiring ===
Connect 5V to other terminal of potentiometers and 0V to other terminal. Connect potentiometers wiper terminals to Arduino boards A0 and A1.
 
=== Arduino code ===
<syntaxhighlight lang="c">
/*
Flightgear hardware integration 01: Stick X and Y only so far.
 
Scott Bouchard UK www.scottbouch.com 14-06-2017
*/
 
const int stickxio = A0; //Define stick aileron (x) input
const int stickyio = A1; //Define stick elevator (y) input
 
float stickx = 0; //Start aileron (x) central
float sticky = 0; //Start elevator (y) central
 
void setup() {
Serial.begin(9600); //Open up serial communication to PC
}
 
void loop() {
stickx = (analogRead(stickxio)/512.0)-0.99; //Calibration span and offset
sticky = (analogRead(stickyio)/512.0)-0.99; //Calibration span and offset
 
Serial.print(stickx); //Send aileron position
Serial.print(","); //Variable (var) separator
Serial.print(sticky); //Send elevator position
Serial.print("\n"); //Line separator
}
</syntaxhighlight>
=== Calibration ===
Use Arduino serial monitor to see that serial data acquired from Arduino board is between -1.00...1.00 when potentiometers are rotated. Potentiometers middle position should send 0.00. If potentiometers are not giving good readings, modify Arduino code "Calibration span and offset" row to fix it.
 
=== Flightgear protocol code ===
Create a file called hardware.xml to /usr/share/games/flightgear/Protocol directory and paste following lines to it:
 
<syntaxhighlight lang="xml">
<?xml version="1.0"?>
 
<PropertyList>
 
<generic>
 
<input>
<line_separator>\n</line_separator>
<var_separator>,</var_separator>
 
<chunk>
<name>aileron</name>
<type>float</type>
<node>/controls/flight/aileron</node>
</chunk>
 
<chunk>
<name>elevator</name>
<type>float</type>
<node>/controls/flight/elevator</node>
</chunk>
 
</input>
 
</generic>
 
</PropertyList>
</syntaxhighlight>
 
=== Make Flightgear to read serial data ===
Find port where Arduino is connected. Look from Arduino IDE Tools... Serial Port... Should be something like ttyACM. (Note: Scott Bouch tutorial uses FGRUN which is not used anymore) Start Flightgear and paste following code to Settings... Additional settings... when starting Flightgear. Change serial port to correct port name.
 
<syntaxhighlight>
--generic=serial,in,30,/dev/ttyACM0,9600,hardware.xml
</syntaxhighlight>
 
== Example 2: Controlling internal properties ==
<big>By {{usr|Vaipe}}</big>
 
This example demonstrates the use of a switch and a potentiometer to control the [[Property Tree]].
 
=== Equipment and software ===
The following equipment was used for this example:
* [[Changelog_3.2|FlightGear 3.2]]
* [[FGRun]]
* [[Cessna 172P|Cessna 172P Skyhawk]] (default aircraft)
* [http://arduino.cc/en/Main/ArduinoBoardUno Arduino Uno]
* Linux ([http://en.wikipedia.org/wiki/List_of_Ubuntu_releases#Ubuntu_10.04_LTS_.28Lucid_Lynx.29 Ubuntu 14.04])
* Simple on/off switch
* Potentiometer
 
=== Input protocol file ===
Input protocol file is used to specify how serial information is read by Flightgear. In Ubuntu protocol files are found in:
<code>''/usr/share/games/flightgear/protocol''</code> directory.
 
==== Protocol file structure ====
Create <code>''controltest.xml''</code> file in your protocol folder and paste code from below to it.
<syntaxhighlight land="xml">
<?xml version="1.0"?>
 
<PropertyList>
 
<generic>
<input>
<line_separator>\n</line_separator>
<var_separator>,</var_separator>
<chunk>
<name>Strobe</name>
<node>/controls/lighting/strobe</node>
<type>bool</type>
</chunk>
<chunk>
<name>Throttle</name>
<node>/controls/engines/engine/throttle</node>
<type>float</type>
</chunk>
</input>
</generic>
 
</PropertyList>
</syntaxhighlight>
See [[Generic protocol]] for a description of the various XML tags.
 
=== Wiring and coding ===
 
==== Wiring ====
A potentiometer is connected to Arduinos ground and +5 volts. The potentiometer's middle connector is connected to A0 analoq input. Switch is connected to ground with 10 kOhms pull-down resistor and +5 and digital pin 7. The diagram below illustrates the setup.
[[File:Arduino switch and potentiometer wiring.png|frame|none|Wiring schematic for connecting the potentiometer and switch to Arduino]]
 
==== Code ====
Copy this C code to Arduino IDE and send it to the Arduino Uno:
<syntaxhighlight lang="c">
/*
FGFS Input Test
Reads a digital input on pin 7, prints the result to the serial port.
Reads a potentiometer input on A0 and print result to serial port.
This example code is in the public domain.
*/
int potPin = 0; // potentiometer on A0
int switchPin = 7; // switch on pin 7
float potValue = 0; // float variable to store potentiometer value
void setup() {
Serial.begin(9600); // open serial connection
pinMode(switchPin, INPUT); // pin 7 declared as input
}
void loop() {
Serial.print(digitalRead(switchPin)); // read and print switch state
Serial.print(","); // print ,
potValue = analogRead(potPin); // read potentiometer and store it to potValue
potValue = potValue / 1024; // divide potValue with 1024 to make it between 0 and 1
PrintDouble(potValue, 2); // pass potValue to PrintDouble-function, read from below what magic happens
Serial.print("\n"); // print new line
delay(500); // delay only for making this guide easier to follow on serial monitor
}
void PrintDouble(double val, byte precision){
// prints val with number of decimal places determine by precision
// precision is a number from 0 to 6 indicating the desired decimial places
// example: lcdPrintDouble( 3.1415, 2); // prints 3.14 (two decimal places)
// From http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1207226548
if(val < 0.0){
Serial.print('-');
val = -val;
}
Serial.print (int(val)); //prints the int part
if( precision > 0) {
Serial.print("."); // print the decimal point
unsigned long frac;
unsigned long mult = 1;
byte padding = precision -1;
while(precision--)
mult *=10;
if(val >= 0)
frac = (val - int(val)) * mult;
else
frac = (int(val)- val ) * mult;
unsigned long frac1 = frac;
while( frac1 /= 10 )
padding--;
while( padding--)
Serial.print("0");
Serial.print(frac,DEC) ;
}
}
</syntaxhighlight>
 
==== Testing serial output ====
Use Arduino IDE's serial monitor and you should see something like this:
[[File:Flightgear arduino serial monitor.png|frame|none|Arduino IDE's serial monitor output]]
 
The first number is switch data, so it's either 0 (switch off) or 1 (switch on). After the "," mark is our throttle data. First it's 0.00, which meaning idle throttle and then potentiometer is gradually turned until it reaches 0.99.
 
{{Note|Remember to '''unplug Arduino's USB cable and plug it back'''.
 
FlightGear will not be able to read serial without doing this!
 
You have to do this every time after you use the Arduino IDE.}}
 
{{Note|The above note may not be relevant to newer versions of the Arduino IDE software.}}
 
==== Starting FlightGear ====
 
===== Method 1: Command line =====
FlightGear needs to be started with a correct command line option for it to be able to read serial connection. This example uses following option:
<syntaxhighlight>
--generic=serial,in,30,/dev/ttyACM0,9600,controltest
</syntaxhighlight>
 
===== Method 2: FGRun =====
Alternatively, you can use FlightGear's graphical user interface (FGRun) to launch FlightGear. See the image below for the correct settings.
[[File:Starting Flightgear with input options enabled.jpg|thumb|none|Starting Flightgear with FGRun, selecting input/output options]]
 
If you don't know your correct port is , you can check it with a following command in terminal:
<syntaxhighlight>
dmesg | tail
</syntaxhighlight>
It should give you a message something like <code>ttyACM0: USB ACM device</code> or <code>ttyACM1: USB ACM device</code>.
 
{{Note|This command gives you the last event in the stack,
 
so you need to make sure you plug in or unplug your Arduino to the serial port
 
immediately prior to running the command.}}
 
That is your port. Finally, save setting by clicking "OK" and click "Run" to start FlightGear. For a more detailed guide, see [https://sites.google.com/site/flightgeararduinoandlinux/home Flightgear, Arduino and Linux]
 
{{Note|In some installations you need set permission for $user
 
to the groups tty and dialout or the Arduino will fail to
 
establish a connection to FlightGear.}}
 
== Example 3: Outputting properties ==
<big>By {{usr|Rubdos}}</big>
[[File:Arduinofgfs.jpg|thumb|270px|Arduino LCD panel displaying speed, heading and altitude.]]
'''This example uses the example using the [[Generic protocol]] and an [http://arduino.cc/en/Main/arduinoBoardMega2560 Arduino''' Mega 2560].Below is an openthe protocol XML file used to control the Arduino.<syntaxhighlight lang="xml"><?xml version="1.0"?> <PropertyList> <generic> <output> <binary_mode>false</binary_mode> <line_separator>newline</line_separator> <var_separator>newline</var_separator> <preamble></preamble> <postamble></postamble>  <chunk> <name>Altitude</name> <node>/position/altitude-source electronics prototyping platform based on flexible, easyft</node> <type>integer</type> <format>altitude=%i</format> </chunk>  <chunk> <name>RPM</name> <node>/engines/engine/rpm</node> <type>integer</type> <format>rpm=%i</format> </chunk>  </output>  <!-to-use [[<input> <line_separator>newline</line_separator> <var_separator>tab</var_separator> <chunk> </chunk> </input> --> </generic> </PropertyList></syntaxhighlight> Below is the C code used for the example, taken from https:Category//gist.github.com/rubdos/5422870.<syntaxhighlight lang="c">//PIN 0 -> 7 has positive segment part // the setup routine runs once when you press reset:Hardware|hardware]] void setup(consisting of a board designed around ) { // initialize the digital pin as an output. pinMode(2, OUTPUT); pinMode(3, OUTPUT); pinMode(4, OUTPUT); pinMode(5, OUTPUT); pinMode(6, OUTPUT); pinMode(7, OUTPUT); pinMode(8-bit or a 32-bit microcontroller, OUTPUT) and software ; pinMode(based on an integrated development environment 9, OUTPUT);   pinMode(IDE49, OUTPUT); pinMode(50, OUTPUT); pinMode(51, OUTPUT); pinMode(52, OUTPUT); pinMode(53, OUTPUT); Serial.begin(9600);[[FlightGear]]'s IO interface allows easy development of hardware that can improve } void writeNumber(int nr){ if(nr == 0) { digitalWrite(2, LOW); // midden digitalWrite(3, HIGH); // lt digitalWrite(4, HIGH); // t digitalWrite(5, HIGH); // rt digitalWrite(6, HIGH); // lb digitalWrite(7, HIGH); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 1) { digitalWrite(2, LOW); // midden digitalWrite(3, LOW); // lt digitalWrite(4, LOW); // t digitalWrite(5, HIGH); // rt digitalWrite(6, LOW); // lb digitalWrite(7, LOW); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 2) { digitalWrite(2, HIGH); // midden digitalWrite(3, LOW); // lt digitalWrite(4, HIGH); // t digitalWrite(5, HIGH); // rt digitalWrite(6, HIGH); // lb digitalWrite(7, HIGH); // b digitalWrite(8, LOW); // rb digitalWrite(9, LOW); // dot } else if(nr == 3) { digitalWrite(2, HIGH); // midden digitalWrite(3, LOW); // lt digitalWrite(4, HIGH); // t digitalWrite(5, HIGH); // rt digitalWrite(6, LOW); // lb digitalWrite(7, HIGH); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 4) { digitalWrite(2, HIGH); // midden digitalWrite(3, HIGH); // lt digitalWrite(4, LOW); // t digitalWrite(5, HIGH); // rt digitalWrite(6, LOW); // lb digitalWrite(7, LOW); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 5) { digitalWrite(2, HIGH); // midden digitalWrite(3, HIGH); // lt digitalWrite(4, HIGH); // t digitalWrite(5, LOW); // rt digitalWrite(6, LOW); // lb digitalWrite(7, HIGH); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 6) { digitalWrite(2, HIGH); // midden digitalWrite(3, HIGH); // lt digitalWrite(4, HIGH); // t digitalWrite(5, LOW); // rt digitalWrite(6, HIGH); // lb digitalWrite(7, HIGH); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 7) { digitalWrite(2, LOW); // midden digitalWrite(3, LOW); // lt digitalWrite(4, HIGH); // t digitalWrite(5, HIGH); // rt digitalWrite(6, LOW); // lb digitalWrite(7, LOW); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 8) { digitalWrite(2, HIGH); // midden digitalWrite(3, HIGH); // lt digitalWrite(4, HIGH); // t digitalWrite(5, HIGH); // rt digitalWrite(6, HIGH); // lb digitalWrite(7, HIGH); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else if(nr == 9) { digitalWrite(2, HIGH); // midden digitalWrite(3, HIGH); // lt digitalWrite(4, HIGH); // t digitalWrite(5, HIGH); // rt digitalWrite(6, LOW); // lb digitalWrite(7, HIGH); // b digitalWrite(8, HIGH); // rb digitalWrite(9, LOW); // dot } else { digitalWrite(2, LOW); // midden digitalWrite(3, LOW); // lt digitalWrite(4, LOW); // t digitalWrite(5, LOW); // rt digitalWrite(6, LOW); // lb digitalWrite(7, LOW); // b digitalWrite(8, LOW); // rb digitalWrite(9, LOW); // dot }} // the immersion loop routine runs over and realism of the simulation. The output [over again foreverlong number = 0;int decimals[Generic protocol|protocols5]] allow hardware to response to simulation data = {0, 0, 0, 0, 0}; void loop(like shown in ) { for(int i = 49; i < 54; i++) { // Disable the image on the rightincorrect segment displays if(i == 49) { digitalWrite(53, while HIGH); } else { digitalWrite(i - 1, HIGH); } digitalWrite(i, LOW); // Enable the input protocol allows FlightGear to reply to hardware events segments writeNumber(egdecimals[4 - (i - 49)]); delay(1); } if(Serial. on the press of a buttonavailable()> 14) // Wait until there are two bytes available.Then read them out. { String command; String var; char lastchar;
while(lastchar !='= Display') { lastchar = Serial.read(); if(lastchar != '=') { command += lastchar; } } while(lastchar != '\n') { lastchar = Serial.read(); if(lastchar != '\n') { var += lastchar; } } if(command == "altitude" ) { char buf[50]; var.toCharArray(buf, 50); number = atol(buf); } /Generic protocol Example by rubdos *if(number ==10000) { number = 0; }*/ long currentnumber = number; int remainder = currentnumber % 10; currentnumber = (currentnumber - remainder) / 10; decimals[4] = remainder; remainder = currentnumber % 10; currentnumber = (currentnumber - remainder) / 10; decimals[3] = remainder; remainder = currentnumber % 10; currentnumber = (currentnumber - remainder) / 10; decimals[2] = remainder; remainder = currentnumber % 10; currentnumber = (currentnumber - remainder) / 10; decimals[1] = remainder; remainder = currentnumber % 10; currentnumber = (currentnumber - remainder) / 10; decimals[0] = remainder; }}</syntaxhighlight>
Rubdos (Ruben De Smet) has built an example using the [[Generic Protocol]] and an Arduino Mega 2560.The code hardware used to control was five seven-segment displays, multiplexed straight on the Arduino with generic protocol was: <?xml version="1device.0"?> <PropertyList> <generic> <output> <binary_mode>false</binary_mode> <line_separator>newline</line_separator> <var_separator>newline</var_separator> <preamble></preamble> <postamble></postamble> <chunk> <name>Altitude</name> <node>/position/altitude-ft</node> <type>integer</type> <format>altitude=%i</format> </chunk> <chunk> <name>RPM</name> <node>/engines/engine/rpm</node> <type>integer</type> <format>rpm=%i</format> </chunk> </output> <!-- <input> <line_separator>newline</line_separator> <var_separator>tab</var_separator> <chunk> </chunk> </input> --> </generic> </PropertyList>It is a simple plaintext protocolIdeally, which can easily be parsed by an Arduino. The code used on you'd rather use some 74HC595 or other shift register chips to drive them, to unload the Arduino is available on github as a gist: [https://gist.githuband have more current.com/rubdos/5422870]
As hardware, five seven segment displays were used, multiplexed straight on the Arduino device. In production, you'd rather use some 74HC595 or other shift register chips to drive them, to unload the Arduino and have more current.A Below is a demo is uploaded to youtubeYouTube, with voiceover in which the display shows the RPM of the first engine of (the single engine) [[Robin DR400]]'s single engine.{{#ev: [https://www.youtube.com/watch?v=|lVtV9-CgqBo]}}
== Related content ==
== External links ==
* [http://arduino.cc/ Official Arduino website]
* [http://playground.arduino.cc/Main/FlightGear FlightGear Serial Communications with Arduino] (tutorial)
* [http://forum.flightgear.org/viewtopic.php?f=18&t=11126 Arduino LCD and FlightGear] (FlightGear forum)
255
edits

Navigation menu