Arduino + Unity communication made easy

And not just Arduino: any hardware/software that communicates over serial (COM) ports !

WebSite URL: https://ardity.dwilches.com

(Previously known as: SerialCommUnity)

There are three scenes that show how to read/write data from/to a serial device. There is a prefab that you need to add to your scene, this prefab will do all the thread management, queue synchronization and exception handling for you.

If you need a program to test your Unity scene I have created the following Arduino program that sends a heartbeat message each 2 seconds. It also recognizes two input messages and reacts to them, this is for bidirectional communication for the scene "DemoSceneUserPoll_ReadWrite". So if you want to use that scene just run it and press the keys 'A' or 'Z' to see what you Arduino has to say about it.

This sample communicates with any of the scenes called: DemoScene_AutoPoll* or DemoScene_UserPoll*.

unsigned long last_time = 0;

void setup()
{
    Serial.begin(9600);
}

void loop()
{
    // Print a heartbeat
    if (millis() > last_time + 2000)
    {
        Serial.println("Arduino is alive!!");
        last_time = millis();
    }

    // Send some message when I receive an 'A' or a 'Z'.
    switch (Serial.read())
    {
        case 'A':
            Serial.println("That's the first letter of the abecedarium.");
            break;
        case 'Z':
            Serial.println("That's the last letter of the abecedarium.");
            break;
    }
}

This sample has a tear-down function (use it with the scene DemoScene_SampleTearDown), it will be executed when the Unity program stops. This sample expects you to be using an Arduino UNO, if not, change the number of the pin to which the LED is connected.

unsigned long last_time = 0;
int ledPin = 13;

void setup()
{
    Serial.begin(9600);
    pinMode(ledPin, OUTPUT);
    digitalWrite(ledPin, LOW);
}

void loop()
{
    // Print a heartbeat
    if (millis() > last_time + 2000)
    {
        Serial.println("Arduino is alive!!");
        last_time = millis();
    }

    // Send some message when I receive an 'A' or a 'Z'.
    switch (Serial.read())
    {
        case '1':
            digitalWrite(ledPin, HIGH);
            Serial.println("Lights are ON");
            break;
        case '2':
            digitalWrite(ledPin, LOW);
            Serial.println("Lights are OFF");
            break;
        
        // Execute tear-down functionality
        case 'X':
            for (int i = 0; i < 10; i++)
            {
                digitalWrite(ledPin, HIGH);
                delay(100);
                digitalWrite(ledPin, LOW);
                delay(100);
            }
            
            // This message won't arrive at Unity, as it is already in the
            // process of closing the port
            Serial.println("Tearing down some work inside Arduino");
            break;
    }
}

// This is the separator configured in Unity
#define SEPARATOR 255

unsigned long last_time = 0;
int ledPin = 13;

byte responseMessage[] = { 65, 66, 67, SEPARATOR };
byte aliveMessage[] = { 65, 76, 73, 86, 69, 33, SEPARATOR };

void setup()
{
    Serial.begin(9600);

    aliveMessage[8] = SEPARATOR;
}

void loop()
{
    // Print a heartbeat
    if (millis() > last_time + 2000)
    {
        Serial.write(aliveMessage, sizeof(aliveMessage));
        Serial.flush();
        last_time = millis();
    }
    
    // React to "commands"
    if (Serial.read() == ' ')
    {
        Serial.write(responseMessage, sizeof(responseMessage));
        Serial.flush();
    }
}

Ardity is quite simple to use. You can find the setup guide in PDF format here.

There is also a series of in-depth tutorials by the Interface Lab from the University NYU Shanghai, please take a look here:

• Connecting to Unity
• Working with many sensors
• Bidirectional communication

To open a COM port from Ardity you need to use one of these naming conventions:

• COM1, COM2, ... for COM1 through COM9
• \\.\COM10, \\.\COM11, ... for COM10 and up

Yes, it's possible. You need to configure your device to be seen in your operating system as a COM port. Instructions to do so vary from device to device and from OS to OS. Once you have it configured, use that COM port with Ardity, which will treat it as just another serial device.

If you get this error:

Assets/Ardity/Scripts/SerialThread.cs(9,17): error CS0234: The type or namespace name 'Ports' does not exist in the namespace 'System.IO'. Are you missing an assembly reference?

Check the current "API Compatibility Level" of your Unity project. Go to Edit -> Project Settings -> Player, and under Other Settings find an option that reads "Api Compatibility Level" and change it to .NET 4.0 (or .NET 2.0 if you have a version older than Unity 2018).

Also, some users have reported needing to manually add System.IO.dll to the project. If the above solution doesn't work for you, in Visual Studio go to Project -> Add Reference -> Browse and then select the file System.IO.dll from inside your .NET framework's folder. This file may be located at C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\Facades\System.IO.dll.

Some users have reported needing to enable RtsEnable and DtsEnable in order to get Ardity to work with their devices. So if communication is not working for you, try enabling these options in AbstractSerialThread just before the serialPort.Open() invocation:

serialPort.DtrEnable = true;
serialPort.RtsEnable = true;

Try changing the scripting backend from Mono to IL2CPP.

This work is released under the Creative Commons Attributions license.

If you use this library please let me know, so I know my work has been useful to you :)