Arduino & Unity3d

Interfacing through USB









A micro-talk by @Robin_B

Approaches


Serial

MIDI

Joystick

Serial communication

Pros:
+ Works on standard Arduinos
+ Built-in support in Unity3D

Cons:
- Byte-based, need to do parsing
- Unity implementation of Serial is buggy and incomplete
- I had weird bluescreens using threads in Unity

Serial: Sending from Arduino


Sending:
 void setup()
{
	Serial.begin(9600);	Serial.println("hello");}

void loop()
{}

Serial: Receiving on Arduino

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

void loop() 
{
        if (Serial.available() > 0) 
        {
                byte incomingByte = Serial.read();

                Serial.print("I received: ");
                Serial.println(incomingByte, DEC);
        }
}



Ref: http://arduino.cc/en/Serial/read

Serial on Unity3d

Switch to full .NET 2.0 compatibility
(Edit - Project Settings - Player)

Serial on Unity3d


Reading a line from a Serial COM Port in Unity:
SerialPort stream = new SerialPort("COM4", 9600);

void Start () 
{	stream.Open(); //Open the Serial Stream.
}
  
void Update () 
{
    string value = stream.ReadLine(); //Read the information
    string[] data = value.Split(','); 
    // ...
}

Serial in Unity


Random bits:
- Get all port names with SerialPort.GetPortNames()
- Set low readline timeout with stream.ReadTimeout() to avoid locking the program (or use threading)
- Arduino Serial Monitor will block serial port, close it before running your unity script
- 

Interlude: Teensy


Arduino compatible microchip, ca. £20, http://www.pjrc.com/teensy/

Interlude: Teensy

Advantages over other Arduinos:
- More everything (analog & digital ports, speed, memory,  analog accuracy)
- 12 touch sensitive pins
- Can act as USB Joystick, Keyboard, Mouse, MIDI device

Drawback: 3.3V architecture (some accessories expect 5V signals)

Enabling Special Teensy USB Modes


Joystick

Pros:
- Plug & Play
- Directly control 6 joystick axes & 32 buttons, 1 Hat Switch

Cons:
- Not very expandable
- Teensy only (Arduino clone)
- One way communication


More info: http://www.pjrc.com/teensy/td_joystick.html
(or google "teensy joystick")

Joystick: Sending

Teensy Example:
void setup() {}

void loop() 
{	Joystick.X(512); // from 0 - 1023, center at 512
	Joystick.Y(1);

	Joystick.button(1, 1);
	delay(100);
	Joystick.button(1, 0);
	delay(100);
}

In Unity3D: 
Configure joystick using Input Manager  (Edit - Project Settings - Input Manager)
Then Input.GetAxis("axisname") or Input.GetButton("buttonname")

MIDI

Pros:
+ Bidirectional communication
+ Simple management of 256+ different controls

Cons:
- Standard accuracy only 7 bit (0-127)
- Requires some work to get into Unity

Midi: Unity3d

How to get MIDI into Unity3D:

- Unity Pro plugin: MIDI Unified ($90)

- Unity Free requires a 'bridge' to interact with MIDI
https://github.com/keijiro/unity-midi-bridge
Win + Mac command line tool that sends midi commands between Arduino (Teensy) and the MidiController in Unity.

(demo)

Midi: Arduino (Teensy) side


Sending data:
void setup() 
{
}

void loop() 
{
	usbMIDI.sendControlChange(
		1, 		// control (0-255)		50, 		// value (0-127)		1); 		// channel (0-15)}

MIDI: ARDUINO (TEENSY) SIDE


Receiving data:
 
void setup() 
{
	usbMIDI.setHandleControlChange(OnControlChange);
}

void OnControlChange(byte channel, byte control, byte value)
{
	// do something when receiving control data
}

void loop() 
{
}

MIDI: Sending Data from Unity


MidiOut and MidiInput are scripts provided with the midi-bridge.
Sending:
 MidiOut.SendControlChange(MidiChannel.Ch1, control, value);

Receiving:
 float input = MidiInput.GetKnob (channel, knobNumber); // 0.0f - 1.0f

Resources


Slides & Sliders: http://h3h.de

I'm on Twitter: @Robin_B
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