Unity Arduino Input/Output

ArduinoSerialIO.cs

/* Arduino Serial I/O
 * Allows you to send simple commands to an arduino and to receive data back.
 * 
 * Source based on: https://www.alanzucconi.com/2015/10/07/how-to-integrate-arduino-with-unity/
 *
 * ## Setup
 * 1. Edit > Player Settings
 * 2. .NET Compatibility Level = `.NET 2.0`
*/

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.IO.Ports;

public class ArduinoIO : MonoBehaviour {

	// User Inputs
	[Tooltip("Open Arduino serial monitor, and look for the name of the port at the end of the phrase 'Arduino/Genuino Uno at...")]
	public string portName = "COM5";

	[Tooltip("The baudrate of the serial port")]
	public int baudrate = 9600;

	public int outputValue = 0;

	// Storage & I/O
	private SerialPort stream;

	public void Open () {
		// Opens the serial port
		stream = new SerialPort(portName, baudrate);
		stream.ReadTimeout = 20;
		stream.Open();
		WriteToArduino ("INIT");
		//this.stream.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
	}

	public void WriteToArduino(string message)
	{
		// Send the request
		stream.WriteLine(message + '\n');
		stream.BaseStream.Flush();
	}

	public string ReadFromArduino()
	{
		try
		{
			return stream.ReadLine();
		}
		catch
		{
			return null;
		}
	}

	// Use this for initialization
	void Start () {
		Open ();
	}

	// Update is called once per frame
	void Update () {
		WriteToArduino ("DIST");
		try{
			string arduinoOutput = ReadFromArduino();
			outputValue = int.Parse (arduinoOutput);	
		}
		catch{
		}

		if (outputValue != -1) {
			Vector3 immediatePostion = new Vector3 (0.0f, (float)outputValue * 0.1f, 0.0f);
			transform.position = Vector3.Lerp(transform.position, immediatePostion, 0.75f);
		}
	}
}

UltrasonicSensorOutput.ino

/* SerialOutput.ino
Outputs simple commands to the Serial port based on the readings from an Ultrasonic Range Sensor
Using: HCS-SRO4

## Commands
- `INIT`: Flashes the Arduino's built-in LED 3, 2, 1 times.
- `DEBUG`: Writes sensor data to Serial in an unending stream.
- `END`: Stops `DEBUG` mode.
- `DIST`: Writes the current distance reading to the stream once.
*/

// Library Imports
#include <NewPing.h> // This is the Ultrasonic Sensor library
#include <RunningMedian.h> // This is a running median filter library

// Hardware Setup
#define BAUD_RATE 9600

const int TRIGGER_PIN = 2; //The pin attached to trig
const int ECHO_PIN = 3;   // the pin attached to echco
const int MAX_DISTANCE = 65; // Measured in Centimeters
long distance; // I hope there aren't extra charges! :-P

// Message Properties
const char eomChar = '\n'; // The end of message terminator. Necessary for serial.readStringUntil to prevent timeout
String message;

// Setup Connection
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // Define "sonar" instance of Newping with parameters

// Data Smoothing
RunningMedian samples = RunningMedian(15); // Define "samples" instance of RunningMedian with 15 sample parameter

// Debug
bool debug = false;

void setup() {
  // Open Serial Connection
  Serial.begin(BAUD_RATE);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
  // Reads input from Ultrasonic Rangefinder
  
  // Read bytes from serial buffer if any
  if (Serial.available()) {
    message = Serial.readStringUntil(eomChar);
    
    if (message == "DIST"){
      printDistance();
    }
    
    else if (message == "INIT"){
      ledCountDown();
    }
    
    else if (message == "DEBUG"){
      debug = true;
    }
    
    else if (message == "END"){
      debug = false;
    }
  }
  
  if (debug) {
    printDistance();
  }
  
  // Return the current distance measurement in cm
  distance = sonar.ping_cm();
  
  // Add current distance measurement to median filter
  samples.add(distance);

}

void ledCountDown(){
  // Countdown
  int flashCount = 3;
  int flashPeriod = 200;
  int flashBreak = 500;
  
  for (int count=flashCount; count>0; count--)
  {
    for (int j=0; j<count; j++){
      digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
      delay(flashPeriod);
      digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
      delay(flashPeriod);
    }
    
    delay(flashBreak);
  }
}

void printDistance () {
  /* Retrieves distance from cached values. Outputs it to the serial port. 
  * Message code: "DIST"
  */

  int cm = samples.getMedian(); //return median distance from filter

  if (cm <= MAX_DISTANCE)
    Serial.println(cm); //send value if less than 65
  else
    Serial.println(-1); //else send string
}

Added comments. Some minor refactoring. Removed the while(); block in setup().

Added realtime printing when "DEBUG" command is sent.