Processing / Reading Serial Port Data Streams Crashing Program

I'm working on a simple program to read a continuous stream of data from a plain old serial port. The program is written in Processing. Performing a simple read of data and dumping into to the console works perfectly fine, but whenever I add any other functionality (graphing,db entry) to the program, the port starts to become de-synchronized and all data from the serial port starts to become corrupt.

The incoming data from the serial port is in the following format :

A [TAB] //start flag

Data 1 [TAB]

Data 2 [TAB]

Data 3 [TAB]

Data 4 [TAB]

Data 5 [TAB]

Data 6 [TAB]

Data 7 [TAB]

Data 8 [TAB]

COUNT [TAB] //count of number of messages sent

Z [CR] //end flag followed by carriage return

So as stated, if I run the program below and simply have it output to the console, it runs fine without issue for several hours. If I add the graphing functionality or database connectivity, the serial data starts to come in garbled and serial port handler is never able to decode the message correctly again. I've tried all sorts of workarounds to this issue, thinking it is a timing problem but reducing the speed of the serial port doesn't seem to make a change.

If you see the serial port handler, I provide a large buffer just in case the terminating Z character is chopped off. I check to make sure the A and Z characters are in the correct place and in turn that the created "substring" is the correct length. When the program starts to fail, the substring will continuously fail this check until the program just crashes. Any ideas? I've tried several different ways of reading the serial port and am just beginning to wonder if I am missing something stupid here.

//Serial Port Tester
import processing.serial.*;
import processing.net.*;
import org.gwoptics.graphics.graph2D.Graph2D;
import org.gwoptics.graphics.graph2D.traces.ILine2DEquation;
import org.gwoptics.graphics.graph2D.traces.RollingLine2DTrace;
import de.bezier.data.sql.*;

SQLite db;
RollingLine2DTrace r1,r2,r3,r4;
Graph2D g;
Serial mSerialport;                    //the serial port
String[] svalues = new String[8];      //string values
int[] values = new int[8];             //int values
int endflag = 90;       //Z
byte seperator = 13;  //carriage return

class eq1 implements ILine2DEquation {
  public double computePoint(double x,int pos) {
    //data function for graph/plot
    return (values[0] - 32768);
  }
}

void connectDB()
{
  db = new SQLite( this, "data.sqlite" );  
  if ( db.connect() )
  {
    db.query( "SELECT name as \"Name\" FROM SQLITE_MASTER where type=\"table\"" );
    while (db.next())
    {
      println( db.getString("Name") );
    }
  }
}

void setup () {
  size(1200, 1000);        
  connectDB()开发者_运维百科;
  println(Serial.list());
  String portName = Serial.list()[3];
  mSerialport = new Serial(this, portName, 115200);
  mSerialport.clear();
  mSerialport.bufferUntil(endflag); //generate serial event when endflag is received

  background(0);
  smooth();
  //graph setup
  r1  = new RollingLine2DTrace(new eq1(),250,0.1f);
  r1.setTraceColour(255, 0, 0);
  g = new Graph2D(this, 1080, 500, false);
  g.setYAxisMax(10000);
  g.addTrace(r1);
  g.position.y = 50;
  g.position.x = 100;
  g.setYAxisTickSpacing(500);
  g.setXAxisMax(10f);
}

void draw () {
  background(200);
  //g.draw(); enable this and program crashes quickly
}

void serialEvent (Serial mSerialport) 
{
  byte[] inBuffer = new byte[200];
  mSerialport.readBytesUntil(seperator, inBuffer);
  String inString = new String(inBuffer);
  String subString = "";
  int startFlag = inString.indexOf("A");
  int endFlag = inString.indexOf("Z");
  if (startFlag == 0 && endFlag == 48)
  {
    subString = inString.substring(startFlag+1,endFlag);
  }
  else 
  {
    println("ERROR: BAD MESSAGE DISCARDED!");
    subString = "";
  }

  if ( subString.length() == 47) 
  {
    svalues = (splitTokens(subString)); 
    values = int(splitTokens(subString)); 
    println(svalues);

    //   if (db.connect()) //enable this and program crashes quickly
    //    {
    //      if ( svalues[0] != null && svalues[7] != null) 
    //      {
    //      statement = svalues[7] + ", " + svalues[0] + ", " + svalues[1] + ", " + svalues[2] + ", " + svalues[3] + ", " + svalues[4] + ", " + svalues[5] + ", " + svalues[6];
    //      db.execute( "INSERT INTO rawdata (messageid,press1,press2,press3,press4,light1,light2,io1) VALUES (" + statement + ");" );
    //      }
    //   }
  }
}

While I'm not familiar with your specific platform, my first thought from reading your problem description is that you still have a timing problem. At 115,200bps, data is coming in rather quickly-- more than 10 characters every millisecond. As such, if you spend precious time opening a database (slow file IO) or drawing graphics (also potentially slow), you might well not be able to keep up with the data.

As such, it might be a good idea to put the serial port processing on its own thread, interrupt, etc. That might make the multitasking much easier. Again, this is just an educated guess.

Also, you say that your program "crashes" when you enable the other operations. Do you mean that the entire process actually crashes, or that you get corrupted data, or both? Is it possible that you are overrunning your 200 byte inBuffer[]? At 115kbps, it wouldn't take but 20ms to do so.