public void processSerialData() {
    byte[] inBuf = new byte[20];
    switch (serial.read()) {
      case 'A':
        // wait for all data arrived
        while (serial.available() < 16) {}
        // read all data
        serial.readBytes(inBuf);
        Acc_RAW = (inBuf[1] << 8) + (inBuf[0] & 0xFF);
        Gyro_RAW = (inBuf[3] << 8) + (inBuf[2] & 0xFF);
        // int intbit = 0;
        // intbit = (inBuf[7] << 24) | ((inBuf[6] & 0xFF) << 16) | ((inBuf[5] & 0xFF) << 8) |
        // (inBuf[4] & 0xFF);
        // Angle = Float.intBitsToFloat(intbit);
        int AngleInt = (inBuf[5] << 8) + (inBuf[4] & 0xFF);
        Angle = PApplet.parseFloat(AngleInt) / 10;
        Acc_Angle = (inBuf[7] << 8) + (inBuf[6] & 0xFF);
        Gyro_Rate = (inBuf[9] << 8) + (inBuf[8] & 0xff);
        Drive = (inBuf[11] << 8) + (inBuf[10] & 0xFF);
        statusFlag = (inBuf[13] << 8) + (inBuf[12] & 0xFF);
        int BatLevelInt = (inBuf[15] << 8) + (inBuf[14] & 0xFF);
        Steer = (inBuf[17] << 8) + (inBuf[16] & 0xFF);
        BatLevel = PApplet.parseFloat(BatLevelInt) / 10;
        println(
            "Acc="
                + Acc_RAW
                + "  Gyro="
                + Gyro_RAW
                + "  Angle="
                + Angle
                + "  Acc_Angle="
                + Acc_Angle
                + "  Gyro_Rate="
                + Gyro_Rate
                + "  Drive="
                + Drive
                + "  Status="
                + statusFlag);
        break;

      case 'E':
        // wait for all data arrived
        while (serial.available() < 6) {}
        // read all data
        serial.readBytes(inBuf);
        int P = (inBuf[1] << 8) + (inBuf[0] & 0xFF);
        int I = (inBuf[3] << 8) + (inBuf[2] & 0xFF);
        int D = (inBuf[5] << 8) + (inBuf[4] & 0xFF);
        conf_KP.setValue(P);
        conf_KI.setValue(I);
        conf_KD.setValue(D);
        println("P=" + P + " I=" + I + " D=" + D);
        break;
    }
    serial.clear();
  }
  public void draw() {
    background(0);
    // Strings composition
    textFont(createFont("Arial bold", 24));
    fill(c_red);
    stroke(255);
    text("OpenWheels GUI V1.0", 20, 30);
    textSize(16);
    // textAlign(CENTER);
    fill(c_azure);
    text("Acc_RAW:  " + Acc_RAW, 150, 65);
    AccSlider.setValue(Acc_RAW);
    text("Gyro_RAW: " + Gyro_RAW, 150, 90);
    GyroSlider.setValue(Gyro_RAW);
    text("Acc_Angle:  " + Acc_Angle + "\u00b0", 150, 115);
    text("Gyro_Rate: " + Gyro_Rate + "\u00b0/sec", 150, 140);
    text("Drive: " + Drive, 150, 165);
    text("Steer: " + Steer, 150, 190);
    text("BatLevel: " + nf(BatLevel, 1, 1) + "V", 150, 215);
    text("Status: " + statusFlag, 150, 240);
    graphGauge();
    graphGrid();

    // call the function that plot the angular of acc, with few screen settings
    graphRoll(PApplet.parseFloat(Acc_Angle), VideoBuffer2, c_red); // xPos, YPos, YSpan
    // call the function that plot the estimate angular, with few screen settings
    graphRoll(Angle, VideoBuffer1, c_yellow); // xPos, YPos, YSpan

    // call arduino for data every timePolling [msec]
    int timePolling = 50; // 50msec=20Hz
    time1 = millis();
    if (init_com == 1) {
      while (serial.available() > 0) processSerialData();
      if ((time1 - time2) > timePolling) {
        if (requestPID == true) {
          serial.write('E');
          requestPID = false;
        } else if (writePID == true) {
          int P = PApplet.parseInt(conf_KP.value());
          int I = PApplet.parseInt(conf_KI.value());
          int D = PApplet.parseInt(conf_KD.value());
          char data[] = {0, 0, 0, 0, 0};
          data[0] = 'W';
          data[1] = PApplet.parseChar(P);
          data[2] = PApplet.parseChar(I);
          data[3] = PApplet.parseChar(D);
          data[4] = ' ';
          String str = new String(data);
          serial.write(str);
          println(str);
          // println(" P=" + P + " I=" + I + " D=" + D);
          writePID = false;
        }
        // else if (RUN==true ) {serial.write('A');}
        else {
          serial.write('A');
        }
        time2 = time1;
      }
    }
  }
  public int[] getPacket() {
    boolean gotAPacket = false; // whether the first byte was 0x7E
    int packetLength = -1; // length of the dataArray
    int[] thisdataArray = null; // the dataArray to return
    int checksum = -1; // the checksum as received
    int localChecksum = -1; // the chacksum as we calculate it

    // read bytes until you get a 0x7E
    port.clear(); // flush the buffer so that no old data comes in

    while (port.available() < 1) {; // do nothing while we wait for the buffer to fill
    }

    // this is a good header. Get ready to read a packet
    if (port.read() == 0x7E) {
      gotAPacket = true;
    }

    // if the header byte is good, try the rest:
    if (gotAPacket) {
      // read two bytes
      while (port.available() < 2) {; // wait until you get two bytes of length
      }
      int lengthMSB = port.read(); // high byte for length of packet
      int lengthLSB = port.read(); // low byte for length of packet

      // convert to length value
      packetLength = (lengthLSB + (lengthMSB << 8));
      // sanity check: if the packet is too long, bail.
      if (packetLength > 200) {
        System.out.println("Length (" + packetLength + ") too long, discarding packet.");
        return null;
      }

      if (DEBUG) System.out.print("> [" + packetLength + "]: ");

      // read bytes until you've reached the length
      while (port.available() < packetLength) {; // do nothing while we wait for the buffer to fill
      }
      // make an array to hold the data frame:
      thisdataArray = new int[packetLength];

      // read all the bytes except the last one into the dataArray array:
      for (int thisByte = 0; thisByte < packetLength; thisByte++) {
        thisdataArray[thisByte] = port.read();
        if (DEBUG) System.out.print(parent.hex(thisdataArray[thisByte], 2) + " ");
      }

      while (port.available() < 1) {; // do nothing while we wait for the buffer to fill
      }
      // get the checksum:
      checksum = port.read();

      // calculate the checksum of the received dataArray:
      localChecksum = checkSum(thisdataArray);
      // if they're not the same, we have bad data:
      if (localChecksum != checksum) {
        if (DEBUG) System.out.println();
        System.out.print(
            "Bad checksum, discarding packet. Local: " + parent.hex(localChecksum % 256));
        System.out.println(", Remote: " + parent.hex(checksum) + ", Length: " + packetLength);
        // if the checksums don't add up, clear the dataArray array:
        thisdataArray = null;
      }
    }
    // makes a nice printing for debugging:
    if (DEBUG) System.out.println("!");

    // return the data frame.  If it's null, you got a bad packet.
    return thisdataArray;
  }