Arduino - Processing and serial communication

Question

I need to get a serial signal from the Arduino board into a Processing sketch. I am sending values in string format, like "R12" "S40" "T80". When I capture those strings from Processing it will printing vertically (new line for each character). How can I get this as a string as it is what we sent?

I need code that can be put inside Processing's serialEvent method.

Arduino code

void loop() {
  int r = random(10, 100);
  int s = random(10, 100);
  int t = random(10, 100);
  Serial.print("R" + String(r));
  Serial.print("S" + String(s));
  Serial.print("T" + String(t));
  delay(1000);
}

Processing Code

String data = "";
int R, S, T;
void serialEvent(Serial p) {
  while(p.available() > 0) {
    data = p.readString();
  }
  println(data);
}

I need to get the last received R S T values, respectively, to the R S T variables.

Answer 1

As mentioned previously, it is better to get the all the code to find the problem.

I suppose you did not add the function "bufferUntil()" in the Processing setup, so each time the serial received a value, it just displays it. I can propose you a solution. It is not the only one, but it seems to work.

In your Arduino code, instead of the Serial.print(), you should use Serial.println() to delimit your message.

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

void loop() {
    int r = random(10, 100);
    int s = random(10, 100);
    int t = random(10, 100);
    Serial.println("R" + String(r));
    Serial.println("S" + String(s));
    Serial.println("T" + String(t));
    delay(1000);
}

So you will send the message as

Rxx
Sxx
Txx

In Processing, you have to use the function "bufferUntil(lf)". It will save all messages from the serial port until it receives a "/n". After that, you should use another function to associate your identifier with the value.

// Example by Tom Igoe
import processing.serial.*;
Serial myPort;    // The serial port
PFont myFont;     // The display font
String inString;  // Input string from serial port
int lf = 10;      // ASCII linefeed

String data = "";
int R, S, T;

void setup() {
  size(400, 200);
  // List all the available serial ports:
  printArray(Serial.list());
  // Open whatever port is the one you're using, mine is one.
  myPort = new Serial(this, Serial.list()[1], 9600);
  myPort.bufferUntil(lf); // Delimiter of serial buffer end line
}

void draw() {
  background(0);
  text("received: " + " R=" + R + "  S=" + S + "  T=" + T, 10, 50); // Display value on the window
}

void serialEvent(Serial p) {
  while(p.available() > 0) {
    String buf = p.readString();   // Read serial input
    println(buf);
    if(!buf.equals('\n'))    // Delete null='/n' from arduino println()
      data = buf;            // Save buffer
  }

  /*
      char id = data.charAt(0);                    // Get id from buffer
      int value = parseInt(data.substring(1, 3));  // Get the value from buffer
      identifyVariable(id, value);                 // Associate id and value
  */
}

void identifyVariable(char ID, int value) {
  switch(ID) {            // Associate id with value
    case('R'):
      R = value;
      break;
    case('S'):
      S = value;
      break;
    case('T'):
      T = value;
      break;
    default:
      println("error " + ID + " " + value);
      break;
  }
}