Experiencing lots of lag

[skrrt.exe]

I just started using Processing today and kind of just jumped right into it. I used it a lot on Khan Academy but never with an Arduino. I have a book that taught me a little bit about how to use processing and using it with an Arduino. All of my code works properly except for the enormous amount of lag. I have a joystick and a button that controls a rectangle in the canvas. When I move the joystick, it should instantly move the rectangle accordingly. I wait for a minimum of 40 seconds and the longer my code runs the more lag I experience. Is this something to do with my laptop or Processing? How do I fix it?
Arduino code:

int stickX, stickY, stickBtnState, btnState, stickBtnPin = 4, btnPin = 2, stickXPin = 0, stickYPin = 1;

void setup() {
  Serial.begin(9600);
  pinMode(btnPin, INPUT);
  pinMode(stickBtnPin, INPUT);
}

void loop() {
  stickX = analogRead(0) / 4;
  stickY = analogRead(1)  / 4;
  stickBtnState = digitalRead(stickBtnPin);
  btnState = digitalRead(btnPin);
  Serial.print("X:");
  Serial.println(stickX);
  Serial.print("Y:");
  Serial.println(stickY);
  Serial.print("sBtn:");
  Serial.println(stickBtnState);
  Serial.print("btn:");
  Serial.println(btnState);
  delay(3);
}

Processing code:

import processing.serial.*;

Serial port;

int x = 10, y = 10;
float stickX, stickY, stickBtn, btn, colour = 0;
String readSerial;

void setup() {
  size(400, 400);
  port = new Serial(this, Serial.list()[0], 9600);
}

void draw() {
  background(255);
  fill(colour);
  rect(x, y, 10, 10);
  serialEvent();
}

void serialEvent() {
  String inString = port.readStringUntil('\n');
  if (inString != null) {
    if (inString.indexOf('X') == 0) {
      inString = inString.substring(2);
      stickX = float(inString);
      println(stickX);
      if (stickX > 135) {
        x++;
      } else if (stickX < 125) {
        x--;
      }
    } else if (inString.indexOf('Y') == 0) {
      inString = inString.substring(2);
      stickY = float(inString);
      if (stickY > 135) {
        y++;
      } else if (stickY < 125) {
        y--;
      }
    } else if (inString.indexOf('s') == 0) {
      inString = inString.substring(5);
      stickBtn = float(inString);
      if (stickBtn == 1) {
        colour = 100;
      }
    } else if (inString.indexOf('b') == 0) {
      inString = inString.substring(4);
      btn = float(inString);
      if (stickBtn == 1) {
        colour = 255;
      }
    }
  }
}

Any help is greatly appreciated by me. Thanks!

[kll]

please take a look here
https://processing.org/reference/libraries/serial/serialEvent_.html
do you notice that there the

serialEvent(Serial p)

is NOT called from draw()!

---

sending a line from arduino with a delay of 3 milli seconds means you try
to get >300 lines per second??
but use a serial transport of 9600bd
that does not fit.
start with a delay(1000) ( one line per second ) and change later down to optimize.

---

anyhow,
how you know what is received by processing ( if anything at all )
after

 if (inString != null) {
// use a 
  println(inString);

( and possibly post the console print here )

---

after all that runs well,
you can start with the real work,
analyze the string you send to get back NUMBERS out of it

[skrrt.exe]

Thanks! I didn’t know that I had to add Serial p inside the parameters of serialEvent(). The book did not show this… The code was not working without me calling serialEvent inside of draw()
Also, I do print numbers with Serial.println()… What are you asking in the second part? The code works without me increasing the delay. The code prints X:(num) or Y:(num) where num is 0 - 255 and 0 or 1 for the buttons. After that, I use substring() to remove X: or Y: and others… So I do get numbers out of it. The part before the colon is just so that the code can figure out what each number is for.

[kll]

good you get good lines and good numbers out of it,
and what was the question? LAG

means ? you get one line in 40 sec instead 300 line per sec?
OR
you mean that a button ( arduino pin state change ) not come though?

[skrrt.exe]

There is no more lag, everything works now. Thanks

[GoToLoop]

Using two different readStringUntil "characters"

Now that it seems all’s been sorted out, how about some optimization? The range [-10 to 10] is so small (5-bit) that it comfortably fits in a byte (8-bit). So, rather than send those 2 small values as TSV, w/ lotsa extra separator characters, we can simply send 2 bytes only using Serial.write(): https://www.Arduino.cc/reference/en/language/functions/communication/serial/write/ We just need to create a char array of length = 2: signed char xy[2]; #define BAUDS 115200 #define DELAY 10 #define…

[skrrt.exe]

Serial.write() doesn’t end with a new line… I need for it to end with a new line to read the button states

[GoToLoop]

Using two different readStringUntil "characters"

Well, I don’t have any Arduino hardware and neither even seen 1 in front of me yet! So I can only do blind coding in the dark for you. Theoretically, an Arduino C code like this 1: void setup() { Serial.begin(115200); } void loop() { const int x = map(analogRead(A1), 0, 1023, -10, 10); const int y = map(analogRead(A0), 0, 1023, -10, 10); Serial.print(x); // "-5" Serial.write('\t'); // '\t' Serial.println(y); // "10" + "\r\n" delay…

[skrrt.exe]

I think I’m okay with my current code. Thank you though!