How to work around "Error, disabling serialEvent()"?

Oppogo

Hello! I recently got my own Arduino and decided to use it to make a pulse sensor from a tutorial. The tutorial also suggested using Processing to display peaks of pulse. I used their code but after returning few values and a peak of the graph the process stops, encountering a null value and giving the "disabling serialEvent() for COM3" error. Does anyone know how to deal with this error? I would love to learn more about it!

The code looks like this:

// Based on examples from Arduino's Graphing Tutorial and OscP5 documentation import processing.serial.*; Serial myPort; // The serial port int xPos = 1; // horizontal position of the graph float oldHeartrateHeight = 0; // for storing the previous reading

void setup () {
// set the window size:
size(600, 400);
frameRate(25);

// List available serial ports.
println(Serial.list());

// Setup which serial port to use.
// This line might change for different computers.
myPort = new Serial(this, Serial.list()[1], 9600);

// set inital background:
background(0);
}

void draw () {
}

void serialEvent (Serial myPort) {
// read the string from the serial port.
String inString = myPort.readStringUntil('\n');

if (inString != null) {
// trim off any whitespace:
inString = trim(inString);
// convert to an int
println(inString);
int currentHeartrate = int(inString);

// draw the Heartrate BPM Graph.
float heartrateHeight = map(currentHeartrate, 0, 1023, 0, height);
stroke(0,255,0);
line(xPos - 1, height - oldHeartrateHeight, xPos, height - heartrateHeight);
oldHeartrateHeight = heartrateHeight;
// at the edge of the screen, go back to the beginning:
if (xPos >= width) {
xPos = 0;
background(0);
} else {
// increment the horizontal position:
xPos++;

}
}
}

GoToLoop

https://forum.Processing.org/two/discussion/15473/readme-how-to-format-code-and-text

Do not modify sketch's canvas outside the "Animation" Thread! :-@
Event functions aren't the place to draw() anything! [-X

jeremydouglass

...so, you could follow GoToLoop's advice by:

1. in your event function by setting a flag, loading a variable, or queuing something on a stack, then
2. drawing according to that event data during the next draw() loop, either in draw() directly by having draw call a custom function during its loop e.g. drawEvents() and drawing there.

benja

They should really change their tutorial...

Here is one of the other threads with the same problem: https://forum.processing.org/two/discussion/comment/57867/