ridiculously long delay on Processing and Arduino serial communication

jimbbq

ridiculously long delay on Processing and Arduino serial communication

in Integration and Hardware • 1 month ago

dear all

I am trying to make a very simple program using a potentiometer to adjust the background colour of Processing output window.

I write the potentiometer value into the serial port, and the processing code reads the information from the serial port. The problem I am facing is there is a ridiculously long delay of Processing reading the information from serial port!

I am using a mac.

Does anyone have this problem? Is there a solution?

[edit: when I said ridiculous, i did mean sometimes up to 1 minutes!!]

thanks for your help

jim

Replies(4)

paulr451

Re: ridiculously long delay on Processing and Arduino serial communication

1 month ago

Hi Jim,

I talk to my Arduino from Processing all the time and do not have this problem - on Windows. I suggest opening a terminal on the com port and check to see if the problem is with the Arduino or the Mac. I know Processing uses the RXTX-2 library, which I use in other Java projects outside Processing, perhaps there is a problem with it on the Mac.

Anyway, isolate the problem with a terminal session, and go from there. Anyone on a Mac seen this problm?

Paul

jimbbq

Re: ridiculously long delay on Processing and Arduino serial communication

1 month ago

Hi Paul

thanks for your reply. I tried it on my windows machine... the same problem happened....!

Let me copy and paste my codes here. It is really very simple:

// Arduino Code

/ /--------------------------

void setup() {

// initialize serial communication

Serial.begin(9600);

}

void loop() {

// read the value of A0, divide by 4 and

// send it as a byte over the serial connection

Serial.write(analogRead(A0)/4) ;

delay(1);

}

// Processing code

//--------------------------------------------------------------------

// import the serial library

import processing.serial.*;

// create an instance of the serial library

Serial myPort;

// create an instance of PImage

PImage logo;

// a variable to hold the background color

int bgcolor = 0;

void setup() {

// set the color mode to Hue/Saturation/Brightness

colorMode(HSB, 255);

// load the Arduino logo into the PImage instance

logo = loadImage(" http://arduino.cc/ en/pub/skins/arduinoWide/img/ logo.png");

// make the window the same size as the image

size(logo.width, logo.height);

// print a list of available serial ports to the

// Processing staus window

println("Available serial ports:");

println(Serial.list());

// Tell the serial object the information it needs to communicate

// with the Arduno. Change Serial.list()[0] to the correct

// port corresponding to your Arduino board. The last

// parameter (e.g. 9600) is the speed of the communication. It

// has to correspond to the value passed to Serial.begin() in your

// Arduino sketch.

myPort = new Serial(this, Serial.list()[0], 9600);

// If you know the name of the port used by the Arduino board, you

// can specify it directly like this.

// port = new Serial(this, "COM1", 9600);

}

void draw() {

// if there is information in the serial port

if ( myPort.available() > 0) {

// read the value and store it in a variable

bgcolor = myPort.read();

// print the value to the status window

println(bgcolor);

}

// Draw the background. the variable bgcolor

// contains the Hue, determined by the value

// from the serial port

background(bgcolor, 255, 255);

// draw the Arduino logo

image(logo, 0, 0);

}

paulr451

Re: ridiculously long delay on Processing and Arduino serial communication

1 month ago

I see the problem, I was able to reproduce it. You are sending data too fast. Processing loop is at 60 per sec, but you are sendind data at 1000 per sec. The serial buffer is full of old data. Change arduino code to delay(100) or more and it will work better. What you really want is for processing to ask arduino for data, then get response. Sorry, I don't have time to post example right now, I have a program that does this nicely. I dig it up and post when I can.

jimbbq

Re: ridiculously long delay on Processing and Arduino serial communication

1 month ago

thanks! You are a star!

It works now. I wasn't aware of this speed thing. Another solution to this was to use myPort.clear() to clear the serial buffer at the end of the Processing loop I guess.

Thanks a lot for your help :)

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