Hi there...

I am learning to get Processing to talk to an Arduino board over the serial connection. However, I have some problems with the data coming in. This data is in the form of an ASCII string from 0 to 1024 followed by a carriage return.

Basically, I am perfectly able to get the incoming data to show up when I treat it as a string. However, when I try to convert the string to an integer so that I can do something useful with it, all I get is a long chain of zeroes.

Here's the code I'm using right now...what could the problem be?
Code:

import processing.serial.*;

Serial port;			 
int datapoint = 0;

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

void draw () {
  
  while (port.available() > 0) {
    String n = port.readString();
    if (n != null) {
     int datapoint = int(n);
	println(datapoint);
	
	 }
    
  }
}
 

Basically this code gives me a chain of zeroes. If I swap println(datapoint); for println(n); it will give me the data but not in a form I can use.

Thanks,
CUID

Here's what is coming over the Arduino serial monitor:
Code:

804

847

850

852

855

852

850

843

835

831
 

And here's another sample of what I get in the console of the processing IDE  with println(n) (different data coming in, but this is an example of the formatting)

Code:

100

99

99

98

97

96

95
 

Seems exactly the same. Interesting that there is a space between the data points when I paste it here -- I'm starting to think it's a formatting thing. Do I need to strip carriage returns or something?

Thanks! That was extremely useful. It seems that there's a synchronization problem between the rate the arduino is outputting data and the rate that the program is reading it.

First, I reprogrammed the arduino to output comma-terminated data instead of CR-terminated, since it's easier to see. result is the arduino gives me data like the following:

Code:

846,821,799,779,770,756,749,741,730,727,723,717,714,712,714,711,712,717,719,721,728,731,736,741,742,748,753,755,759,764,766,771,774,781,783,784,
788,787,787,789,788,787,786,780,779,778,776,775,774,776,775,774,773,774,775,776,781,786,786,724,666,607,548,490,430,370,306,242,186,186,186,187,188 

using println("value##"+n+"##"); on that incoming data gives the following:

Code:

value##9,9,9,9,10,10,10,10,10,##
value##10,8,8,##
value##8,8,8,7,7,##
value##7,7,7,7,7,7,##
value##7,7,8,7,7,7,7,7,7,7,##
value##8,8,8,9,8,##
value##8,8,9,9,##
value##9,8,9,9,9,9,##
value##9,9,8,8,8,8,7,7,##
value##7,7,8,##
value##8,##
 

So yeah, the problem is definitely a synch error. :p
I'm going to try taking the string data and splitting it at the commas and putting it in an array instead. For the record, any idea what I might do to get these synched properly? I have a 20-msec delay between updates on the arduino, so a 50hz sampling rate; I set the framerate of the Processing code to 50  as well, but it doesn't help.

Thanks again.