Incorrect data

skizzo66

I have already created a discussion for this but someone closed it. I created an Arduino sketch where i register the data of a temperature sensor.

This is the sketch:

`

int tmpin = A0;

void setup()
{
 pinMode(tmpin, INPUT);
 Serial.begin(9600);

}

void loop()
{
  //Some calculations to transform the voltage to temperature
  int value = analogRead(A0);
  float voltage = (value / 1024.0) * 5.0;
  float temp = (voltage - 0.5) * 100;


  Serial.println(temp);
  delay(1000);
}  

`

Then i created a Processing script where i represent the Arduino's data. Howewer in the console some values are incorrect, while others are correct.

This is the sketch:

`

import processing.serial.*;

//Serial port
Serial port;

//Value read from serial
float val;

//value to create x and y axes
int x = 150;
int y = 600;

//value to write intervals x and y axes
int x1;
int y1;

void setup()
{
  size(1000, 700);
  background(255);
  //name of the usb port
  String portname = Serial.list()[0];

  //object port
  port = new Serial(this, portname, 9600);

  //Increase in 2 the thickness
  strokeWeight(2);

  //x axis
  line(100, 650, 900, 650);

  //y axis
  line(100, 650, 100, 50);

  //intervals x axis
  for(int i = 0; i < 16;i++)
  {

    line(x, 640, x, 660);
    x = x + 50;

  }  

  //intervals y axis
  for(int i = 0;i < 12; i++)
  {

    line(90, y, 110, y);
    y = y - 50;

  }

  //values x axis
  text("1", 147, 675);
  for(int i = 0;i < 17;i++)
  {



  }  

}

void draw()
{

  //If port is available
  if(port.available() > 0)
  {
    String string = port.readString();
    val = float(string);
    println(val);
  }  

}  

`

colouredmirrorball

We don't have your sensor. Could you post the values you're getting, with an indication of which ones look wrong?

skizzo66

In my Serial monitor i could see values such as 18.5 , 20.2 , 23,7 (degree), while in processing the values sometimes are correct a sometimes incorrect. Ex. 18.5 , 81.9 , Na , ecc.

kfrajer

In your arduino code, you are sending your data with println(). Then in Processing you should get your data using:

String string = port.readStringUntil(ENTER);

I recomend changing the name of your variable string to something different, for example, strVal. Lastly, to avoid null entries, use if(string!=null){...}.

Kf

GoToLoop

https://forum.Processing.org/two/discussion/14534/myport-available-always-0#Item_1

skizzo66

I edited the code adding in the If this lines:

if (strVal != null) {
  println(val);
}

but after 5-6 seconds it raises an exception "Null Pointer Exception"

kfrajer

What line shows the error?

Kf

skizzo66

val = float(strVal);

kfrajer

Ensure strVal in that last line is not null.

if (strVal != null){
  val = float(strVal);
  println(val);
}

Kf

koogs

but don't forget

sometimes incorrect. Ex. 18.5 , 81.9 , Na

so you might need code to handle "Na" too, float() isn't going to work on "Na" (do you mean NaN?)

skizzo66

I solved the problem but there is another one. The datas arrived from arduino are in a range from -10.0 to 40/50.0 degree. How can i transorm they in x coordinates?

skizzo66

This is the new sketch:

`

import processing.serial.*;

//Serial port
Serial port;

//variables read from serial
float val;

//variables to create x and y axes
int x = 150;
int y = 600;

//variables to write line x and y axes
int x1;
int y1;

//variables to write value x axis
int xValue = 147;
int number = 1;

//variable to write value y axis
int yValue = 605;
int number2 = 1;

//variable that rapresent the time
int time = 150;


//Mapped value of temperature

float mapped;



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

void setup()
{
  size(1000, 700);
  background(255);
  //name of the usb port
  String portname = Serial.list()[0];

  //object port
  port = new Serial(this, portname, 9600);

  //Increase in 2 the thickness
  strokeWeight(2);

  //x axis
  line(100, 650, 900, 650);

  //y axis
  line(100, 650, 100, 50);

  //intervals x axis
  for(int i = 0; i < 16;i++)
  {

    line(x, 640, x, 660);
    x = x + 50;

  }  

  //intervals y axis
  for(int i = 0;i < 12; i++)
  {

    line(90, y, 110, y);
    y = y - 50;

  }

  //values x axis
  fill(0); 
  for(int i = 0;i < 16;i++)
  {

     text(str(number), xValue, 675);
     number = number + 1;
     xValue = xValue + 50;

  }  

  //values y axis
  text("1", 65, 605);
  for(int i = 0; i < 12; i++)
  {

     text(str(number2), 65, yValue);
     number2 = number2 + 1;
     yValue = yValue - 50;

  }  

}

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




void draw()
{

  //If port is available
  if(port.available() > 0)
  {
    String strVal = port.readStringUntil(ENTER);


    //to avoid null entries
    if(strVal != null)
    {
    val = float(strVal);  
    mapped = map(val, 50, -30, 650, 0);
    println(val);
    }
  }  


  //Writing of data in the diagram
  strokeWeight(4);
  point(time, mapped);
  time = time + 50;

}  

`

Chrisir

You could look up map() in the reference

you can map values from one range to another range

skizzo66

if you read the code, you can see that i used map but don't work

jeremydouglass

@skizzo66 -- You said:

The datas arrived from arduino are in a range from -10.0 to 40/50.0 degree. How can i transform they in x coordinates?

This is your x-axis:

//x axis
line(100, 650, 900, 650);

So, you've asked how to transform (-10.0 to 50.0) data into (100 to 900) x-values. Your code says map(val, 50, -30, 650, 0) -- but I'm not sure where these numbers are coming from, they don't match your data range and they don't match your x-axis range. That would be:

map(val, -10.0, 50.0, 100, 900);

For more, see the map() reference:

• https://processing.org/reference/map_.html