How to display several curves using Arduino and a DHT11 sensor ?

BigMacTheory

Hi,

I am a newbie using Processing and I would like to know how to draw several curves in one graph. It should not be too complicated, but the main thing is that I am using Arduino and a DHT11 sensor which monitors humidity and temperature with one digital output. What I would like to achieve is to monitor the values of humidity and temperature on Processing in one graph.

Here is the Arduino program :

#include "DHT.h"
#define DHTPIN 2     // what pin we're connected to
#define DHTTYPE DHT11  

// Initialize DHT sensor for normal 16mhz Arduino
DHT dht(DHTPIN, DHTTYPE);

void setup() {

  Serial.begin(9600); 
  dht.begin();
 }

void loop() {

  int h = dht.readHumidity();
  // Read temperature as Celsius
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit
  float f = dht.readTemperature(true);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
    }

  // Compute heat index
  // Must send in temp in Fahrenheit!
  float hi = dht.computeHeatIndex(f, h);

  //Serial.print("Humidity: "); 
  Serial.println(h);
  //Serial.print("Temperature: "); 
  Serial.print(t);
  delay(500);                        // wait 100ms for next reading


  }

And here is the Processing program I found on the Internet :

import processing.serial.*;

Serial myPort;        // The serial port
int xPos = 1;         // horizontal position of the graph 

//Variables to draw a continuous line.
int lastxPos=1;
int lastheight=0;
float val;

void setup () {
  // set the window size:
  size(800, 600);        

  // List all the available serial ports
  println(Serial.list());
  // Check the listed serial ports in your machine
  // and use the correct index number in Serial.list()[].

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

  // A serialEvent() is generated when a newline character is received :
  //myPort.bufferUntil('\n');
  background(0);      // set inital background:
}
void draw () {
  if ( myPort.available() > 0) {  // If data is available,
    val = myPort.read();          // read it and store it in val
    // Convert the values to set the radius

  }
  // everything happens in the serialEvent()
}

void serialEvent (Serial myPort) {
  // get the ASCII string:
  String inString = myPort.readStringUntil('\n');
  if (inString != null) {
    inString = trim(inString);                // trim off whitespaces.
    float inByte = float(inString);           // convert to a number.
    inByte = map(inByte, 0, 100, 0, height); //map to the screen height.

    //Drawing a line from Last inByte to the new one.
    stroke(127,34,255);     //stroke color
    strokeWeight(2);        //stroke wider
    line(lastxPos, lastheight, xPos, height - inByte); 
    lastxPos= xPos;
    lastheight= int(height-inByte);

    // at the edge of the window, go back to the beginning:
    if (xPos >= width) {
      xPos = 0;
      lastxPos= 0;
      background(0);  //Clear the screen.
    } 
    else {
      // increment the horizontal position:
      xPos++;
    }
  }
}

I have the feeling it should be somewhere near this line String inString = myPort.readStringUntil('\n'); but I have no idea how to extract both the temperature and moisture ; it does work with the temperature or the humidity depending on which but I don't know how to do with both.

Could you help me ?

Thanks,

camperos

for send multiple values, search the arduino-processing example "virtualcolormixer", and modify your arduino-processing example "graph"

BigMacTheory

The problem here is that humidity and temperature come from the same digital output... I don't know how to "separate" those data.

Ater

In the suggested example they use comma to separate values:

Serial.print(h);
Serial.print(",");
Serial.println(t);

Then, this may be separated from the processing side with the use of split:

float[] vals = float(split(inString, ","));

You will have then vals[0] == h; and vals[1] == t;