Temperature recorder with Arduino/Java/R

ArduinoTemperatureSketch.ino

/* Original code from the Arduino Experimentation Kit Example Code             |
 * CIRC-10 .: Temperature :. (TMP36 Temperature Sensor) |
 * Amended to be used in Java/R
 */

//TMP36 Pin Variables
int temperaturePin = 0;

void setup()
{
  Serial.begin(9600);
}
 
void loop()                     // run over and over again
{
 float temperature = getVoltage(temperaturePin);  //getting the voltage reading from the temperature sensor
 temperature = (temperature - .5) * 100;          //converting from 10 mv per degree wit 500 mV offset
                                                  //to degrees ((volatge - 500mV) times 100)
 Serial.print("T");
 Serial.println(temperature);                     //printing the result
 delay(1000);                                     //waiting a second
}

float getVoltage(int pin){
 return (analogRead(pin) * .004882814); //converting from a 0 to 1023 digital range
                                        // to 0 to 5 volts (each 1 reading equals ~ 5 millivolts
}

SerialTemperature.java

import java.io.InputStream;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.util.Enumeration;

public class SerialTemperature implements SerialPortEventListener {

    SerialPort serialPort;
    /** The port we're normally going to use. */
    private static final String PORT_NAMES[] = {
        "/dev/ttyS32", // Linux
    };
    /** Buffered input stream from the port */
    private InputStream input;

    /** Milliseconds to block while waiting for port open */
    private static final int TIME_OUT = 2000;
    /** Default bits per second for COM port. */
    private static final int DATA_RATE = 9600;

    private String temperatureBuffer;

    public void initialize() {
        CommPortIdentifier portId = null;
        Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

        // iterate through, looking for the port
        while (portEnum.hasMoreElements()) {
            CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
            for (String portName : PORT_NAMES) {
                if (currPortId.getName().equals(portName)) {
                    portId = currPortId;
                    break;
                }
            }
        }

        if (portId == null) {
            System.out.println("Could not find COM port.");
            return;
        }

        try {
            // open serial port, and use class name for the appName.
            serialPort = (SerialPort) portId.open(this.getClass().getName(),
                                                  TIME_OUT);

            // set port parameters
            serialPort.setSerialPortParams(DATA_RATE,
                                           SerialPort.DATABITS_8,
                                           SerialPort.STOPBITS_1,
                                           SerialPort.PARITY_NONE);

            // open the streams                                                                                                                 
            input = serialPort.getInputStream();

            // add event listeners
            serialPort.addEventListener(this);
            serialPort.notifyOnDataAvailable(true);
        } catch (Exception e) {
            System.err.println(e.toString());
        }
    }


    /**
     * This should be called when you stop using the port.
     * This will prevent port locking on platforms like Linux.
     */
    public synchronized void close() {
        if (serialPort != null) {
            serialPort.removeEventListener();
            serialPort.close();
        }
    }

    /**
     * This will be used by R to retrieve the temperature value
     */
    public synchronized Float read() {
        return Float.valueOf(temperatureBuffer.substring(1)).floatValue();
    }

    /**                                                                                                                                         
     * Handle an event on the serial port. Read the data and save it to the buffer                                                              
     */
    public synchronized void serialEvent(SerialPortEvent oEvent) {
        if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            try {
                int available = input.available();
                byte chunk[] = new byte[available];
                input.read(chunk, 0, available);

                String s = new String(chunk);
                if(s.contains("T")) {
                    temperatureBuffer = s;
                } else {
                    temperatureBuffer += s;
                }

            } catch (Exception e) {
                System.err.println(e.toString());
            }
        }
    }

}

TemperatureRecorder.R

setwd('/data/R/ArduinoTemp/')
require(rJava)
require(ggplot2)

.jinit(classpath='SerialTemperature.jar')
ardJava <- .jnew('SerialTemperature')

.jcall(ardJava, returnSig='V', method='initialize')

tempCapture <- NULL
while(Sys.Date()<'2012-11-11') {
  system('sleep 30')
  try({
    ans <- .jsimplify(.jcall(ardJava, returnSig='Ljava/lang/Float;', method='read'))
    tempCapture <- rbind(tempCapture, data.frame(Time=Sys.time(), Temperature=ans))
    print(ggplot(tempCapture) + geom_line(aes(x=Time, y=Temperature)) + theme_bw())
  }, silent=T)
}                                

.jcall(ardJava, returnSig='V', method='close')