Arduino, DS18B20, Ethernet Shield, Pachube.Com

Update 2: The sensor is now outside, and running on parasitic power.

Update: The data is now available in a more mobile-friendly web page here.

Arduino code, based on (i.e. copypasted & modified a little) stuff from http://www.dial911anddie.com/weblog/2009/12/arduino-ethershield-1wire-temperature-sensor-pachube/ is below. Requires the 1-wire library and the Dallas Temperature Control library, both of which can be downloaded from here. Original code utilized DHCP, but I found this to be somewhat unstable and went with a static IP address instead.

DS18B20 gets it's power from Arduino, and the data line (that's the center pin) is connected to Arduino pin 8. Data line is pulled up to +5V through a 4k7 resistor, as suggested in Maxim literature. Parasitic power supply was not used as proper voltage was readily available from Arduino. Please note that even though parasitic power is not used, the pull-up resistor is still necessary (see the data sheet).

#include <Ethernet.h>
#include <OneWire.h>
#include <DallasTemperature.h>

char PACHUBE_API_STRING[] = "";  // Your API key
int PACHUBE_FEED_ID = 0; // Your feed ID 

// Digital IO port used for one wire interface
int ONE_WIRE_BUS = 8 ;

// Ethernet mac address - this needs to be unique
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

// IP addres of www.pachube.com
byte server[] = { 209,40,205,190 };

// Arduino address
byte ip[] = { 10, 0, 0, 223 };
byte gateway[] = { 10, 0, 0, 2 };

char version[] = "PachubeClient Ver 0.01c";

#define CRLF "\r\n"

// simple web client to connect to Pachube.com 
Client client(server, 80);

// Setup a oneWire instance to communicate with any OneWire device
OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature. 
DallasTemperature sensors(&oneWire);

// 1wire device address
DeviceAddress thermometer;

void setup()
{
   // Note: Ethernet shield uses digitial IO pins 10,11,12, and 13   
   Serial.begin(9600);
  
   Serial.println(version);
   Serial.println();
  
   // locate devices on the 1Wire bus
   Serial.print("Locating devices on 1Wire bus...");
   sensors.begin();
   int count = sensors.getDeviceCount();
   Serial.print("Found ");
   Serial.print( count );
   Serial.println(" devices on 1wire bus");

   // select the first sensor   
   for ( int i=0; i<count; i++ )
   {
      if ( sensors.getAddress(thermometer, i) ) 
      {
         Serial.print("1wire device ");
         Serial.print(i);
         Serial.print(" has address: ");
         printAddress(thermometer);
         Serial.println();
      }
      else
      {
         Serial.print("Unable to find address for 1wire device "); 
         Serial.println( i );
      }  
   }
  
   // show the addresses we found on the bus
   Serial.print("Using 1wire device: ");
   printAddress(thermometer);
   Serial.println();

   // set the resolution to 9 bit 
   sensors.setResolution(thermometer, 9);

   Serial.print("Initializing ethernet...");  
   delay(5000);
   Ethernet.begin(mac, ip, gateway);
   delay(5000);
   Serial.println(" done.");
}

void sendData()
{     
   float temp = sensors.getTempC(thermometer);
   //float temp = sensors.getTempF(thermometer);
   Serial.print("Temp=");
   Serial.println(temp);
  
   Serial.println("connecting...");

   if (client.connect()) 
   {
      Serial.println("connected");
      
      client.print(
         "PUT /api/feeds/" );
      client.print(PACHUBE_FEED_ID);
      client.print(".csv HTTP/1.1" CRLF
                   "User-Agent: Fluffy Arduino Ver 0.01" CRLF
                   "Host: www.pachube.com" CRLF 
                   "Accept: */" "*" CRLF  // need to fix this 
                   "X-PachubeApiKey: " );
      client.print(PACHUBE_API_STRING);
      client.print( CRLF 
                    "Content-Length: 5" CRLF
                    "Content-Type: application/x-www-form-urlencoded" CRLF
                    CRLF );
      client.println(temp);
      unsigned long reqTime = millis();
      
      // wait for a response and disconnect 
      while ( millis() < reqTime + 10000) // wait 10 seconds for response  
      {
         if (client.available()) 
         {
            char c = client.read();
            Serial.print(c);
         }

         if (!client.connected()) 
         {
            Serial.println();
            Serial.println("server disconnected");
            break;
         }
      }
      
      Serial.println("client disconnecting");
      Serial.println("");
      client.stop();
   } 
   else 
   {
      Serial.println("connection failed");
   }
}

void printAddress(DeviceAddress deviceAddress)
{
   for (uint8_t i = 0; i < 8; i++)
   {
      if (deviceAddress[i] < 16) Serial.print("0");
      Serial.print(deviceAddress[i], HEX);
   }
}

void loop()
{
   sensors.requestTemperatures(); // Send the command to get temperatures
   sendData();
   delay( ( 5l * 60l * 1000l) - 11000l  ); // wait 5 minutes
}