Pachube sensor client

/*
  Pachube sensor client

 This sketch connects an analog sensor to Pachube (http://www.pachube.com)
 using a Wiznet Ethernet shield. You can use the Arduino Ethernet shield, or
 the Adafruit Ethernet shield, either one will work, as long as it's got
 a Wiznet Ethernet module on board.

 Circuit:
 * Analog sensor attached to analog in 0
 * Ethernet shield attached to pins 10, 11, 12, 13

 created 15 March 2010
 updated 4 Sep 2010
 by Tom Igoe

 http://www.tigoe.net/pcomp/code/category/arduinowiring/873
 This code is in the public domain.

 */

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

int DS18S20_Pin = 9; //DS18S20 Signal pin on digital 9

//Temperature chip i/o
OneWire ds(DS18S20_Pin); // on digital pin 2

// assign a MAC address for the ethernet controller.
// fill in your address here:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
// assign an IP address for the controller:
byte ip[] = {
  192,169,1,20 };
byte gateway[] = {
  192,168,1,1};
byte subnet[] = {
  255, 255, 255, 0 };

//  The address of the server you want to connect to (pachube.com):
byte server[] = {
  209,40,205,190 };

// initialize the library instance:
Client client(server, 80);

long lastConnectionTime = 0;        // last time you connected to the server, in milliseconds
boolean lastConnected = false;      // state of the connection last time through the main loop
const int postingInterval = 10000;  //delay between updates to Pachube.com

void setup() {
  // start the ethernet connection and serial port:
  Ethernet.begin(mac, ip);
  Serial.begin(9600);
  // give the ethernet module time to boot up:
  delay(1000);
}

void loop() {

  float temperature = getTemp();
  Serial.println(temperature);

  // read the analog sensor:
  int sensorReading = temperature;

  // if there's incoming data from the net connection.
  // send it out the serial port.  This is for debugging
  // purposes only:
  if (client.available()) {
    char c = client.read();
    Serial.print(c);
  }

  // if there's no net connection, but there was one last time
  // through the loop, then stop the client:
  if (!client.connected() && lastConnected) {
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
  }

  // if you're not connected, and ten seconds have passed since
  // your last connection, then connect again and send data:
  if(!client.connected() && (millis() - lastConnectionTime > postingInterval)) {
    sendData(sensorReading);
  }
  // store the state of the connection for next time through
  // the loop:
  lastConnected = client.connected();
}

// this method makes a HTTP connection to the server:
void sendData(int thisData) {
  // if there's a successful connection:
  if (client.connect()) {
    Serial.println("connecting...");
    // send the HTTP PUT request.
    // fill in your feed address here:
    client.print("PUT /api/YOUR_FEED_HERE.csv HTTP/1.1\n");
    client.print("Host: www.pachube.com\n");
    // fill in your Pachube API key here:
    client.print("X-PachubeApiKey: YOUR_KEY_HERE\n");
    client.print("Content-Length: ");

    // calculate the length of the sensor reading in bytes:
    int thisLength = getLength(thisData);
    client.println(thisLength, DEC);

    // last pieces of the HTTP PUT request:
    client.print("Content-Type: text/csv\n");
    client.println("Connection: close\n");

    // here's the actual content of the PUT request:
    client.println(thisData, DEC);

    // note the time that the connection was made:
    lastConnectionTime = millis();
  }
  else {
    // if you couldn't make a connection:
    Serial.println("connection failed");
  }

  delay(100);
}


// This method calculates the number of digits in the
// sensor reading.  Since each digit of the ASCII decimal
// representation is a byte, the number of digits equals
// the number of bytes:

int getLength(int someValue) {
  // there's at least one byte:
  int digits = 1;
  // continually divide the value by ten,
  // adding one to the digit count for each
  // time you divide, until you're at 0:
  int dividend = someValue /10;
  while (dividend > 0) {
    dividend = dividend /10;
    digits++;
  }
  // return the number of digits:
  return digits;
}

float getTemp(){
//returns the temperature from one DS18S20 in DEG Celsius

byte data[12];
byte addr[8];

if ( !ds.search(addr)) {
//no more sensors on chain, reset search
   ds.reset_search();
return -1000;
}

if ( OneWire::crc8( addr, 7) != addr[7]) {
Serial.print("CRC is not valid!\n");
return -1000;
}

if ( addr[0] != 0x10 && addr[0] != 0x28) {
Serial.print("Device is not recognized");
return -1000;
}

ds.reset();
ds.select(addr);
ds.write(0x44,1); // start conversion, with parasite power on at the end

byte present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad


for (int i = 0; i < 9; i++) { // we need 9 bytes
  data[i] = ds.read();
}

ds.reset_search();

byte MSB = data[1];
byte LSB = data[0];
float CONT_REMAIN = data[6];
float CONT_PER_C = data[7];

float tempRead = ((MSB << 8) | LSB); //using two's compliment
float TemperatureSum = tempRead/2-0.25+(CONT_PER_C-CONT_REMAIN)/CONT_PER_C;

return TemperatureSum; }