[RISOLTO] Problema con Ethernet Shield, DHCP e Xively

Sto tentando di caricare dei dati letti da un sensore su Xively, ma ho riscontrato diversi problemi:

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

#define APIKEY         "0wdgZk5cfhah4l3nr-----------------------------------" // replace your pachube api key here
#define FEEDID         1339----- // replace your feed ID
#define USERAGENT      "Temperatura" // user agent is the project name

// assign a MAC address for the ethernet controller.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
// fill in your address here:
byte mac[] = { 
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};

// fill in an available IP address on your network here,
// for manual configuration:
IPAddress ip(192,168,1,210);
// initialize the library instance:
EthernetClient client;

// if you don't want to use DNS (and reduce your sketch size)
// use the numeric IP instead of the name for the server:
IPAddress server(64,94,18,120);      // numeric IP for api.pachube.com
//char server[] = "api.xively.com";   // name address for pachube API

unsigned 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 unsigned long postingInterval = 10*1000; //delay between updates to Pachube.com

void setup() {
 // Open serial communications and wait for port to open:
   while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only

 // start the Ethernet connection:
  if (Ethernet.begin(mac) == 0) {
   Serial.println("Failed to configure Ethernet using DHCP");
    DHCP failed, so use a fixed IP address:
    //Ethernet.begin(mac, ip);

void loop() {
  // read the analog sensor:
  int sensorReading = analogRead(A0);   

  // 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();

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

  // 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)) {
  // 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(server, 80)) {
    // send the HTTP PUT request:
    client.print("PUT /v2/feeds/");
    client.println(".csv HTTP/1.1");
    client.println("Host: api.pachube.com");
    client.print("X-PachubeApiKey: ");
    client.print("User-Agent: ");
    client.print("Content-Length: ");

    // calculate the length of the sensor reading in bytes:
    // 8 bytes for "sensor1," + number of digits of the data:
    int thisLength = 8 + getLength(thisData);

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

    // here's the actual content of the PUT request:
  else {
    // if you couldn't make a connection:
    Serial.println("connection failed");
   // note the time that the connection was made or attempted:
  lastConnectionTime = millis();

// 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;
  // return the number of digits:
  return digits;

lo sketch è quello PachubeClient installato di default nell’ IDE, a cui ho corretto la API KEY, il Feed ID e lo USERAGENT (su xively sarebbe la voce “channel” ?).
e ho riscontrato questi problemi:

  1. Non riesco ad ottenere un IP dal server DHCP (il router di casa)
  2. Nonostante l’ip di Arduino configurato manualmente non accade nulla, e Arduino risponde:
connection failed


se invece uso il file DatastreamUpload incluso nelle librerie di xively risponde:

Read sensor value 296.00
Uploading it to Xively
xivelyclient.put returned -1

EDIT: usando un collegamento diretto da Arduino al router senza passare per uno switch tutto funziona correttamente