We are now going to build the Arduino sketch for this project. The goal is to measure data on the Arduino board, connect with the Xively server, and send the data.

The first step is to include the following required libraries:

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

Enter the MAC address of your board:

byte mac[] = { 0x90, 0xA2, 0xDA, 0x0E, 0xFE, 0x40 };

We can then define the pin and the type of the DHT sensor as follows:

#define DHTPIN 7
#define DHTTYPE DHT11

Create an instance on the sensor, as shown in the following line:

DHT dht(DHTPIN, DHTTYPE);

Create an instance of the Ethernet client:

EthernetClient client;

We also define a default IP address for the board:

IPAddress ip(192,168,1,50);

In the sketch, we also set the address of the secured Xively server that we will connect to using the Ethernet shield:

IPAddress server(216,52,233,120);

Now, we have to modify the sketch a little bit to enter your own information about your Xively account. This is...