Category: interactive media art

[Note: xively.com is gone. This system doesn’t work. Post is here for historical reasons only]

Bi-directional communication from Arduino to a xively.com feed using an ethernet shield.

• Initializes an internet connection (DHCP)
• Connects to xively.com servers every minute
• Stores random value in the feed using HTTP PUT
• Retrieves current feed value using HTTP GET
• Lights up LED when transmitting

Arduino circuit

• Use an ethernet shield.
• Connect ethernet cable. (I am using a Netgear WNCE2001 ethernet to wiFi adapter)
• LED is connected to pin 5 and ground. The shorter lead connects to ground.

1. Connect Arduino to Macbook via USB.
2. Open the Arduino serial monitor to initialize the ethernet connection and display the IP address.
3. Every minute data gets send to the feed
4. Monitor feed data here: https://xively.com/feeds/98281/workbench

Arduino sketch

/*
5/20/2014 - Arduino/xively feed interaction

Uses Ethernet Shield and and LED connected between pin D5 and ground

Sends a random value to a xively.com feed every minute
The LED lights up during data transmissions

demonstrates:

HTTP PUT - send data to xiveyly feed and store
HTTP GET - read xively feed value

*/

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

int ledPin = 5;

int upCount = 0; // counters for number of times going up and down

#define API_KEY "96PqSh4rj7HzNif3WtTpN7GjX96SAKxrWms3SUhwaDFGUT0g" // your Cosm API key
#define FEED_ID 98281 // your Cosm feed ID

// MAC address for your Ethernet shield
byte mac[] = { 0x90, 0xA2, 0xDA, 0x0D, 0x0B, 0xCE };

// note that pins 0 and 1 are used by the Ethernet shield

unsigned long lastConnectionTime = 0; // last time we connected to Cosm
const unsigned long connectionInterval = 60000; // delay between connecting to Cosm in milliseconds

// Initialize the Cosm library

// Define the string for our datastream ID
char sensorId[] = "count";

CosmDatastream datastreams[] = {
 CosmDatastream(sensorId, strlen(sensorId), DATASTREAM_FLOAT),
};

// Wrap the datastream into a feed
CosmFeed feed(FEED_ID, datastreams, 1 /* number of datastreams */);

EthernetClient client;
CosmClient cosmclient(client);

void setup() {

 // initialize the detector pins 

 pinMode(ledPin, OUTPUT ); // internet transmitting indicator
 // start the Monitor (console) serial port

 Serial.begin(9600);

// display happy messages 

 Serial.println("Xively test");
 Serial.println("==========================");

// Keep trying to initialize the Internet connection
 // Note - we should eventually timeout of this and just run the stairs independently

 Serial.println("Initializing network");
 while (Ethernet.begin(mac) != 1) {
 Serial.println("Error getting IP address via DHCP, trying again...");
 delay(15000);
 }

Serial.println("Network initialized");
 Serial.println();
 // print your local IP address:
 Serial.print("Arduino IP address: ");
 for (byte thisByte = 0; thisByte < 4; thisByte++) {
 // print the value of each byte of the IP address:
 Serial.print(Ethernet.localIP()[thisByte], DEC);
 Serial.print("."); 
 }
 Serial.println();
 Serial.println();

} // end of setup function

//////////////////////////// control loop ///////////////////////////

void loop() {
 // main program loop

 ////////////////////////////// Internet sending/receiving code ////////////////////////////////

 if (millis() - lastConnectionTime > connectionInterval) {

 // uncomment this to just send a random value...
 upCount = random(256);

 digitalWrite(ledPin, HIGH ); // turn on transmitter light
 sendData(upCount);
 // read the datastream back from Cosm - comment out to save time
 getData();
 digitalWrite(ledPin, LOW );
 // update connection time so we wait before connecting again
 lastConnectionTime = millis();

 }

 ///////////////////// end of internet send/receive code /////////////////

} // end of main loop code

/////////////////// additional functions //////////////////////////
////////////////////////////////////////////////////////////////////

// send the supplied value to Cosm, printing some debug information as we go
void sendData(int sensorValue) {
 datastreams[0].setFloat(sensorValue);

Serial.print("Read sensor value ");
 Serial.println(datastreams[0].getFloat());

Serial.println("Uploading to Cosm");
 int ret = cosmclient.put(feed, API_KEY);
 Serial.print("PUT return code: ");
 Serial.println(ret);

Serial.println();
}

// get the value of the datastream from Cosm, printing out the value we received
void getData() {
 Serial.println("Reading data from Cosm");

int ret = cosmclient.get(feed, API_KEY);
 Serial.print("GET return code: ");
 Serial.println(ret);

if (ret > 0) {
 Serial.print("Datastream is: ");
 Serial.println(feed[0]);

Serial.print("Sensor value is: ");
 Serial.println(feed[0].getFloat());
 }

Serial.println();
}