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Web Client to consume Weather Underground web service (RESTful and JSON formats). This sketch connects to a website (http://api.wunderground.com) using an Arduino + Ethernet shield and get data from site. Circuit: * Arduino MEGA 2560 R3 Board. * Ethernet shield attached to pins 10, 11, 12, 13. Created 07 Jan 2014 by Afonso C. Turcato. Arduino ID…
/*
Web Client to consume Weather Underground web service
This sketch connects to a website (http://api.wunderground.com)
using an Arduino Ethernet shield and get data from site.
Circuit:
* Arduino MEGA 2560 R3 Board
* Ethernet shield attached to pins 10, 11, 12, 13
created 07 Jan 2014
by Afonso C. Turcato
*/
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
// 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(23,216,168,120); // numeric IP for Weather Underground (no DNS)
const char server[] = "api.wunderground.com"; // name address for Weather Underground (using DNS)
const String myKey = "xxxxxxxxxxxxxxxx"; //See: http://www.wunderground.com/weather/api/d/docs (change here with your KEY)
const String myFeatures = "conditions"; //See: http://www.wunderground.com/weather/api/d/docs?d=data/index&MR=1
const String myCountry = "Brazil"; //See: http://www.wunderground.com/weather/api/d/docs?d=resources/country-to-iso-matching
const String myCity = "Sertaozinho"; //See: http://www.wunderground.com/weather/api/d/docs?d=data/index&MR=1
// Set the static IP address to use if the DHCP fails to assign
IPAddress ip(192,168,1,177);
// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;
//Response from Server
String responseString;
boolean startCapture;
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(9600);
// start the Ethernet connection:
if (Ethernet.begin(mac) == 0)
{
Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
// try to congifure using IP address instead of DHCP:
Ethernet.begin(mac, ip);
}
// give the Ethernet shield a half-second to initialize:
delay(500);
Serial.print("My IP Address is: ");
Serial.println(Ethernet.localIP());
Serial.println("Connecting...");
// if you get a connection, report back via serial:
if (client.connect(server, 80))
{
Serial.println("Connected!");
String html_cmd1 = "GET /api/" + myKey + "/" + myFeatures + "/q/" + myCountry + "/" + myCity + ".json HTTP/1.1";
String html_cmd2 = "Host: " + (String)server;
String html_cmd3 = "Connection: close";
//Uncomment this is necessary
//Serial.println("Sending commands:");
//Serial.println(" " + html_cmd1);
//Serial.println(" " + html_cmd2);
//Serial.println(" " + html_cmd3);
//Serial.println();
// Make a HTTP request:
client.println(html_cmd1);
client.println(html_cmd2);
client.println(html_cmd3);
client.println();
responseString = "";
startCapture = false;
}
else
{
// if you didn't get a connection to the server:
Serial.println("Connection failed!");
}
}
void loop()
{
// if there are incoming bytes available
// from the server, read them and buffer:
if (client.available())
{
char c = client.read();
if(c == '{')
startCapture=true;
if(startCapture)
responseString += c;
}
// if the server's disconnected, stop the client:
if (!client.connected()) {
Serial.println("Received " + (String)responseString.length() + " bytes");
Serial.println("Disconnecting.");
client.stop();
client.flush();
Serial.println();
//Now, some examples of how to use it!
Serial.print("Weather: ");
Serial.println(getValuesFromKey(responseString, "weather"));
Serial.println();
Serial.print("Current Temperature: ");
Serial.print(getValuesFromKey(responseString, "temp_c"));
Serial.println(" oC\n");
Serial.print("Relativy Humidity: ");
Serial.println(getValuesFromKey(responseString, "relative_humidity"));
Serial.println();
Serial.print("Wind: ");
Serial.println(getValuesFromKey(responseString, "wind_string"));
Serial.println();
Serial.print("Feels like: ");
Serial.print(getValuesFromKey(responseString, "feelslike_c"));
Serial.println(" oC\n");
// do nothing forevermore:
while(true);
}
}
String getValuesFromKey(const String response, const String sKey)
{
String sKey_ = sKey;
sKey_ = "\"" + sKey + "\":";
char key[sKey_.length()];
sKey_.toCharArray(key, sizeof(key));
int keySize = sizeof(key)-1;
String result = NULL;
int n = response.length();
for(int i=0; i < (n-keySize-1); i++)
{
char c[keySize];
for(int k=0; k<keySize; k++)
{
c[k] = response.charAt(i+k);
}
boolean isEqual = true;
for(int k=0; k<keySize; k++)
{
if(!(c[k] == key[k]))
{
isEqual = false;
break;
}
}
if(isEqual)
{
int j= i + keySize + 1;
while(!(response.charAt(j) == ','))
{
result += response.charAt(j);
j++;
}
//Remove char '"'
result.replace("\"","");
break;
}
}
return result;
}

Fine!!!Any change necessary on sketch for using with my Arduino Uno R3?
Thanks!
Julio

Hi Afonso, thanks for getValuesFromKey :)

Hi, this code return many errors during compilation. I have the Mega and Ethernet shield and not sure what is wrong.
for instance in
"String result = NULL;
conversion from 'int' to 'String' is ambiguous."

Also, I am looking a code like this but using the ESP8266. I tried to use this original code as a base but made a mess. I am fairly new to Arduino and still dont understand many things.
I have not found a good library to use the ESP8266 with the same tools as the Ethernet.
Can you indicate me the correct direction to follow?
Thanks
Jose.

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