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WiFi Weather Station

Make a WiFi-connected weather station using Arduino & the CC3000 WiFi chip!

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by M. Schwartz

As open-source hardware users and makers, we love playing with new chips, boards and tools. And there is one chip which is quite popular these days: the CC3000 WiFi chip from TI. This all-in-one module has low-power WiFi and a microcontroller-friendly interface.
It has been featured in many articles around the web, and the Adafruit's CC3000 breakout board really makes it easy to integrate this module in any Arduino project. In this tutorial, you will learn how to use this chip for home automation purposes. And in particular, we are going to see how to use this chip to build a simple WiFi-connected weather station. The station will measure two variables: temperature and humidity. But we won’t display the information on an LCD screen, like a weather station you could buy in a store. No, instead, we will transmit the data wirelessly via WiFi to your computer and display it there on a nice interface. Excited? Let’s get started!

This tutorial is for people who want to use the CC3000 to send data to a basic server script. It's best followed by those who are comfortable setting up a webserver on their computer and running a Node.js server script

Connections

by M. Schwartz

The whole project is based on the Arduino platform, so of course you will need an Arduino board. I really recommend using the Arduino Uno board for this project, as it is the only board that is currently compatible with the CC3000 library at the time this tutorial was written.

Then, you need the Adafruit CC3000 breakout board to make the WiFi communication, and the DHT11 temperature & humidity sensor (you can also use the DHT22 or AM2302 which are almost identical to wire up but higher quality). You also need a 10K Ohm resistor to be used with the DHT sensor.
Finally, you need a breadboard and some jumper wires to make the connections between the different parts.

CC3000 Breakout Board

The hardware configuration of the CC3000 breakout board is relatively easy. Connect the IRQ pin of the CC3000 board to pin number 3 of the Arduino board, VBAT to pin 5, and CS to pin 10.

Then, you need to connect the SPI pins of the board to the corresponding pins on the Arduino board: MOSI, MISO, and CLK go to pins 11,12, and 13, respectively.

Finally, you have to take care of the power supply: Vin goes to the Arduino 5V, and GND to GND.

DHT11 sensor

The DHT sensor is much easier to connect: just plug the pin number 1 to the Arduino’s 5V, pin number 4 to GND, and pin number 2 to Arduino pin 7. Finally, put the 10K resistor between the sensor pins number 1 and 2.

The following picture summarizes the hardware connections:

Testing the hardware

by M. Schwartz

CC3000 WiFi chip

To see if your WiFi chip is correctly wired and operational, I recommend to use the test sketches that come with the Adafruit library that you need to get from GitHub. I used for example the one called WebClient. Just open it from the library’s folder, and save it to a new file (you need to be able to modify the sketch to enter your WiFi network name & password). 

Then, modify the sketch with the correct data for you WiFi network, and upload to the board. You can then open your serial monitor, and if everything was wired correctly (and your Internet connection is working!) you should see your Arduino connecting to the web, then connecting to the Adafruit’s website, and printing some information:

Hello, CC3000!

Free RAM: 1141 bytes

Initializing...

Started AP/SSID scan

Connecting to yourNetwork...Waiting to connect...Connected!

Request DHCP

IP Addr: 192.168.0.2

Netmask: 255.255.255.0

Gateway: 192.168.0.254

DHCPsrv: 192.168.0.254

DNSserv: 192.168.0.254

www.adafruit.com -> 207.58.139.247

Connect to 207.58.139.247:80

-------------------------------------

HTTP/1.1 200 OK

Date: Tue, 17 Sep 2013 09:23:39 GMT

Server: Apache

Access-Control-Allow-Origin: http://learn.adafruit.com

Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, Accept-Encoding, Authorization, Referer, User-Agent

Access-Control-Allow-Methods: GET, POST, OPTIONS

Access-Control-Allow-Credentials: true

Access-Control-Max-Age: 1728000

Last-Modified: Thu, 27 Jun 2013 14:13:27 GMT

Accept-Ranges: bytes

Content-Length: 74

Connection: close

Content-Type: text/html

This is a test of the CC3000 module!

If you can read this, its working :)

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Disconnecting

DHT11 sensor

To use the DHT11 sensor, you need to download the corresponding library first and put it into your /libraries folder inside your Arduino folder. You can use the following sketch to test the DHT11 sensor, update it for DHT22 or AM2302 if you end up using one of those instead

 Download file

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// Include required libraries
#include <SPI.h>
#include <string.h>
#include "DHT.h"
 
// DHT11 sensor pins
#define DHTPIN 7 
#define DHTTYPE DHT11
 
// DHT instance
DHT dht(DHTPIN, DHTTYPE);
                                         
void setup(void)
{
 
  // Initialize DHT sensor
  dht.begin();
  
  Serial.begin(115200);
  
}
  
void loop(void)
{
  
    // Measure the humidity & temperature
    float h = dht.readHumidity();
    float t = dht.readTemperature();
   
    // Transform to String
    String temp = String((int) t);
    String hum = String((int) h);
    
    Serial.print("Temperature: ");
    Serial.println(temp);
    Serial.print("Humidity: ");
    Serial.println(hum);
    Serial.println("");
  
}

Upload this sketch to the Arduino board, open the serial monitor and select 115200 baud, and this is what you should see:

Temperature: 21

Humidity: 23

Temperature: 21

Humidity: 23

Temperature: 21

Humidity: 22

Temperature: 21

Humidity: 23

Temperature: 21

Humidity: 23

Temperature: 21

Humidity: 23

Temperature: 21

Humidity: 23

If you can't communicate with the sensor, or the data looks really wrong, check your wiring and code until it works. It has to work before we continue!