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Class 13: Wireless 1 - WiFi

Slides: 

Working with the nRF24L01 Serial module

Connecting directly to the Web with the CC3000 WiFi breakout board

  • You will connect using the open CalVisitor wireless network, which is available all over campus, but has some restrictions - you may not be able to access ports outside http and https (ports 80 and 443). You cannot use AirBears or AirBears2 - the hardware does not support web login or WPA2 Enterprise authentication. 
  • We also have a backup network called "idd-local" with WPA2 Personal key "devicedesign". It isn't connected to the internet, but we have a local server running at 192.168.1.101.

Wire up the breakout board

  • Solder header pins that face downwards (so you can place the module into a breadboard with the CC3000 facing up).
  • Adafruit has a detailed CC3000 Wiring Tutorial for Arduino - the given pin numbers will work on your mbed. For reference:

From CC3000 to mbed:

    • IRQ => (pin D3)
    • Enable => (pin D5)
    • SPI CS => (pin D10)
    • SPI MOSI => (pin D11)
    • SPI MISO => (pin D12)
    • SPI CLK => (pin D13 - this is also the blue LED (a design flaw); use PTC5 alternatively)
    • VIN => 5V or Vin
    • GND => GND

Simple Demo: Confirm that you can get online

  • Import this demo CC3000 Demo.
  • Change the 30th line's SSID and PASSWORD and SECURITY to:
      • "CalVisitor", "", and NONE to get online
      • "idd-local", "devicedesign" and WPA2 to use our local in-room network.
  • Compile and download the program. When you run it, a successful run will look like this:
C3000 Sample Program
IP address: 128.32.XX.XXX
>

If you have problems, you can get debug output to appear by editing cc3000.h to change debug output from 0 to 1 (there are a number of different debug levels you can show):

// Debug - General Debug
#define CC3000_DEBUG        1  // Change from 0 to 1

Once you are online, you can type a URL and hit enter. (copy & paste might be better)

> Requested http://husk.eecs.berkeley.edu/projects/cc3000/hello.txt
Page fetched successfully - read 16 characters
Result: Hello, CC3000!

The first request might return an error state. It has something to do with the library we are using (HTTPClient is buggy)

> Error - ret = 8 - HTTP return code = 0

Using the CC3000 as a Web Client

Get data from a web server

You've done it with the above template code.

Send data to a web server using CC3000
  • The easiest way to send data to a web server is to encode it as URL parameters in a GET request as follows:
GET /relative_path?param1=value&param2=value&param3=value... HTTP/1.1
  • URL parameters and values need to be URL-encoded according to RFC3986. Here's a C implementation.
  • You already have an HTTPClient library, which takes care of some of this for you. You can simply execute:
char url[]="http://husk.eecs.berkeley.edu/projects/cc3000/sendchat.php?msg=ON";
int ret = http.get(url, str, 128); //str is where up to 128 bytes of results will be stored
Parse structured data received from a web server

Additional Server Code Examples

We have code examples of various server setups (written for Arduino hardware) in a git repo at:

   https://github.com/bjo3rn/idd-examples/