ESP8266 The cheapest WiFi module for your Arduino
The last few weeks there is a lot of buzz around a new module which gives WiFi access to your Arduino controller via serial port. the name of it is ESP8266 and its main advantage is the very low price. Less than 3$ dollars. Comparing that to 30+ dollars of a wifi shield cost is something that makes it instantly desirable! (Shut up and take my money!). Of course you should not expect top performance since all the communication is done via serial port which has a limit of 115200bps. Many respectable makers already own one of these modules and it seems that for simple applications works fine. Ray Wang has a very nice post in his website and I suggest you go through it.
What is Serial-to-WiFi? Simply put, it means using serial TX/RX to send and receive Ethernet buffers, and similarly, using serial commands to query and change configurations of the WiFi module. This is quite convenient as it only requires two wires (TX/RX) to communicate between a microcontroller and WiFi, but more importantly, it offloads WiFi-related tasks to the module, allowing the microcontroller code to be very light-weighted.
I already ordered a pair few weeks ago but still waiting, so I’ll update this post as soon as i have them. More information about ESP8266 here