The Arduino WiFi Shield has finally arrived and is now available for purchase. The new add-on board – called a “shield” in Arduino terminology – allows the Arduino Uno and Arduino Mega models to connect to 802.11b and g Wi-Fi networks. The WiFi Shield isn’t the first Arduino Wi-Fi module offered for Arduinos: US retailer SparkFun offers the comparable “WiFly Shield” and other wireless modules can be found on the Arduino Shield List. Unlike these modules, however, the Arduino’s official shield uses open source firmware that can be modified via the shield’s on-board Mini-USB connector.
The firmware is located in the AVR 32UC3 Atmel microcontroller that handles the required TCP/IP and Wi-Fi software stack. The board’s Wi-Fi component is an HDG104 by H&D Wireless. The new shield also has a microSD slot that, for example, allows the Arduino to be used as a web server. The SD card and Wi-Fi are connected to the Arduino via the SPI bus and use the 4, 7, 10, 11, 12 and 13 connector pins.
To use the shield, the WiFi Shield Library must be added to the Arduino development environment. The manufacturer says that little effort is required to modify programs that use the Ethernet library for the wired Ethernet shield. The module costs €69 plus VAT from the Arduino Store, but should also be available from various distributors soon. The schematic and reference design are also available.