New devices built on Atmel chips which include RF capability within the microcontroller are growing. The recently successful Pinoccio on Kickstarter is the leader. Others are coming out including miniSWARM on indiegogo. These are compact and have power management built in so they make great nodes in a wireless network. These all seem to be able to talk using the 802.15.4 protocol. An issue is the radio protocol stacks may not have been written to support interoperable communications (for example to a 802.15.4 XBee Series 1 radio) so you really have to review your needs - until these radios talk in an interoperable protocol, mixing and matching may not be possible.
XBee continues to be a very popular choice with strong support via books like Making Things Talk. The platform is well supported with boards and shields. But innovation using XBee is not growing - device cost, 3.3 volt power, and lack of design wins contribute to a bit of stagnation. I like XBees alot and I recommend them for designs. I'd like to see others design current circuits and I'd like to see Digi lower prices to remain competitive.
Wifi continues to be a popular method of communications. The Pinoccio includes a Wifi add-on to connect a local network to a larger Internet network. Other notes:
- The Official Arduino Wifi Shield (802.11b/g) continues to sell at about $85 (Maker Shed)
- DFRobot has a new shield with 802.11 b/g/n also at $85
- Many b/g units in shield, board, and "Bee" form factors
- Prices do not seem to be going down over the last few months.
- The Official Arduino GSM Shield was released into a market with other such cards on the market. There has not been much of an uptake in resellers. The website states Arduino distributors will have it after March 25th but a survey of Sparkfun (which carries other products), Maker Shed, Adafruit, Radioshack all do not have it.
- Yourduino has a shield ($75) and a board ($69)
- SeeedStudio board (Radioshack $90)
- Generic - eBay $45
Small boards based on the nRF24L01+ continue to rise in popularity due to low cost and better software. A new library came out recently from Greg Copeland. Cost for unamplified/chip antenna units are under $3 and modules with an amp and 2dB antenna are around $17-$20 (eBay, Sparkfun and yourduino.com).
- Bluetooth grows in popularity. The new Bluetooth 4.0 low energy is a promising development. The Maker Shed has a nice Arduino Shield at $35
- 315 or 433 MHz transmitters/receivers are also low cost - these are carried by yourduino.com (433), Adafruit (315) and others including eBay.
It's never been a better time to cut the cord on your project and use radio communications. Do research the capabilities of various radios to ensure they'll do what you want.