I have been looking into wireless sensor networks for some time, and I definitely need to jump into the wagon and order some development kits to play/experiment and build some prototypes. 802.15.4 is the radio layer used by Zigbee. I am not constrained to using specifically Zigbee and I prefer open-source stacks, but I would like to stay with 802.15.4 as it is more widespread than other technologies like DASH7. My current hardware options are:
- Libelium. The Squidbee motes provide a prototyping solution based on Arduino, which is designed for teaching and educational purposes, while Waspmote is their commercial platform. They look very efficient and well built , with good documentation and support.
- Openpicus. These guys provide an interesting platform for prototyping based on open-source software running FreeRTOS.
- Some of the platforms based on TI’s CC2420 chip.
Wireless sensor networks need to be programmed in an efficient way due to the limited processing, storage and power resources of a typical sensor node, which is difficult to accomplish using high-level languages. Normally C or a specific dialect like e.g. nesC (used on TinyOS) is needed. The operating systems used on the different wireless sensor platforms can be split between free academic implementations, like TinyOs or Contiki, and proprietary OS layers used on Zigbee stacks, like TI´s Z-Stack, Freescale or Ember´s stack. These proprietary implementations don´t provide an unified C API, the only Zigbee compliance requirement being a correct over-the-air behavior. There have been some attempts at building an open-source Zigbee stack, but I am not aware of a successful one.
An interesting project is zigbee-linux, although it has a misleading name as it only covers 802.15.4. Zigbee itself is not compatible with the GPL, but there are efforts underway to bring to the table alternative protocols which are built on top of 802.15.4 and are GPL compatible, like 6lowpan/ROLL. One good option I have found for running an open wireless sensor network stack is SICSLoWPAN, an open-source IPv6 over 802.15.4 stack.
What do you think? Any platform you can recommend?