I spent several hours today exploring the Crossbow Imote2 .Builder Kit, a "complete development environment for high performance wireless sensor networking (WSN) applications leveraging the Microsoft .NET Framework," as the company describes it.
(I'd never say "leveraging" and "Microsoft" in the same sentence myself if I could avoid it, because of Microsoft's rather checkered legal history of "leveraging" its near-monopoly -- but oops, I did it again. Back to Crossbow.)
The Imote2 .Builder Kit sells for US$990 in the US in small quantities. It includes three Imote2 processor boards, two Imote2 sensor boards, two battery boards, batteries, a USB cable, and software on CD-ROM. Obviously, individual boards are cheaper, especially in quantity.
Why so many boards? The processor boards also have radios, and can talk to each other using the 802.15.4 protocol. The Imote2 has an XScale CPU @ [13-416] MHz and a DSP, 256kB SRAM, 32 MB of SDRAM and 32 MB of FLASH, and baker's dozen of I/O ports of various stripes in addition to the radio and antenna. It has two pairs of connectors for sensor boards, a set for a "basic sensor board" on one side and an "advanced sensor board" on the other side. The flash image includes the .NET Micro Framework.
The sensor boards that come with the kit are of the basic variety, but I guess that refers to the connector they use: they actually have a 3d Accelerometer, an advanced temp/humidity sensor, a light sensor and 4 channel A/D.
The Imote2 software is an add-on to Microsoft Visual Studio 2005 (yes, 2005, not 2008) and .NET Micro Framework 2.0 (yes, 2.0, not 2.5). A 90-day trial version of Visual Studio 2005 Professional is provided with the kit.
I found the programming model for the Imote2 easy to understand, as I was already fluent in C# and familiar with Visual Studio 2005 and the .NET Micro Framework. I think I could build wireless sensor network applications with this kit very quickly: in days to weeks, depending on the complexity of the application.
The processors seem plenty fast. Debugging is trivially easy. The only trouble I had with the kit was a minor but annoying deployment issue: sometimes a board would stop taking downloads, and code deployment from Visual Studio would fail. I was always able to recover from this by stopping all the software on the PC that talked to the board, disconnecting the board from the USB bus, reconnecting and resetting the board, and restarting the software.
According to the company, this is most likely a problem with the Microsoft USBSPOT driver. Once I had a board programmed, it would be fine.
This picture is of the hardware configuration for the most advanced demo in the kit, a star network in which two battery-powered CPU/sensor stacks transmit accelerometer data, one CPU board receives the signals and sends them over the USB cable, and the PC plots the live output.
Overall, this is a very impressive kit. There's more information at the Crossbow site.