For the "brains" of my smart greenhouse, I've been considering multiple options. I am currently working with the Raspberry Pi, a great platform but limited in raw performance and potential I/O expansions (note this platform will be placed indoors and communicate using a wireless link with the greenhouse). The other option I've been considering is using a Beaglebone, which is more powerful and has a lot more I/O options (multiple SPI, multiple GPIO etc.).
Another great benefit of the Beaglebone is the onboard eMMC storage, which saves you a memory card (although I currently use a 16GB card).
Challenges with the Beaglebone
Although the Beaglebone is a great platform at a great price point ($45), I have been experiencing several challenges to get the platform to work.
The Angstrom distribution is limited and not all packages are available (at least I couldn't find them). I want to use iPython as an "interactive learning environment" and I couldn't get Numpy to work on Angstrom.
I had some earlier encounters with Angstrom when working with the Beagleboard and I wasn't happy with it (needed a lot of kernel hacking to get all hardware to work properly).
Ubuntu works like a charm, but I had several issues with getting SPI to work properly. The device tree manager has been documented very poorly across the various sites and the older version I used earlier didn't work well with SPI. A newer version (14.01) does work well, but nobody describes what is the correct output.
Finally, the original tiny RTL8192cu dongles seem to work at a glance but have a lot of stability issues when plugging directly in the Beaglebone. Even using extension wires didn't solve the problem. A switch to a NetGear WNA1100 (based on an Atheros chipset) did miracles. I now have a rocksteady connection.
Figure: BeagleBone Black with WNA1100 wifi dongle.
So in the end I have two viable platforms to form the "hub" communicating with the greenhouse. I haven't made my mind up yet which to use. I think it all will depend on how much I want to expand on the central hub. I am thinking of adding a display and potentially some other UI elements and that could benefit greatly from the additional GPIO's from the beaglebone.