These week I focused primarily on what I need to start actually building the for-field-use soil moisture/temperature sensor platform, as well as selecting a bluetooth shield for communicating with our field science app, and picking a board to actually build the platform on.
I tracked down circuit schematics for the Infrared temperature sensor. So far I think it will work for our purposes, and at around ~$3 a unit I see no reason not to try it out.
We already have several moisture (and temp – a useful calibration for the IR measurements) sensing platforms laying around so I will probably cannibalize one of those for it’s sensor. I just need to figure out which one…
My next order of business is selecting the best bluetooth shield for this project. I’m looking at Bluetooth LE (low energy) because we don’t want it to die in the field. The LightBlue Bean that Kristin found for the Ambiance platform looks promising – it has extra functionality built in that might not be necessary for bench-top applications but could be useful out in the field. Even though the ambiance platform will have a LightBlue Bean sending back temperature and accelerometer data, it might be nice to have this data associated with a sensor value on the ground as well. Also the onboard battery is very nice. I’ve been looking at other shields but I think I need a second set of more knowledgeable eyes to discern which ones might work best for bench applications.
Up until now we have primarily used the Arduino Yun for field sensors because of it’s wifi capabilities, which are handy for in-field debugging. Now that we are moving towards bluetooth, this is no longer necessary. I was thinking about using the Arduino UNO. This seems to be the flagship board from Arduino, and is advertised as being the best for beginners (which I am). I also know we have lots of them around already, which will make it easier to get started right away.