For the Stetson Startup Pitch we decided to build a computer which could sense both the moisture and the pH content of the soil including, then send that information to an android phone via bluetooth. This was done by using both a YuroBOT moisture sensor, an arduino UNO (from the sparkfun kit borrowed graciously from the Innovation House), a basic PH sensor bought from amazon, a HC-06 bluetooth transmitter and receiver, some resistors, and a basic breadboard.
The sensors were simply plugged into their respective ports on the ardiuno UNO, the bluetooth sensor was used in conjunction with a library found online with all the bluetooth commands needed, and then we found a simple potted plant to test all of our sensors.
After getting all of the sensors to work we calibrated them. For the moisture sensor we simply used the zero value as our lowest value, then to get the maximum value we placed the moisture sensor into a cup of water, after that whatever value we got was divided by our maximum plus our minimum. For the pH sensor we used the difference of the values received over out line to define our value. We then stated our minimum to be coffee (pH value of 5), which there was alot of at the Stetson Startup, and our maximum to be soapy water (pH value of 12). Once all of the sensors were calibrated we then stored the last 40 values and averaged them to display a simple smooth transition of sensor ouput values.
Our current sensor only gets the Moisture, and light amount; only because a pH sensor will slowly degrade over time, and the cheaper the sensor the faster it degrades and the worse the values will be.
Above image is that of the current sensor with an arduino UNO.
Our Stetson Startup team. From left to right David Edwards, Christian Micklisch, and Christian Casadio. Nathan Hilliard is not included, but was also in the team