This week was about taking some input and measuring it. For my final project sprint, I knew that I wanted to use a soil moisture sensor to optimize the amount of water that my plants get. Theoretically, I could directly test putting it into my finalized board with the ESP32, but before I milled that I wanted to make sure the sensor was working and giving me some values that made sense (spoiler alert: it worked easily, but not so easily when I moved over to the ESP32 just a bit later).

After connecting the sensor, which had a 5V input, and analog output, to a valid ADC pin on my board from week 6, I was able to get some nice values from the sensor. When I wrapped a damp cloth around it, the value went down, and when I wrapped a dry cloth around it, the value went up. This was the opposite kind of behavior that was intuitive to me with a "moisture" sensor measuring inverse moisture, but it made sense when I thought about it. The sensor is discharges a capacitor, and the more moisture in the soil, the more it will discharge. So, the more moisture, the lower the voltage, and the less moisture, the higher the voltage.

This was a good first step to learning about sensors and interfacing with them -- especially for my final project.