Analog sensors are devices that are capable of returning an analog signal that is proportional to the measured entity. Then, the analog signal should be converted into a digital one using proper circuitry or, for simplicity, an AD.
A moisture sensor is a device that can change its internal resistance according to the wet intensity of the soil moisture:
Note
The device can be purchased at http://www.cosino.io/product/moisture-sensor or by surfing the Internet. The user guide of this device is available at http://seeedstudio.com/wiki/Grove_-_Moisture_Sensor .
This device is quite similar to the water sensor presented in the preceding section since the functioning is still based on the water conductivity. However, its shape is different because we are interested to know the soil humidity level in place of the water present status.
The connections to the SAMA5D3 Xplained are reported in the following diagram:
After all the connections are in place, we can read...