SmartWater

Most people have heard Earth referred to as ‘the water planet’ and have seen numerous images from space with our planet dominated by blue seas. Humans depend on water to survive and we are intimately tied to the substance by the water molecules cycling through our bodies. Thus, it is inconceivable to think that less than three percent of Earth’s water is freshwater. Furthermore, most of this three percent is trapped in ice caps, glaciers and groundwater. Thus, majority of life on Earth is sustained by only 0.3% of water available on Earth. With this distressing realization comes a recognition that we have use this scarce resource wisely.

The WaterSmart System is simply designed plant watering device. It is controlled by an Arduino Uno, an open source microcontroller board based on the Microchip ATmega328P.

In the input pin of the Arduino an FC-28 Soil moisture sensor is connected. The soil moisture sensor has two probes which calculates the volumetric content of water in the soil and gives us an output. The FC-28 sensor gives an analogue output. The two probes allow current to pass through the soil and then the moisture value.

When the level of moisture in the soil is high it conducts more electricity offering less resistance. When the water level is low the conduction of electricity is low offering more resistance. The FC- 28 calculates this resistance and determines the level of water.

The output pin of the Arduino is the power relay module. A power relay module is an electric switch that is operated by an electromagnet. The electromagnet is activated by a separate low- power signal from a micro controller (here Arduino Uno).

When activated, the electromagnet pulls to either open or close an electrical circuit. A 12v pump which is connected to an external power source has the ground wire going through the relay model. The Arduino checks the moisture level of the soil every 15 minutes and it is lower than a given threshold it signals the relay module to complete the circuit of the pump which as a result waters the plant.

The Arduino is powered by a 5v power supply which also powers the moisture sensor and the relay module. The positive pin of the Arduino is connected to a breadboard to which the positive terminals of both the moisture sensor and the power relay module is connected so that the power is sent to both the sensor and the relay module as there is only one port for the positive pin on the Arduino. The ground pin of both the sensor and the relay module have individual pins on the Arduino.