Maintenance of Soil Water Content with Automatic Irrigation and Soil Moisture Sensor

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Maintenance of Soil Water Content with Automatic Irrigation and Soil Moisture Sensor
DISUSSION
Power Supply. The power supply is connected to the microcontroller which then connected to the water pump driver and sensors. It is made of a 12/5 V battery which is used to drive the motor. The battery is charged using a photovoltaic cell which helps to convert light energy into electricity. According to (Balaji and Sudha 203), the power supply system provides electricity to be used for pumping water and transmitting signals. A charge controller within the panel helps to regulate the amount of solar power to the 12/5V battery. It maintains desirable amounts of current and voltage to ensure adequate power is supplied and longer battery life.
The power supply is also made of a boost converter which is used to step up the voltage from the input to its output. It ensures that a higher voltage is delivered to the battery when the photovoltaic cell receives less light. The boost converter is made of a transistor, a diode, and a capacitor, all in one unit. The voltage output ripple is reduced by using filters. The converter has two resistance values to help control the amount of power from the solar panel. The voltage from the booster is stored in the 12/5v battery. A regulator is also provided to regulate the voltage from 12 V to 5 V with the assistance of a current limiting resistor (Balaji and Sudha 204). Power emanating from the regulator is used to operate the microcontroller.

Moisture Sensor. The moisture sensor is buried in the ground at a predetermined depth. This automated irrigation system uses a moisture sensor which is based on the frequency domain reflector technology. The FDR sensor features two metal rods where the electric current runs through to the soil. It uses the soil as a capacitor and changes in the frequency of the electric wave are a function of its capacitance and dielectric properties (Sample et.al. 3). A higher frequency means a higher soil moisture. Accuracy is guaranteed after calibration to the specific soil. The sensor uses immersion gold material to prevent nickel from oxidation. It remains functional even in untreated contact surfaces.
The sensor reads the amount of moisture present in the soil and relays a signal back to the microcontroller which in turn sends the desired signal to the pump. The two probes are used to pass current to the soil. More water content produces less electric resistance. Dry soil conducts electricity poorly which leads to more electrical resistance. The moisture sensor module has a higher sensitivity and consumes less power. It works at a depth of 37mm and temperature range of 10-30°C. There is a 3 pin dual-female wire measuring used to connect the moisture sensor to an Arduino sensor shield.
Signal Lines. Lines in the system diagram represent signal and resource flow. A signal from the microcontroller to the water pump describes whether the microcontroller needs to drive the pump or not. The microcontroller receives an input signal of “moisture low” to output a signal of “drive high” which activates the relay thus sending an output signal to turn on the water pump driver. A “water low” signal is sent from the water level sensor which helps to start or keep the pump running. A “moisture low “signal is also sent from the moisture sensor to activate and keep the pump running. According to Balaji and Sudha (2016), the signal from the microcontroller to relay sets the motor pump to on and off. This is enabled by the transmission of the “pump drive” signal which activates the pump. A “pump drive” signal is transmitted from the water pump driver to the water pump.
Works Cited
Balaji, V. R., and M. Sudha. “Solar powered auto irrigation system.” International Journal of Emerging Technology in Computer Science & Electronics (IJETCSE) 20.2 (2016).
Sample, David, et al. “Understanding Soil Moisture Sensors: A Fact Sheet for Irrigation Professionals in Virginia.” (2016).