Soil Moisture Sensor

Plants require water on a regular basis for proper growth. This soil moisture sensor used to measure moisture or water level content in it. When the moisture level is high, the module gives a digital output of 5V and provides 0V when the moisture level is low in the soil.

This sensor consists of two probes used to measure the volumetric water content in the soil. It measures the moisture content without removing moisture, by using other parameters of soil like electrical resistance or conductance, dielectric constant, and interaction with other neutrons. The output may vary depending on environmental factors like soil type, temperature, and conductivity, hence it has to be calibrated. The soil sensor provides both analogue and digital outputs.

The two probes allow the current to pass through the soil and then the moisture level measured using the resistance value obtained. When the water content is more, the soil will conduct more electricity thus providing less resistance. Therefore, the moisture level will be higher. When the water content is low, Dry soil conducts electricity poorly, which means that there will be more resistance. Therefore, the moisture level will be lower. The sensor includes an onboard potentiometer to set the desired moisture threshold value and this value will be compared by the LM393 comparator. The output LED will light up and down according to this threshold value.

When the moisture content is more than the set threshold, the digital output goes high and an LED indicates the output. When the moisture in the soil goes below the threshold, the output remains low. The digital output is further connected to a microcontroller to sense the moisture level. The sensor also outputs an analog output connected to the ADC for the precise moisture content value.

PIN DESCRIPTION:

• • VCC pin is used for power
  • A0 pin is an analogue output
  • D0 pin is a digital output
  • GND pin is a Ground