The soil moisture sensor is commonly used in smart agriculture or other garden automation projects to measure the moisture content present in the soil. It consists of 4 pins in which two pins, Vcc and Gnd are connected to supply voltage. The remaining two pins are digital (D0) and analog (A0) are the output pins. When the moisture content present in the soil goes beyond the threshold level, the output of the digital pin (D0) will go low (the output of the digital pin is either logic 0 or 1). The threshold value of the sensor module can be set by varying the onboard potentiometer. The analog output pin can be used to calculate the approximate level of moisture content present in the soil.
 
Specifications:-
Operating voltage: 3.3V~5V
Dual output mode,analog output more accurate
A fixed bolt hole for easy installation
With power indicator (red) and digital switching output indicator (green)
Having LM393 comparator chip, stable
Panel PCB Dimension: Approx.3cm x 1.5cm
Soil Probe Dimension: Approx. 6cm x 3cm
Cable Length: Approx.21cm
VCC: 3.3V-5V
GND: GND
DO: digital output interface(0 and 1)
AO: analog output interface
 
 
Connections:-
VCC  connect to 3.3V-5V
GND  connect to GND
DO   digital value output connector（0 or 1）
AO  analog value output connector