Customized LM393D Soil Moisture Sensor Board

Elevator

The project is good at converting analog signals from the soil to digital signals for soil moisture data processing.

Introduction

Soil probes that generate analog data signals have been used in studying soil moisture. Many users of these probes have had difficulties converting the obtained analog data into digital data. In this project, we will design a module to do that. This module is a soil moisture sensor board that can solve your smart irrigation system challenges. The sensor can be incorporated with an Arduino development board for programming purposes, which will be good for automating your irrigation system. My focus is on how to design such a soil moisture sensor. For programming, you can find that in various Arduino forums. We shall discuss the sensor required components, the circuit, how the circuit works, how to convert such circuit into PCB, and how to order your PCB for manufacturing through PCBWay.

Soil Moisture Sensor Required Components

• 104 Unpolarized capacitors, small symbol C1, C2 C_0402_1005Metric
• Trigger LED Light emitting diode, small symbol D1 LED_0402 1005Metric
• Power LED Light emitting diode, small symbol D2 LED_0402_1005Metric
• Moisture Probe In Generic connector, single row, 01x02, script generated (kicad-library-utils/schlib/autogen/connector/) J1 PinHeader_1x02_P2.54mm_Horizontal
• Conn_01x04 Generic connector, single row, 01x04, script generated (kicad-library-utils/schlib/autogen/connector/) J2 TE_282834-4 10k Resistor, small US symbol R1 R_0402_1005Metric
• 1k Resistor, small US symbol R2, R3 R_0402_1005Metric
• 10k Trim-potentiometer, US symbol RV1 Potentiometer_Bourns_3266Y_Vertical LM393 Low-Power, Low-Offset Voltage, Dual Comparators, DIP-8/SOIC-8/TO-99-8 U1 SOT-223-8

Soil Moisture Sensor Circuit

Attached below is the circuit diagram for the soil moisture sensor board circuit.📷

The circuit uses KiCAD EDA and can be generated using a few common electronic components. The board is built around LM393D op-amp, powered by a voltage range between 3V3 and 5V. The LM393D converts the input analog signal originating from the sensor probe fixed on the sensor board and soil to the required digital signals.

The work of the 10k potentiometer is to act as a reference voltage setter for the LM393D op-amp. When the input voltage of the operational amplifier is below the preset value of the potentiometer, then the operational amplifier output goes low.

On the same board, we have a pair of LEDs. The first important LED is the power, and the other is the Trigger one. The power LED indicates when the board is powered, while the trigger LED indicates when a certain threshold is achieved.

Soil Moisture Sensor Board Pinout

Your sensor should have four important pinouts: VCC, GND, D_OUT, and A_OUT. The pinout is as shown in the figure below:

The function of each pin is as discussed below:

• VCC- This is the pin that supplies power to the module. The pin is connected to a 3V3 and 5V power supply. This is connected to the 5V pin of the Arduino.
• D_OUT- This is the digital pinout. When the output from this pin is high, the soil moisture is low, while if the output is low, the soil moisture is high.
• A_OUT- This is the analog pinout. The function of this pin is to give analog signals.
• GND- This is the ground pinout of the module. This is connected to the Arduino ground pin.

Order for manufacturing

After generating all the manufacturing files, I moved to the PCBway home page to order for the manufacturing through the online instant quote page. Here, I started by inputting the size of the board, selecting the material and quantity of the boards, and selecting the layers of my board.

Click calculate to get the first quote, then hit save to cart. Then, another window will pop out where you need to submit your Gerber files for the team of experts to review and give you a final quote.

Upload the Gerber file, submit it, and wait for the quote to be completed. Make payment as required through various available payment methods and wait for the order to be delivered in seven days.