Automated Plant Watering System

Introduction 

 

The majority of individuals are too sluggish in the summer to regularly water the potted plants in their rooftop gardens. This section explains how to construct a quick and easy automated plant watering system that takes just a few hours. It is an autonomous plant watering system powered by Arduino that measures soil moisture. 

 displays the prototype created by the author.

 

 

Automatic plant watering system circuit and working.

 

 

Fig. 2 depicts the circuit diagram of the automated plant watering system. The circuit consists of a 12V water pump, a servo motor, an Arduino UNO board, a soil moisture sensor, and an L293D (IC1) motor driver IC.

 

Circuit diagram of the automatic plants watering system

An Arduino board may be powered by a 7V to 12V wall wart, plug-in converter, or solar panel. The pump motor requires its own 12V battery, power source, or solar panel.

 

 

Soil moisture sensor

There are two different kinds of soil moisture sensors on the market: contact sensors and non-contact sensors. In order to detect the electrical conductivity, a contact soil sensor (as seen in Fig. 3) is employed in this study.

 

An analogue output from the moisture sensor may be readily interfaced with Arduino. Two sensors can be attached to the Arduino board's analogue pins A0 and A1 in this project. Each sensor has four pins accessible for connecting to the Arduino board: Vcc, Gnd, Ao, and Do. Digital output pin (Do) isn't utilised in this case. The Arduino board is attached to digital pins 3 and 9, respectively, to operate the water pump and servo motor.In other words, pin 9 on the Arduino board is linked to the servo motor signal control pin.

 

The program in Arduino reads the humidity value from the sensor every 20 seconds. If the value reaches the threshold value, the program does the following three things:

 

1- This servo drives the motor horn with the water pipe mounted on it to the potted plant whose moisture level is below the predetermined/threshold level.

2- It starts the motor pump to supply water to the plant for a certain period and then turns off the water pump (see Figure 4).

3- This servo drives the motor horn back to its initial position.

Software program

       

        Soil moisture sensor (contact type)

Motor pump

Actual-size PCB layout of the circuit

The programme is written in the Arduino programming language. The code is clearly written and well commented. Compile the Autowatering. ino code and upload it to the microcontroller using the Arduino IDE version 1.

 

The sensor will automatically calibrate once it is placed in the soil, and the threshold value will be shown on the serial monitor in the Arduino. Serial debugging is available in this program. Comment if you don't want to use a serial monitor.

 

 

Construction and testing

 

 

An actual-size, single-sided PCB layout of an automated plant watering system is shown in Figure 5, and its component layout is shown in Figure 6.

Fig. 6: Component layout of the PCB

Assemble components on a PCB to minimise errors. Alternatively, you can assemble them on a breadboard, an Arduino prototyping shield, or a general-purpose PCB. Upload the code to the Arduino UNO board and install the sensor in the soil of the plants. Do not submerge the sensor completely into the soil.

Fig. 7: Installing water pump in the container

Install the pump in a water container (see picture 7) that can hold a few litres of water. Attach the water pipe to the servo motor horn as shown in picture 8.

 

Before turning on the circuit, you need to take into account the following macro definitions in the code:

 

1️⃣Changing the angle of rotation of the servo horn towards the first pot and the second pot. The default values ​​are 70 degrees and 145 degrees.

2️⃣Changing the watering schedule based on the pot's size. Five and eight seconds are the default settings.

3️⃣Modify the threshold value to suit your needs. The 600 value is the default.

 

Place the flower pots where the pipe from the servo motor horn can easily reach them. When the humidity level drops below 600, the servo horn rotates at a 70 degree angle. That is, after the servo motor horn moves 70 degrees towards the first pot, the motor pump will be on for five seconds and then automatically shut off. Then, the servo returns to its original position. Similarly, if you are using the second sensor, the servo motor horn will be driven to 145 degrees in the second largest pot, the motor pump will be on for eight seconds and then automatically shut off. The servo returns to its original position.

 

 

Further application

 

Using the Arduino UNO board, you can water up to six different potted plants. By adding a few more lines to the code, you can water even more plants by using the Arduino Mega 2560 board, which has more analogue input pins.

You can also add an Ethernet or Wi-Fi shield and use the Twitter library, which will tweet on behalf of your plants to send messages like: "I need water," "tank is empty," "refill tank," "water," and so on.

A 16x2 LCD can be added to indicate the humidity level.

You can also enable the circuit to refill the tank after a few days, depending on the volume of the tank.