6. Plant Monitor

The purpose of this project is to create a smart watering system that detects the current temperature, humidity, intensity of light, and soil moisture and displays them on Blynk.

As soon as you turn on the Switch toggle in Blynk Cloud, the pump will start working and the plants will be hydrated.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
3 in 1 Starter Kit	380+	3 in 1 Starter Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
SunFounder R3 Board	BUY
Breadboard	BUY
ESP8266 Module	BUY
Jumper Wires	BUY
Resistor	BUY
Photoresistor	BUY
DHT11 Humiture Sensor	-
Soil Moisture Module	BUY
L298N Module	BUY
Centrifugal Pump	-

1. Build the Cirduit

Note

The ESP8266 module requires a high current to provide a stable operating environment, so make sure the 9V battery is plugged in.

2. Edit Dashboard

1. The data streams created in the previous projects need to be saved, and they will be used in this project as well.

2. For recording soil moisture, create another Datastream of type Virtual Pin on the Datastream page. Set DATA TYPE to Integer and MIN and MAX to 0 and 1024.

   

3. Now go to the Wed Dashboard page, drag 2 Label widgets and set their data streams to V4 and V5 respectively; drag 2 Gauge widgets and set their data streams to show V6 and V7 respectively; and finally drag a Switch widget and set its data stream to V0.

   

3. Run the Code

Open the 6.plant_monitoring.ino file under the path of 3in1-kit\iot_project\6.plant_monitoring, or copy this code into Arduino IDE.

Note

• The DHT sensor library is used here, you can install it from the Library Manager.

  

1. Replace the Template ID, Device Name, and Auth Token with your own. You also need to enter the ssid and password of the WiFi you are using. For detailed tutorials, please refer to 1.4 Connecting the R3 board to Blynk.

2. After selecting the correct board and port, click the Upoad button.

3. Open the Serial monitor(set baudrate to 115200) and wait for a prompt such as a successful connection to appear.

   

   Note

   If the message ESP is not responding appears when you connect, please follow these steps.

   • Make sure the 9V battery is plugged in.

   • Reset the ESP8266 module by connecting the pin RST to GND for 1 second, then unplug it.

   • Press the reset button on the R3 board.

   Sometimes, you may need to repeat the above operation 3-5 times, please be patient.

4. Back to the Blynk, you will see the current temperature, humidity, light intensity, and soil moisture. You can let the pump water the plants if necessary by clicking the Button Control widget.

   

5. If you want to use Blynk on mobile devices, please refer to How to use Blynk on mobile device?.

   

How it works?

This BLYNK_WRITE causes Blynk’s Switch widget to start the pump when it is ON and turn it off when it is OFF.

BLYNK_WRITE(V0)
{
    if(param.asInt()==1){
        digitalWrite(pumpA,HIGH);
    }else{
        digitalWrite(pumpA,LOW);
    }
}

These three functions are used to get the current environment temperature, humidity, light intensity and soil moisture.

int readMoisture(){
    return analogRead(moisturePin);
}

int readLight(){
    return analogRead(lightPin);
}

bool readDHT() {

    // Reading temperature or humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
    humidity = dht.readHumidity();
    // Read temperature as Celsius (the default)
    temperature = dht.readTemperature();

    // Check if any reads failed and exit early (to try again).
    if (isnan(humidity) || isnan(temperature)) {
        Serial.println("Failed to read from DHT sensor!");
        return false;
    }
    return true;
}

With the Blynk Timer, the ambient temperature, humidity, light intensity and soil moisture are obtained every second and sent to the data stream on the Blynk Cloud, from which the widgets display the data.

void myTimerEvent()
{
    bool chk = readDHT();
    int light = readLight();
    int moisture = readMoisture();
    if(chk){
        Blynk.virtualWrite(V4,humidity);
        Blynk.virtualWrite(V5,temperature);
    }
    Blynk.virtualWrite(V6,light);
    Blynk.virtualWrite(V7,moisture);
}