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+ |
You can also buy them separately from the links below.
COMPONENT INTRODUCTION |
PURCHASE LINK |
---|---|
- |
|
- |
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
The data streams created in the previous projects need to be saved, and they will be used in this project as well.
For recording soil moisture, create another Datastream of type Virtual Pin on the Datastream page. Set DATA TYPE to
Integer
and MIN and MAX to0
and1024
.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.![]()
Replace the
Template ID
,Device Name
, andAuth Token
with your own. You also need to enter thessid
andpassword
of the WiFi you are using. For detailed tutorials, please refer to 1.4 Connecting the R3 board to Blynk.After selecting the correct board and port, click the Upoad button.
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.
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.
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);
}