Plant Monitor with Blynk¶

This project creates a plant monitoring demo system that detects the current temperature, humidity, light intensity, and soil moisture. The data is then displayed on Blynk along with suggestions based on the soil moisture levels.

1. Build the Circuit¶

Note

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

2. Configure Blynk¶

Note

If you are not familiar with Blynk, it is strongly recommended that you read these two tutorials first. Get Started with Blynk is a beginner’s guide for Blynk, which includes how to configure ESP8266 and register with Blynk. And Flame Alert System with Blynk is a simple example, but the description of the steps will be more detailed.

2.1 Create template¶

Firstly, we need to establish a template on Blynk. Create a “Plant Monitor” template.

2.2 Datastream¶

Create Datastreams of type Virtual Pin in the Datastream page receive data from esp8266 and uno r4 board.

Create Virtual Pin V0 according to the following diagram:

Set the name of the Virtual Pin V0 to temperature. Set the DATA TYPE to Double and MIN and MAX to -100 and 100. Set the UNITS to Celsius,℃.
Create Virtual Pin V1 according to the following diagram:

Set the name of the Virtual Pin V1 to humidity. Set the DATA TYPE to Double and MIN and MAX to 0 and 100. Set the UNITS to Percentage,%.
Create Virtual Pin V2 according to the following diagram:

Set the name of the Virtual Pin V2 to soilMoisture. Set the DATA TYPE to String.
Create Virtual Pin V3 according to the following diagram:

Set the name of the Virtual Pin V3 to LED. Set the DATA TYPE to Integer and MIN and MAX to 0 and 255.

2.3 Web Dashboard¶

We also need to configure the Web Dashboard to interact with the Plant monitor.

Configure the Web Dashboard according to the following diagram. We used widgets such as label, gauge, LED, and chart. Be sure to bind each widget to its corresponding virtual pin.

../_images/03-web_dashboard_1_shadow.png

2.4 Save template¶

At last, remember to save the template.

3. Run the Code¶

Open the 03-Plant_monitor.ino file under the path of ultimate-sensor-kit\iot_project\wifi\03-Plant_monitor, or copy this code into Arduino IDE.
Create a Blynk device using the “Plant Monitor” template. Then, replace the BLYNK_TEMPLATE_ID, BLYNK_TEMPLATE_NAME, and BLYNK_AUTH_TOKEN with your own.
```
#define BLYNK_TEMPLATE_ID "TMPxxxxxxx"
#define BLYNK_TEMPLATE_NAME "Plant Monitor"
#define BLYNK_AUTH_TOKEN "xxxxxxxxxxxxx"
```
You also need to enter the ssid and password of the WiFi you are using.
```
char ssid[] = "your_ssid";
char pass[] = "your_password";
```
After selecting the correct board and port, click the Upload 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 R4 board.
Sometimes, you may need to repeat the above operation 3-5 times, please be patient.

4. Code explanation¶

Initializing Libraries & Defining Constants:

This segment of code includes necessary libraries and defines certain constants like the Blynk template information and WiFi credentials.

#define BLYNK_TEMPLATE_ID "TMPLxxxxxxx"
#define BLYNK_TEMPLATE_NAME "Plant Monitor"
#define BLYNK_AUTH_TOKEN "xxxxxxxxxxx"
#define BLYNK_PRINT Serial
#include <ESP8266_Lib.h>
#include <BlynkSimpleShieldEsp8266.h>
char ssid[] = "your_ssid";
char pass[] = "your_password";
#include <SoftwareSerial.h>
SoftwareSerial EspSerial(2, 3);
#define ESP8266_BAUD 115200
ESP8266 wifi(&EspSerial);

Setting up the DHT Sensor:

The DHT sensor is initialized and relevant variables for storing temperature and humidity are defined.

#include <DHT.h>
#define DHTPIN 8
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);
float temperature;
float humidity;

Setting up the Soil Moisture Sensor:

Configuration for the soil moisture sensor. Thresholds for wet and dry conditions are defined.

You need to measure your own wetSoil and drySoil according to the your actual situation. Record the reading of Soil Moisture Module as drySoil when the soil is dry, and record the reading of Soil Moisture Module within a suitable range that you consider to be the most moist (going beyond this range would be too wet) as wetSoil.
```
#define wetSoil 320
#define drySoil 400
const int moistureSensorPin = A0;
int moisture;
String soilStatus;
```
Setting up the Timer:

A timer is configured which will dictate the frequency of data readings and updates.
```
BlynkTimer timer;
```
Initialization in Setup Function:

This section sets up the serial communication, configures the ESP8266 for WiFi, and begins the DHT sensor.
- We use timer.setInterval(5000L, myTimerEvent) to set the timer interval in setup(), here we set to execute the myTimerEvent() function every 5000ms. You can modify the first parameter of timer.setInterval(1000L, myTimerEvent) to change the interval between myTimerEvent executions.
```
void setup() {
   Serial.begin(115200);
   EspSerial.begin(ESP8266_BAUD);
   delay(10);
   Blynk.config(wifi, BLYNK_AUTH_TOKEN);
   Blynk.connectWiFi(ssid, pass);
   timer.setInterval(5000L, myTimerEvent);
   dht.begin();
}
```
loop() Function:

The main loop runs the Blynk process and timer.
```
void loop() {
   Blynk.run();
   timer.run();
}
```

sendData() Function:

This function reads values from the DHT sensor and soil moisture sensor, determines the soil’s status, and sends data to the Blynk app.

Use Blynk.virtualWrite(vPin, value) to send data to virtual pins on Blynk. Please refer to Blynk.virtualWrite() .
Use Blynk.setProperty(V3, "color", color) to set the color of LED on Blynk. More detail at Blynk - LED .

void sendData() {
   // (code for reading and determining values)
   Blynk.virtualWrite(V0, temperature);
   Blynk.virtualWrite(V1, humidity);
   Blynk.virtualWrite(V2, soilStatus);
   Blynk.virtualWrite(V3, 255);            // set blynk LED brightness
   Blynk.setProperty(V3, "color", color);  // set blynk LED color
}

Printing Data to Serial Monitor:

This function is useful for debugging and verifying the readings locally on the Arduino IDE’s serial monitor.
```
void printData() {
   // (code for printing values to serial monitor)
}
```

Reference