System to Monitor Parameters of Your Plants

Introduction: System to Monitor Parameters of Your Plants

How to monitor parameters of your cactuses with the help Android smartphone.

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Step 1: What You'll Need

  • Arduino MEGA 2560 R3 (or any other, for example, Arduino Uno or Nano)
  • Soil humidity sensor for Arduino SMM038
  • Temperature and humidity sensor DHT11 (Aosong)
  • Resistor 10 kOhm; 0,25W; 5% (x2)
  • Printing circuit breadboard
  • Some case
  • CABLE-403/3.5 / socket 3,5 stereo & jack 3,5 stereo (x2)
  • Jumper wires (x4)
  • OTG cable

Tools: soldering iron + solder.

Step 2: Scheme & Soldering

On the picture you can see how to connect both of sensors with the help of a solderless breadboard.

Soil humidity sensor connected via a voltage divider circuit with resistor to 10kOhm as a permanent resistance. The sensor produces an analog signal and connected to the Arduino's A0 pin.

Temperature and humidity sensor connects with three contacts, the fourth is not used. It also requires 10 kOhm of resistance. The output of a the sensor is a digital signal.

Two jacks are soldered to the breadboard and two connectors are soldered to the cable. You can connect and disconnect sensors at any time.

Step 3: Sketch for Arduino

#include "DHT.h"
#define DHTPIN 30

int sensorPin = A0;

unsigned int sensorValue = 0;

#define DHTTYPE DHT11


void setup() {




void loop() {

float h = dht.readHumidity();

float t = dht.readTemperature();

sensorValue = analogRead(sensorPin);

if (isnan(t) || isnan(h) || h == 0) {


} else {

Serial.print("Humidity: ");



Serial.print("Temperature: ");


Serial.print(" *C\n");


Serial.print("Soil humidity: ");

Serial.print(float(sensorValue)/1024*100, 0);




Step 4: Downloading App for Android & Finish

I choose app called UsbTerminal. All settings are pictured. Baud rate in Arduino sketch should take the same value.

To get started, you need only to connect the OTG cable to your smartphone. You can see my working device on the photo.

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    3 Discussions


    4 years ago

    you can try to use ESP8266 to connect between arduino and your cellphone.that is convenienter than OTG cable


    Reply 4 years ago

    Thanks for reading and your comment :)