Project Documentation

Arduino UNO-Based Environmental Monitoring System with DHT11, BH1750, and GPS

Circuit Documentation

Summary

This circuit is designed to collect environmental data using various sensors and an Arduino UNO microcontroller. The sensors include a DHT11 for humidity and temperature, a BH1750 for light intensity, a capacitive soil moisture sensor, an NPK soil sensor, a pH meter, a rain sensor, and a GPS module. The Arduino UNO processes the data from these sensors and can be programmed to perform various tasks based on the sensor readings.

Component List

DHT11 Humidity and Temperature Sensor
- Description: Measures humidity and temperature.
- Pins: VDD, DATA, NULL, GND
Arduino UNO
- Description: Microcontroller board based on the ATmega328P.
- Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0
NPK Soil Sensor
- Description: Measures nitrogen, phosphorus, and potassium levels in soil.
- Pins: 12V DC, A, B, GND
PH Meter
- Description: Measures the pH level of a solution.
- Pins: Signal, VCC, GND
Capacitive Soil Moisture Sensor V1.2
- Description: Measures soil moisture levels.
- Pins: GND, VCC, AOUT
BH1750
- Description: Measures light intensity.
- Pins: VCC, GND, SCL, SDA, ADDR
NEO-6M (GPS Module)
- Description: Provides GPS data.
- Pins: GND, TX, RX, VCC
Resistor
- Description: 10k Ohm resistor used for pull-up.
- Pins: pin1, pin2
- Properties: Resistance: 10k Ohms
RAIN SENSOR
- Description: Detects rain.
- Pins: AO, DO, GRD, VCC

Wiring Details

DHT11 Humidity and Temperature Sensor

VDD connected to 5V on Arduino UNO
DATA connected to D2 on Arduino UNO via a 10k Ohm resistor
GND connected to GND on Arduino UNO

Arduino UNO

5V connected to VCC of various sensors
GND connected to GND of various sensors
Vin connected to 12V DC of NPK Soil Sensor
A0 connected to A of NPK Soil Sensor
A1 connected to Signal of PH Meter
A2 connected to AOUT of Capacitive Soil Moisture Sensor
A3 connected to AO of RAIN SENSOR
A4 connected to SDA of BH1750
A5 connected to SCL of BH1750
D2 connected to DATA of DHT11 via a 10k Ohm resistor
D3 connected to RX of NEO-6M (GPS Module)
D4 connected to TX of NEO-6M (GPS Module)
D7 connected to DO of RAIN SENSOR

NPK Soil Sensor

12V DC connected to Vin on Arduino UNO
A connected to A0 on Arduino UNO
B connected to GND on Arduino UNO
GND connected to GND on Arduino UNO

PH Meter

Signal connected to A1 on Arduino UNO
VCC connected to 5V on Arduino UNO
GND connected to GND on Arduino UNO

Capacitive Soil Moisture Sensor V1.2

GND connected to GND on Arduino UNO
VCC connected to 5V on Arduino UNO
AOUT connected to A2 on Arduino UNO

BH1750

VCC connected to 5V on Arduino UNO
GND connected to GND on Arduino UNO
SCL connected to A5 on Arduino UNO
SDA connected to A4 on Arduino UNO

NEO-6M (GPS Module)

GND connected to GND on Arduino UNO
TX connected to D4 on Arduino UNO
RX connected to D3 on Arduino UNO
VCC connected to 5V on Arduino UNO

Resistor

pin1 connected to 5V on Arduino UNO
pin2 connected to DATA of DHT11 and D2 on Arduino UNO

RAIN SENSOR

AO connected to A3 on Arduino UNO
DO connected to D7 on Arduino UNO
GRD connected to GND on Arduino UNO
VCC connected to 5V on Arduino UNO

Documented Code

/**
 * This example demonstrates how to collect temperature and humidity measurements
 * from the Adafruit DHT11 sensor. Measurements are printed out to the serial monitor.
 *
 * - Make sure to first install the following libraries through the Arduino Library Manager:
 *   - DHT Sensor Library (by Adafruit)
 *   - Adafruit Unified Sensor (by Adafruit)
 * - When you open the serial monitor to view measurements from the DHT11, make sure
 * that you select 9600 baud so that the serial monitor can receive data from the Arduino.
 *
 * This example was originally written by Adafruit Industries LLC.
 */

#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>

#define DHTPIN 2     // Digital pin connected to the DHT sensor 
// Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 --
// Pin 15 can work but DHT must be disconnected during program upload.

// Uncomment the type of sensor in use:
#define DHTTYPE    DHT11     // DHT 11
//#define DHTTYPE    DHT22     // DHT 22 (AM2302)
//#define DHTTYPE    DHT21     // DHT 21 (AM2301)

// See guide for details on sensor wiring and usage:
//   https://learn.adafruit.com/dht/overview

DHT_Unified dht(DHTPIN, DHTTYPE);

uint32_t delayMS;

void setup() {
  Serial.begin(9600);
  // Initialize device.
  dht.begin();
  Serial.println(F("DHTxx Unified Sensor Example"));
  // Print temperature sensor details.
  sensor_t sensor;
  dht.temperature().getSensor(&sensor);
  Serial.println(F("------------------------------------"));
  Serial.println(F("Temperature Sensor"));
  Serial.print  (F("Sensor Type: ")); Serial.println(sensor.name);
  Serial.print  (F("Driver Ver:  ")); Serial.println(sensor.version);
  Serial.print  (F("Unique ID:   ")); Serial.println(sensor.sensor_id);
  Serial.print  (F("Max Value:   ")); Serial.print(sensor.max_value); Serial.println(F("°C"));
  Serial.print  (F("Min Value:   ")); Serial.print(sensor.min_value); Serial.println(F("°C"));
  Serial.print  (F("Resolution:  ")); Serial.print(sensor.resolution); Serial.println(F("°C"));
  Serial.println(F("------------------------------------"));
  // Print humidity sensor details.
  dht.humidity().getSensor(&sensor);
  Serial.println(F("Humidity Sensor"));
  Serial.print  (F("Sensor Type: ")); Serial.println(sensor.name);
  Serial.print  (F("Driver Ver:  ")); Serial.println(sensor.version);
  Serial.print  (F("Unique ID:   ")); Serial.println(sensor.sensor_id);
  Serial.print  (F("Max Value:   ")); Serial.print(sensor.max_value); Serial.println(F("%"));
  Serial.print  (F("Min Value:   ")); Serial.print(sensor.min_value); Serial.println(F("%"));
  Serial.print  (F("Resolution:  ")); Serial.print(sensor.resolution); Serial.println(F("%"));
  Serial.println(F("------------------------------------"));
  // Set delay between sensor readings based on sensor details.
  delayMS = sensor.min_delay / 1000;
}

void loop() {
  // Delay between measurements.
  delay(delayMS);
  // Get temperature event and print its value.
  sensors_event_t event;
  dht.temperature().getEvent(&event);
  if (isnan(event.temperature)) {
    Serial.println(F("Error reading temperature!"));
  }
  else {
    Serial.print(F("Temperature: "));