Circuit Documentation

Summary

The circuit is designed to monitor environmental parameters such as temperature, humidity, CO2 levels, and soil moisture. It utilizes an Arduino Mega 2560 as the central microcontroller to read data from DHT22 sensors, MQ135 sensors, and a capacitive soil moisture sensor. The data is displayed on both an LCD and an OLED display. A rotary encoder allows the user to switch between different data pages on the OLED display. The circuit also includes a 4-channel relay module to control external devices and an RGB LED matrix for visual alerts. An SD card module is used for data logging purposes.

Component List

Arduino Mega 2560

• Microcontroller board based on the ATmega2560
• Provides numerous digital input/output pins, analog inputs, and various communication interfaces

4 Channel Relay Module

• Module with 4 electromechanical relays
• Each relay has normally open (N.O.), common (COM), and normally closed (N.C.) terminals

OLED 128x64 I2C Monochrome Display

• Small display for showing graphical and textual information
• Uses I2C communication protocol

LCD I2C Display

• Alphanumeric liquid crystal display with I2C interface
• Displays characters and numbers

Rotary Encoder (x2)

• Input device that provides rotational feedback
• Includes pins for ground, power, switch, and two data outputs

MQ135 Gas Sensor (x2)

• Sensor for detecting a wide range of gases, including CO2
• Provides both analog and digital outputs

DFRobot Capacitive Soil Moisture Sensor (V1.0)

• Sensor for measuring the moisture content in soil
• Outputs an analog signal

RTC DS1307

• Real-time clock module for keeping track of the current time and date
• Uses I2C communication protocol

DHT22 Temperature and Humidity Sensor (x2)

• Sensor for measuring ambient temperature and humidity
• Provides a digital signal output

WS2812 RGB LED Matrix 1x8

• Strip of 8 individually addressable RGB LEDs
• Controlled via a single data line

2cm x 8cm PCB

• Generic printed circuit board for prototyping

SD Card Module

• Module for reading and writing to SD cards
• Uses SPI communication protocol

Wiring Details

Arduino Mega 2560

• 3V3 to SD Card Module +3.3V
• 5V to all components requiring 5V supply
• GND to all components requiring ground connection
• A0 to Soil Moisture Sensor A
• A1 to MQ135 Sensor A0
• A2 to MQ135 Sensor A0
• D21/SCL to I2C devices SCL (LCD, OLED, RTC)
• D20/SDA to I2C devices SDA (LCD, OLED, RTC)
• D17 PWM/RX2 to Relay Module IN 4
• D16 PWM/TX2 to Relay Module IN 3
• D15/RX3 to Relay Module IN 2
• D14/TX3 to Relay Module IN 1
• D5 PWM to Rotary Encoder CLK
• D6 PWM to Rotary Encoder DT
• D7 PWM to Rotary Encoder SW
• D9 PWM to Rotary Encoder CLK
• D10 PWM to Rotary Encoder DT
• D11 PWM to Rotary Encoder SW
• D12 PWM to RGB LED Matrix DIN
• D22 to DHT22 Sensor OUT
• D24 to DHT22 Sensor OUT
• D46 to SD Card Module CS
• D50 to SD Card Module MISO
• D51 to SD Card Module MOSI
• D52 to SD Card Module SCK

4 Channel Relay Module

• VCC+ to 5V supply
• VCC- (GND) to ground
• IN 1 to D14/TX3 on Arduino
• IN 2 to D15/RX3 on Arduino
• IN 3 to D16 PWM/TX2 on Arduino
• IN 4 to D17 PWM/RX2 on Arduino

OLED 128x64 I2C Monochrome Display

• VDD to 5V supply
• GND to ground
• SCK to D21/SCL on Arduino
• SDA to D20/SDA on Arduino

LCD I2C Display

• VCC to 5V supply
• GND to ground
• SDA to D20/SDA on Arduino
• SCL to D21/SCL on Arduino

Rotary Encoder (x2)

• GND to ground
• + to 5V supply
• SW to D7 PWM or D11 PWM on Arduino
• DT to D6 PWM or D10 PWM on Arduino
• CLK to D5 PWM or D9 PWM on Arduino

MQ135 Gas Sensor (x2)

• VCC to 5V supply
• GND to ground
• A0 to A1 or A2 on Arduino

DFRobot Capacitive Soil Moisture Sensor (V1.0)

• VCC to 5V supply
• GND to ground
• A to A0 on Arduino

RTC DS1307

• VCC to 5V supply
• GND to ground
• SDA to D20/SDA on Arduino
• SCL to D21/SCL on Arduino

DHT22 Temperature and Humidity Sensor (x2)

• VCC to 5V supply
• GND to ground
• OUT to D22 or D24 on Arduino

WS2812 RGB LED Matrix 1x8

• VCC to 5V supply
• GND to ground
• DIN to D12 PWM on Arduino

SD Card Module

• GND to ground
• +3.3V to 3V3 on Arduino
• +5V to 5V supply
• CS to D46 on Arduino
• MOSI to D51 on Arduino
• SCK to D52 on Arduino
• MISO to D50 on Arduino

Documented Code

/*
 * This Arduino Sketch reads data from DHT22 sensors for temperature and
 * humidity, MQ135 sensors for CO2 levels, and a soil moisture sensor. It
 * displays the data on an LCD and OLED screen. The LCD shows the date and
 * time, while the OLED cycles through pages displaying temperature, humidity,
 * CO2 levels, and soil moisture. A rotary encoder is used to switch between
 * the pages on the OLED display. The code also controls a relay module and an
 * RGB LED matrix based on specific conditions.
 */

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>
#include <DHT.h>
#include <RTClib.h>
#include <Adafruit_NeoPixel.h>
#include <SD.h>

#define DHTPIN0 22
#define DHTPIN1 24
#define DHTTYPE DHT22
#define MQ135PIN0 A2
#define MQ135PIN1 A1
#define SOILMOISTUREPIN A0
#define OLED_RESET -1
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define RELAY1 14
#define RELAY2 15
#define RGB_PIN 12
#define NUMPIXELS 8
#define SD_CS 46

DHT dht0(DHTPIN0, DHTTYPE);
DHT dht1(DHTPIN1, DHTTYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
RTC_DS1307 rtc;
Adafruit_NeoPixel pixels(NUMPIXELS, RGB_PIN, NEO_GRB + NEO_KHZ800);
File dataFile;

int page = 0;
const int totalPages = 4;
unsigned long previousMillis = 0;
const long interval = 20000;
bool relay2State = false;

void setup() {
  Wire.begin();
  lcd.begin();
  lcd.backlight();
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.display();
  delay(2000);
  display.clearDisplay();
  dht0.begin();
  dht1.begin();
  rtc.begin();
  pinMode(9, INPUT);
  pinMode(10, INPUT);
  pinMode(11, INPUT);
  pinMode(RELAY1