Circuit Documentation

Summary

The circuit in question is designed to monitor environmental parameters such as air quality, humidity, temperature, and pressure, and to control a stepper motor. It utilizes an Arduino UNO as the central microcontroller to interface with various sensors including the MQ135 Air Quality Sensor, DHT11 Humidity and Temperature Sensor, and an Industrial Pressure Sensor. The circuit also includes a SIM800L GSM module for communication purposes and an L298N motor driver to control a Nema 17 stepper motor. Power is supplied by a 12V battery and a 3.3V battery for different components.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Provides digital and analog I/O pins
• Includes power supply pins, communication interfaces, and a reset button

MQ135 Air Quality Sensor

• Gas sensor for detecting a wide range of gases, including NH3, NOx, alcohol, benzene, smoke, and CO2
• Provides both analog and digital outputs

Battery 12V

• Provides power to the circuit
• Typically used for high-power components or motors

DHT11 Humidity and Temperature Sensor

• Measures ambient humidity and temperature
• Provides a digital signal output

Nema 17 Stepper Motor (42-STH48)

• A stepper motor used for precise motion control
• Driven by the L298N motor driver

Industrial Pressure Sensor

• Measures pressure in an industrial environment
• Provides an analog signal output

L298N DC Motor Driver

• An H-bridge motor driver capable of driving a pair of DC motors or a stepper motor
• Provides several control inputs and power outputs for motor operation

SIM800L V2.0 GSM Module

• GSM/GPRS module for cellular communication
• Supports sending SMS and making voice calls

3.3V Battery

• Provides power to low-voltage components, such as the SIM800L GSM module

Sim800l GSM Module

• Another GSM module variant for cellular communication
• Similar to the SIM800L V2.0 but may have different pinouts or features

Wiring Details

Arduino UNO

• 5V connected to the 5V inputs of the Industrial Pressure Sensor, MQ135, L298N motor driver, and DHT11 sensor
• GND connected to the ground of the L298N motor driver, MQ135, Industrial Pressure Sensor, and DHT11 sensor
• A0 connected to A0 of MQ135
• A1 connected to Signal of Industrial Pressure Sensor
• A2 connected to DATA of DHT11 sensor
• D0 connected to SIM_TXD of SIM800L V2.0 GSM
• D1 connected to SIM.RXD of SIM800L V2.0 GSM
• D7 connected to DATA of DHT11 sensor
• D8 connected to IN1 of L298N motor driver
• D9 connected to IN2 of L298N motor driver
• D10 connected to IN3 of L298N motor driver
• D11 connected to IN4 of L298N motor driver

MQ135 Air Quality Sensor

• VCC connected to 5V of Arduino UNO
• GND connected to GND of Arduino UNO
• A0 connected to A0 of Arduino UNO

Battery 12V

• + connected to 12V of L298N motor driver
• - connected to GND of Arduino UNO

DHT11 Humidity and Temperature Sensor

• VDD connected to 5V of Arduino UNO
• DATA connected to D7 of Arduino UNO
• GND connected to GND of Arduino UNO

Nema 17 Stepper Motor (42-STH48)

• A1 Green connected to OUT1 of L298N motor driver
• A2 (black) connected to OUT2 of L298N motor driver
• B1 Blue connected to OUT3 of L298N motor driver
• B2 Red connected to OUT4 of L298N motor driver

Industrial Pressure Sensor

• DC+ connected to 5V of Arduino UNO
• DC- connected to GND of Arduino UNO
• Signal connected to A1 of Arduino UNO

L298N DC Motor Driver

• ENA and ENB connected to 5V of Arduino UNO
• 5V connected to 5V of Arduino UNO
• GND connected to GND of Arduino UNO
• IN1 connected to D8 of Arduino UNO
• IN2 connected to D9 of Arduino UNO
• IN3 connected to D10 of Arduino UNO
• IN4 connected to D11 of Arduino UNO
• OUT1 connected to A1 Green of Nema 17 motor
• OUT2 connected to A2 (black) of Nema 17 motor
• OUT3 connected to B1 Blue of Nema 17 motor
• OUT4 connected to B2 Red of Nema 17 motor
• 12V connected to + of 12V battery

SIM800L V2.0 GSM Module

• SIM_TXD connected to D0 of Arduino UNO
• SIM.RXD connected to D1 of Arduino UNO
• 5V/4V connected to + of 3.3V battery
• GND connected to - of 3.3V battery

3.3V Battery

• + connected to 5V/4V of SIM800L V2.0 GSM
• - connected to GND of SIM800L V2.0 GSM

Documented Code

#include <DHT.h>
#include <SoftwareSerial.h>

// Pin definitions
#define DHTPIN 7
#define DHTTYPE DHT11
#define MQ135_PIN A1
#define PRESSURE_SENSOR_PIN A2
#define MOTOR_IN1 8
#define MOTOR_IN2 9
#define MOTOR_IN3 10
#define MOTOR_IN4 11
#define SIM_TX 0
#define SIM_RX 1

// Initialize DHT sensor
DHT dht(DHTPIN, DHTTYPE);

// Initialize SoftwareSerial for SIM800L
SoftwareSerial sim800l(SIM_RX, SIM_TX);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  sim800l.begin(9600);

  // Initialize DHT sensor
  dht.begin();

  // Initialize motor driver pins
  pinMode(MOTOR_IN1, OUTPUT);
  pinMode(MOTOR_IN2, OUTPUT);
  pinMode(MOTOR_IN3, OUTPUT);
  pinMode(MOTOR_IN4, OUTPUT);

  // Initialize other sensors
  pinMode(MQ135_PIN, INPUT);
  pinMode(PRESSURE_SENSOR_PIN, INPUT);

  // Print initial messages
  Serial.println("System Initialized");
  sim800l.println("AT"); // Check if SIM800L is responding
}

void loop() {
  // Read DHT11 sensor
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  // Read MQ135 sensor
  int mq135Value = analogRead(MQ135_PIN);

  // Read Pressure sensor
  int pressureValue = analogRead(PRESSURE_SENSOR_PIN);

  // Print sensor values to Serial Monitor
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.print(" *C\t");
  Serial.print("MQ135: ");
  Serial.print(mq135Value);
  Serial.print("\t");
  Serial.print("Pressure: ");
  Serial.println(pressureValue);

  // Send data via SIM800L
  sim800l.print("Humidity: ");
  sim800l.print(humidity);
  sim800l.print(" %\t");
  sim800l.print("Temperature: ");
  sim800l.print(temperature);
  sim800l.print(" *C\t");
  sim800l.print("MQ135: ");
  sim800l.print(mq135Value);
  sim800l.print("\t");
  sim800l.print("Pressure: ");
  sim800l.println(pressureValue);

  // Control the stepper motor (example: rotate one step)
  digitalWrite(MOTOR_IN1, HIGH);
  digitalWrite(MOTOR_IN2, LOW);
  digitalWrite(MOTOR_IN3, HIGH);
  digitalWrite(MOTOR_IN4, LOW);
  delay(10);
  digitalWrite(MOTOR_IN1, LOW);
  digitalWrite(MOTOR_IN2, HIGH);
  digitalWrite(MOTOR_IN3, LOW);
  digitalWrite(MOTOR_IN4, HIGH);
  delay(10);

  // Wait for a second before next loop
  delay(1000);
}

This code initializes and reads from the