Circuit Documentation

Summary

This document provides a detailed overview of a circuit that includes a power supply, an Arduino UNO microcontroller, an LCD screen, a DHT11 temperature and humidity sensor, and an MQ-2 gas sensor. The circuit is designed to read environmental data and display it on the LCD screen.

Component List

SMPS_LRS-100-12

• Description: Switched-Mode Power Supply (SMPS) providing 12V output.
• Pins:
  • L: Live
  • N: Neutral
  • GND
  • -V
  • +V

Power 220V

• Description: 220V AC power source.
• Pins:
  • Hot wire
  • Neutral wire

LCD Screen 16x2 I2C

• Description: 16x2 character LCD screen with I2C interface.
• Pins:
  • SCL
  • SDA
  • VCC
  • 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

DHT11

• Description: Temperature and humidity sensor.
• Pins:
  • VCC
  • GND
  • Out

MQ-2

• Description: Gas sensor for detecting LPG, i-butane, propane, methane, alcohol, hydrogen, and smoke.
• Pins:
  • GND
  • VCC
  • ANALOG
  • Digital

PTC

• Description: Positive Temperature Coefficient (PTC) thermistor.
• Pins:
  • Neutral
  • Live

Wiring Details

SMPS_LRS-100-12

• L: Live connected to Power 220V Hot wire
• N: Neutral connected to Power 220V Neutral wire

Power 220V

• Hot wire connected to SMPS_LRS-100-12 L: Live
• Neutral wire connected to SMPS_LRS-100-12 N: Neutral

LCD Screen 16x2 I2C

• SCL connected to Arduino UNO SCL
• SDA connected to Arduino UNO SDA
• VCC connected to Arduino UNO 5V
• GND connected to Arduino UNO GND

Arduino UNO

• SCL connected to LCD Screen 16x2 I2C SCL
• SDA connected to LCD Screen 16x2 I2C SDA
• 5V connected to LCD Screen 16x2 I2C VCC, DHT11 VCC, MQ-2 VCC
• GND connected to LCD Screen 16x2 I2C GND, DHT11 GND, MQ-2 GND
• A0 connected to MQ-2 ANALOG
• D4 connected to DHT11 Out

DHT11

• VCC connected to Arduino UNO 5V
• GND connected to Arduino UNO GND
• Out connected to Arduino UNO D4

MQ-2

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

Documented Code

Arduino UNO Code (sketch.ino)

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

Additional Documentation (documentation.txt)