Circuit Documentation

Summary

This circuit integrates a variety of components including microcontrollers, sensors, actuators, and an LCD display to form a complex system capable of sensing, processing, and responding to environmental inputs. The Arduino UNO and Arduino Nano serve as the central processing units, interfacing with an RFID module, gas sensor, IR sensor, piezo buzzers, and an LCD display. User inputs are captured through pushbuttons, and a potentiometer is used for adjustable settings. The circuit is powered by a 3.3V and 5V supply from the Arduino UNO, with additional power connections to a relay and a DFPlayer Mini module. Actuation is achieved through a DC motor controlled by relays. The circuit's functionality is determined by the embedded code running on the Arduino platforms.

Component List

• Arduino Nano: A compact microcontroller board based on the ATmega328P, featuring digital and analog I/O pins.
• LCD Display (16 pin): A 16x2 character LCD display for user interface and data display.
• Trimmer Potentiometer: A variable resistor with a 10k Ohm value for adjusting voltage levels.
• Piezo Buzzer: An electronic device that emits a tone when voltage is applied.
• r307: A fingerprint scanner module for biometric input.
• RTC Module: A real-time clock module for timekeeping.
• Pushbutton: A momentary switch used for user input.
• Arduino UNO: A microcontroller board based on the ATmega328P, with a variety of digital and analog I/O pins.
• RFID-RC522: An RFID reader/writer module for contactless communication.
• 5V Relay: An electromechanical switch used for controlling high power devices.
• IR Sensor: An infrared sensor for detecting proximity or measuring distance.
• MQ-4: A gas sensor for detecting methane and natural gas concentrations.
• Rocker Switch: A switch for toggling circuit power or control signals.
• 18650 Li-ion Battery x 2: A power source consisting of two lithium-ion batteries.
• DC Motor: An electric motor that runs on direct current (DC).
• DFPlayer Mini: A small and low-cost MP3 module for playing music files.

Wiring Details

Arduino Nano

• Digital Pins:
  • D2 to r307 TX
  • D3 to r307 RX
  • D4 to 5V Relay In
  • D5 to Arduino UNO A0
  • D6 to Piezo Buzzer pin 2
  • D7 to LCD Display DB7
  • D8 to LCD Display DB6
  • D9 to LCD Display DB5
  • D10 to LCD Display DB4
  • D11/MOSI to LCD Display E
  • D12/MISO to LCD Display RS
• Analog Pins:
  • A0 to Pushbutton Pin 3 (out)
  • A1 to Pushbutton Pin 3 (out)
  • A2 to Pushbutton Pin 3 (out)
  • A3 to Pushbutton Pin 3 (out)
  • A4 to RTC Module SDA
  • A5 to RTC Module SCL
• Power Pins:
  • 5V to LCD Display VDD, RTC Module VCC, r307 VCC
  • GND to various components including LCD Display VSS and Pushbuttons Pin 2 (in)
  • VIN to external power source

LCD Display (16 pin)

• Data Pins:
  • DB4 to Arduino Nano D10
  • DB5 to Arduino Nano D9
  • DB6 to Arduino Nano D8
  • DB7 to Arduino Nano D7
• Control Pins:
  • RS to Arduino Nano D12/MISO
  • E to Arduino Nano D11/MOSI
• Power Pins:
  • VDD to Arduino Nano 5V
  • VSS, A, R_W to GND
  • VO to Trimmer Potentiometer wiper

Trimmer Potentiometer

• Pins:
  • Leg1 to Arduino Nano 5V
  • Wiper to LCD Display VO
  • Leg2 to GND

Piezo Buzzer

• Pins:
  • Pin 1 to GND
  • Pin 2 to Arduino Nano D6 or Arduino UNO D2

r307

• Communication Pins:
  • TX to Arduino Nano D2
  • RX to Arduino Nano D3
• Power Pins:
  • VCC to Arduino Nano 5V
  • GND to GND

RTC Module

• Communication Pins:
  • SCL to Arduino Nano A5
  • SDA to Arduino Nano A4
• Power Pins:
  • VCC to Arduino Nano 5V
  • GND to Pushbuttons Pin 2 (in)

Pushbutton

• Pins:
  • Pin 2 (in) to GND
  • Pin 3 (out) to Arduino Nano A0, A1, A2, A3

Arduino UNO

• Digital Pins:
  • D0 to DFPlayer Mini TX
  • D1 to DFPlayer Mini RX
  • D2 to Piezo Buzzer pin 2
  • D3 to IR Sensor out
  • D5 to Rocker Switch 2
  • D6 to Arduino Nano D5
  • D7 to MQ-4 D0
  • D9 to RFID-RC522 RST
  • D10 to RFID-RC522 SDA
  • D11 to RFID-RC522 MOSI
  • D12 to RFID-RC522 MISO
  • D13 to RFID-RC522 SCK
• Analog Pins:
  • A0 to Arduino Nano D5
  • A1 to Arduino UNO D6
  • A2 to 5V Relay In
• Power Pins:
  • 3.3V to RFID-RC522 VCC (3.3V)
  • 5V to various components including 5V Relay VCC and DFPlayer Mini VCC
  • GND to various components including RFID-RC522 GND and Piezo Buzzer pin 1

RFID-RC522

• Communication Pins:
  • SCK to Arduino UNO D13
  • MISO to Arduino UNO D12
  • MOSI to Arduino UNO D11
  • SDA to Arduino UNO D10
  • RST to Arduino UNO D9
• Power Pins:
  • VCC (3.3V) to Arduino UNO 3.3V
  • GND to GND

5V Relay

• Control Pins:
  • In to Arduino UNO A2 or Arduino Nano D4
• Switch Pins:
  • Normally Open to DC Motor pin 1
  • Common terminal to 18650 Li-ion Battery x 2 +
• Power Pins:
  • VCC to Arduino UNO 5V
  • GND to GND

IR Sensor

• Pins:
  • Out to Arduino UNO D3
  • GND to GND
  • VCC to Arduino UNO 5V

MQ-4

• Pins:
  • D0 to Arduino UNO D7
  • GND to GND
  • VCC to Arduino UNO 5V

Rocker Switch

• Pins:
  • 1 to GND
  • 2 to Arduino UNO D5

18650 Li-ion Battery x 2

• Pins:
  • • to 5V Relay Common terminal
  • • to 5V Relay Common terminal

DC Motor

• Pins:
  • Pin 1 to 5V Relay Normally Open
  • Pin 2 to 5V Relay Normally Open

DFPlayer Mini

• Communication Pins:
  • RX to Arduino UNO D1
  • TX to Arduino UNO D0
• Power Pins:
  • VCC to Arduino UNO 5V
  • GND to GND

Documented Code

Arduino Nano Code

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

}

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

}

Arduino UNO Code

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

}

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

}

Note: The provided code for both the Arduino Nano and Arduino UNO is a template with empty setup and loop functions. The actual functionality needs to be implemented according to the requirements of the circuit's application.