Circuit Documentation

Summary

This document provides a detailed overview of a circuit designed to interface various components with an Arduino Mega 2560 microcontroller. The circuit includes input devices, output devices, and communication modules, which are interconnected through a series of electrical nets. The primary components include a buzzer, an LCD I2C display, an RFID-RC522 module, an SG90 servo motor, a 4x4 membrane matrix keypad, resistors, LEDs, and a SIM900A GSM module. The Arduino Mega 2560 serves as the central processing unit, controlling the various peripherals through its GPIO pins.

Component List

Buzzer

• Description: A simple piezoelectric buzzer for audio signaling.
• Pins: PIN, GND

LCD I2C Display

• Description: An LCD display with an I2C interface for visual output.
• Pins: GND, VCC, SDA, SCL

RFID-RC522

• Description: An RFID reader/writer module for contactless communication.
• Pins: SDA, SCK, MOSI, MISO, IRQ, GND, RST, 3.3V

SG90 Servo Motor

• Description: A small and lightweight servo motor for precise angular movement.
• Pins: PWM, 5V, GND

4X4 Membrane Matrix Keypad

• Description: A 16-button keypad for user input.
• Pins: R1, R2, R3, R4, C1, C2, C3, C4

Resistors (221 Ohms)

• Description: Three resistors used for current limiting or pull-up/down purposes.
• Pins: pin1, pin2

LEDs (Red, Green, Blue)

• Description: Three two-pin LEDs of different colors for visual signaling.
• Pins: cathode, anode

Arduino Mega 2560

• Description: A microcontroller board based on the ATmega2560, with numerous digital and analog I/O pins.
• Pins: Multiple GPIO pins including power, analog, and digital pins.

SIM900A GSM Module

• Description: A GSM/GPRS module for cellular communication.
• Pins: GND, DB9-3 (RXD), DB9-2 (TXD), 5V, 3VR, 5VR, 3VT, 5VT, VCC, Ring, RESTART, RESET, STATUS

Wiring Details

Buzzer

• PIN: Connected to Arduino Mega 2560 (D10 PWM)
• GND: Connected to common ground net

LCD I2C Display

• GND: Connected to common ground net
• VCC: Connected to Arduino Mega 2560 (5V)
• SDA: Connected to Arduino Mega 2560 (D20/SDA)
• SCL: Connected to Arduino Mega 2560 (D21/SCL)

RFID-RC522

• SDA: Connected to Arduino Mega 2560 (D53)
• SCK: Connected to Arduino Mega 2560 (D52)
• MOSI: Connected to Arduino Mega 2560 (D51)
• MISO: Connected to Arduino Mega 2560 (D50)
• IRQ: Not connected
• GND: Connected to common ground net
• RST: Connected to Arduino Mega 2560 (D9 PWM)
• 3.3V: Connected to Arduino Mega 2560 (3V3)

SG90 Servo Motor

• PWM: Connected to Arduino Mega 2560 (D8 PWM)
• 5V: Connected to LED: Two Pin (blue) anode
• GND: Connected to common ground net

4X4 Membrane Matrix Keypad

• R1: Connected to Arduino Mega 2560 (D22)
• R2: Connected to Arduino Mega 2560 (D24)
• R3: Connected to Arduino Mega 2560 (D26)
• R4: Connected to Arduino Mega 2560 (D28)
• C1: Connected to Arduino Mega 2560 (D30)
• C2: Connected to Arduino Mega 2560 (D32)
• C3: Connected to Arduino Mega 2560 (D34)
• C4: Connected to Arduino Mega 2560 (D36)

Resistors (221 Ohms)

• Resistor 1: One pin connected to buzzer GND, other pin connected to LED: Two Pin (red) cathode
• Resistor 2: One pin connected to buzzer GND, other pin connected to LED: Two Pin (green) cathode
• Resistor 3: One pin connected to buzzer GND, other pin connected to LED: Two Pin (blue) cathode

LEDs (Red, Green, Blue)

• Red LED: Anode connected to resistor 1, cathode connected to common ground net
• Green LED: Anode connected to resistor 2, cathode connected to common ground net
• Blue LED: Anode connected to SG90 servo motor 5V, cathode connected to resistor 3

SIM900A GSM Module

• GND: Connected to common ground net
• DB9-3 (RXD): Connected to Arduino Mega 2560 (D19/RX1)
• DB9-2 (TXD): Connected to Arduino Mega 2560 (D18/TX1)
• 5V: Not connected
• 3VR: Not connected
• 5VR: Not connected
• 3VT: Not connected
• 5VT: Not connected
• VCC: Not connected
• Ring: Not connected
• RESTART: Not connected
• RESET: Not connected
• STATUS: Not connected

Documented Code

Arduino Mega 2560 (Main Controller)

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

}

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

}

4X4 Membrane Matrix Keypad (Placeholder Code)

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

}

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

}

(Note: The code provided for the 4X4 Membrane Matrix Keypad is a placeholder and does not contain any functional code. It is expected that the user will implement the necessary code to handle keypad inputs.)