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 input devices include a 4X4 Membrane Matrix Keypad for user input. The output devices consist of a buzzer, an LCD I2C Display, and three LEDs (red, green, and blue) with corresponding resistors for current limiting. The communication modules feature an RFID-RC522 reader for RFID tag reading and a SIM900A GSM module for cellular communication. A servo motor (SG90) is also included for actuation purposes.

Component List

Buzzer

• Pins: PIN, GND
• Description: An audio signaling device.

LCD I2C Display

• Pins: GND, VCC, SDA, SCL
• Description: A display module with I2C communication interface.

RFID-RC522

• Pins: SDA, SCK, MOSI, MISO, IRQ, GND, RST, 3.3V
• Description: An RFID reader module for reading RFID tags.

SG90 Servo Motor

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

4X4 Membrane Matrix Keypad

• Pins: R1, R2, R3, R4, C1, C2, C3, C4
• Description: A keypad with 16 buttons arranged in a 4x4 matrix.

Resistors (221 Ohms)

• Pins: pin1, pin2
• Description: Current-limiting resistors for LEDs.

LEDs: Two Pin (Red, Green, Blue)

• Pins: cathode, anode
• Description: Light Emitting Diodes of different colors.

Arduino Mega 2560

• Pins: Multiple digital and analog pins, power, and ground pins.
• Description: A microcontroller board based on the ATmega2560.

SIM900A

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

Wiring Details

Buzzer

• PIN connected to Arduino Mega 2560 (D10 PWM)
• GND connected through a resistor to Arduino Mega 2560 (GND)

LCD I2C Display

• GND connected to Arduino Mega 2560 (GND)
• 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 Arduino Mega 2560 (GND)
• 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 Arduino Mega 2560 (GND)

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)

• Each resistor has one pin connected to the cathode of an LED and the other pin connected to a common ground net.

LEDs: Two Pin (Red, Green, Blue)

• Cathode of each LED connected to a resistor (221 Ohms)
• Anode of the blue LED connected to SG90 Servo Motor (5V)

SIM900A

• RXD connected to Arduino Mega 2560 (D19/RX1)
• TXD connected to Arduino Mega 2560 (D18/TX1)
• GND connected to Arduino Mega 2560 (GND)

Documented Code

Arduino Mega 2560

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

}

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

}

4X4 Membrane Matrix Keypad

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 for keypad scanning and debouncing.)