Week 10 - Output Devices

LCD Display

For this project, I used an LCD display to show the maximum recorded value from the microphone sensor and the value of an RFID tag. The LCD display serves as an output device, providing a clear and real-time visualization of the data captured by the sensors.

Image source: lastminuteengineers.com

The LCD display is connected to the microcontroller via an I2C interface, which simplifies the wiring by using only two pins: SDA (Serial Data) and SCL (Serial Clock). This setup allows the microcontroller to send data to the LCD efficiently while leaving other GPIO pins available for additional components.

In this project, the microphone sensor captures sound levels, and the microcontroller processes the analog signal to determine the maximum recorded value. Simultaneously, an RFID reader is used to scan RFID tags, and the unique identifier (UID) of each tag is read. The microcontroller then sends both the maximum sound level and the RFID tag value to the LCD display for visualization.

The LCD display alternates between showing the maximum sound intensity and the RFID tag value, providing a user-friendly interface for monitoring both data points. This integration of input and output devices demonstrates the versatility of embedded systems in handling multiple tasks simultaneously.

By combining the microphone sensor, RFID reader, and LCD display, I was able to create a functional system that captures, processes, and displays data in real-time. This project highlights the importance of output devices in presenting information and enhancing the usability of embedded systems.

Code

Here is the code I used to read the RFID UID and microphone sound level, and display them on the LCD module:

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SPI.h>
#include <MFRC522.h>

// LCD setup
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 columns, 2 rows

// RFID setup
#define RST_PIN D3
#define SS_PIN D2
MFRC522 rfid(SS_PIN, RST_PIN);

// Microphone setup
int micPin = D1; // Analog pin connected to the microphone module
int micValue = 0;

void setup() {
  pinMode(micPin, INPUT);
  // Initialize LCD
  lcd.init();
  lcd.init();
  lcd.backlight();
  lcd.print("Initializing...");

  // Initialize RFID
  SPI.begin();
  rfid.PCD_Init();

  // Initialize Serial
  Serial.begin(9600);
  lcd.clear();
  lcd.print("Ready");
  delay(1000);
}

void loop() {
  // Read microphone value
  micValue = analogRead(micPin);

  // Display microphone value on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Mic Value:");
  lcd.setCursor(0, 1);
  lcd.print(micValue);
  delay(500);

  // Check for RFID card
  if (rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial()) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("RFID UID:");
  lcd.setCursor(0, 1);

  // Print UID to LCD
  for (byte i = 0; i < rfid.uid.size; i++) {
    lcd.print(rfid.uid.uidByte[i] < 0x10 ? "0" : "");
    lcd.print(rfid.uid.uidByte[i], HEX);
    if (i != rfid.uid.size - 1) lcd.print(":");
  }
  delay(3000);

  // Halt RFID card
  rfid.PICC_HaltA();
  }
}
              

This code initializes the LCD, RFID module, and microphone. It reads the microphone's analog value and displays it on the LCD. When an RFID card is detected, its UID is displayed on the LCD as well.

By running this code, I was able to observe both the microphone's sound levels and the RFID UID in real-time on the LCD module.