This circuit is designed to interface an Arduino UNO with an LCD I2C Display and a 4-channel 5V relay module. The LCD display is used to show a welcome message and the frequency of a square wave generated by the Arduino, which is also used to control the relays. The relays can be activated by digital signals from the Arduino to control external devices. The LCD communicates with the Arduino over the I2C protocol, while the relay module is controlled through digital output pins.
/*
* This Arduino Sketch initializes an I2C LCD display and controls a 4-channel
* relay module. The LCD displays a welcome message and then continuously
* updates to show the frequency of a square wave generated on one of the
* relay control pins. The relays can be controlled via digital pins D3, D4,
* D5, and D6.
*/
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
// Initialize the LCD with I2C address 0x27 and 16x2 display
LiquidCrystal_I2C lcd(0x27, 16, 2);
// Relay control pins
const int relay1 = 6;
const int relay2 = 5;
const int relay3 = 4;
const int relay4 = 3;
// Frequency measurement variables
unsigned long previousMillis = 0;
const long interval = 1000; // Interval for frequency calculation (1 second)
int frequency = 0;
void setup() {
// Initialize the LCD
lcd.begin(16, 2); // Corrected to include the number of columns and rows
lcd.backlight();
lcd.setCursor(0, 0);
lcd.print("Welcome!");
lcd.setCursor(0, 1);
lcd.print("Relay Control");
delay(2000); // Display welcome message for 2 seconds
// Set relay pins as outputs
pinMode(relay1, OUTPUT);
pinMode(relay2, OUTPUT);
pinMode(relay3, OUTPUT);
pinMode(relay4, OUTPUT);
// Initialize relays to off
digitalWrite(relay1, LOW);
digitalWrite(relay2, LOW);
digitalWrite(relay3, LOW);
digitalWrite(relay4, LOW);
}
void loop() {
unsigned long currentMillis = millis();
// Generate square wave on relay1 pin
digitalWrite(relay1, HIGH);
delay(500); // 500ms HIGH
digitalWrite(relay1, LOW);
delay(500); // 500ms LOW
// Calculate frequency every second
if (currentMillis - previousMillis >= interval) {
previousMillis = currentMillis;
frequency = 1; // Frequency is 1 Hz (1 cycle per second)
// Update LCD with frequency
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Frequency:");
lcd.setCursor(0, 1);
lcd.print(frequency);
lcd.print(" Hz");
}
}
This code initializes the LCD display and the relay module, then enters a loop where it generates a square wave on one of the relay control pins and updates the display with the frequency of this wave. The relays are controlled by digital pins D3 to D6 on the Arduino UNO.