Arduino Alarm Clock using Ds3231 and I2C Lcd Display

Projects Programming
1

Hello, this is my first post in this forum, any forum actually, so I am very sorry If I make mistakes. I have a code for a school project but no matter how many times I modify the code, error messages still come up and I do not know how to fix them. Can someone please help me?

THE CODE IS:

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DS3231.h>

// Set the LCD address to 0x3F for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x3F, 16, 2);

DS3231 rtc; // Initialize DS3231 instance

int Hour;
int Min;
int pset = 8; // Pushbutton for setting alarm
int phour = 9; // Pushbutton for hour
int pmin = 10; // Pushbutton for minutes
int pexit = 11; // Pushbutton for exit of set alarm
int buzzer = 6;
int h = 0; // Initialize alarm hour
int m = 0; // Initialize alarm minute
int buttonforset = 0; // Pushbutton state for setting alarm
int buttonforhour = 0; // Pushbutton state for hour
int buttonformin = 0; // Pushbutton state for minutes
int buttonforexit = 0; // Pushbutton for exit of set alarm
int activate = 0;

void setup() {
  pinMode(pset, INPUT);
  pinMode(phour, INPUT);
  pinMode(pmin, INPUT);
  pinMode(pexit, INPUT);
  pinMode(buzzer, OUTPUT);

  // Initialize LCD
  lcd.begin();
  lcd.backlight();

  // Set the RTC date and time if necessary
  rtc.setClockMode(false); // Use 24-hour mode
  if (rtc.getYear() == 0) {
    rtc.setYear(25);      // Year (last two digits)
    rtc.setMonth(1);      // Month
    rtc.setDate(17);      // Day
    rtc.setHour(4);       // Hour
    rtc.setMinute(51);    // Minute
    rtc.setSecond(30);    // Second
  }
}

void loop() {
  bool h12, PM_time, Century;
  Hour = rtc.getHour(h12, PM_time); // Retrieve hour
  Min = rtc.getMinute();           // Retrieve minute

  if (activate == 0) {
    lcd.setCursor(0, 0);
    lcd.print("Time: ");
    lcd.setCursor(6, 0);
    if (Hour < 10) lcd.print('0'); // Add leading zero
    lcd.print(Hour);
    lcd.print(":");
    if (Min < 10) lcd.print('0'); // Add leading zero
    lcd.print(Min);

    lcd.setCursor(0, 1);
    lcd.print("Date: ");
    lcd.setCursor(6, 1);
    lcd.print(2000 + rtc.getYear()); // Add 2000 to get the full year
    lcd.print("-");
    if (rtc.getMonth(Century) < 10) lcd.print('0'); // Add leading zero
    lcd.print(rtc.getMonth(Century));
    lcd.print("-");
    if (rtc.getDate() < 10) lcd.print('0'); // Add leading zero
    lcd.print(rtc.getDate());

    buttonforset = digitalRead(pset);
  }

  // Setting button pressed
  if (buttonforset == HIGH) {
    activate = 1;
    lcd.clear();
    delay(200);
  }

  while (activate == 1) {
    lcd.setCursor(0, 0);
    lcd.print("Set Alarm");
    lcd.setCursor(0, 1);
    lcd.print("Hour= ");
    lcd.setCursor(9, 1);
    lcd.print("Min= ");

    buttonforhour = digitalRead(phour); // Set hour for alarm
    if (buttonforhour == HIGH) {
      h++;
      if (h > 23) h = 0;
      lcd.setCursor(5, 1);
      lcd.print(h < 10 ? "0" : ""); // Add leading zero
      lcd.print(h);
      delay(200);
    }

    buttonformin = digitalRead(pmin); // Set minutes for alarm
    if (buttonformin == HIGH) {
      m++;
      if (m > 59) m = 0;
      lcd.setCursor(13, 1);
      lcd.print(m < 10 ? "0" : ""); // Add leading zero
      lcd.print(m);
      delay(200);
    }

    buttonforexit = digitalRead(pexit); // Exit from set alarm mode
    if (buttonforexit == HIGH) {
      activate = 0;
      lcd.clear();
      delay(200);
    }

    lcd.setCursor(5, 1);
    lcd.print(h < 10 ? "0" : ""); // Add leading zero
    lcd.print(h);
    lcd.setCursor(13, 1);
    lcd.print(m < 10 ? "0" : ""); // Add leading zero
    lcd.print(m);
  }

  // Check if it's time to trigger the alarm
  if (Hour == h && Min == m) {
    tone(buzzer, 400, 300); // Trigger buzzer for 300 ms
    delay(500); // Wait before checking again
  }
}

THE ERROR MESSAGES ARE:


C:\Users\romhe\AppData\Local\Temp\ccbs8WzA.ltrans0.ltrans.o: In function `global constructors keyed to 65535_0_sketch_jan17a.ino.cpp.o.1990':
<artificial>:(.text.startup+0x32): undefined reference to `LiquidCrystal_I2C::LiquidCrystal_I2C(unsigned char, unsigned char, unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\ccbs8WzA.ltrans0.ltrans.o: In function `setup':
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:33: undefined reference to `LiquidCrystal_I2C::begin()'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:34: undefined reference to `LiquidCrystal_I2C::backlight()'
C:\Users\romhe\AppData\Local\Temp\ccbs8WzA.ltrans0.ltrans.o: In function `loop':
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:54: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:56: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:63: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:65: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:80: undefined reference to `LiquidCrystal_I2C::clear()'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:85: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:87: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:89: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:96: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:106: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:115: undefined reference to `LiquidCrystal_I2C::clear()'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:119: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
C:\Users\romhe\AppData\Local\Temp\.arduinoIDE-unsaved2025017-13656-1o6e972.u2zu\sketch_jan17a/sketch_jan17a.ino:122: undefined reference to `LiquidCrystal_I2C::setCursor(unsigned char, unsigned char)'
collect2.exe: error: ld returned 1 exit status

exit status 1

Compilation error: exit status 1
2

How did you install the LiquidCrystal_I2C library? It would appear at first glance from those error messages that you've simply downloaded the header file rather than install the library in the usual fashion.

3

Maybe this is the problem, I went to a Github page and instead of downloading the whole zip I instead downloaded one file. Thanks! I will try this now.

4

No maybe about it. That is the problem.

Learn how to install additional libraries in the Arduino IDE 1.

1 Like
5

Thanks for the help.

6

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