⏰ Digital Alarm Clock using 8051 Microcontroller

"Because waking up late shouldn't be a hardware problem."

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📌 Project Overview

This project is a Digital Alarm Clock built using the AT89C52 (8051) microcontroller. It features:

• ⌨️ 4x3 Keypad input for setting time and alarms
• 📟 16x2 LCD display to show current time and alarm status
• 🔔 Buzzer alert when alarm triggers
• 🕒 Real-time clock simulation using Timer 0 Designed as a simple embedded systems project, this serves as a beginner-friendly dive into 8051 microcontroller programming, LCD interfacing, keypad scanning, and GPIO control.

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🎯 Features

• ✅ Set current time (Hours:Minutes)
• ✅ Set alarm time via keypad
• ✅ Real-time clock with second updates
• ✅ Buzzer rings when time matches alarm
• ✅ LCD displays current time and alarm messages

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🔧 Hardware Requirements

• AT89C52 / 8051 Microcontroller
• 16x2 LCD
• 4x3 Matrix Keypad
• Buzzer
• Crystal Oscillator (typically 11.0592 MHz)
• Capacitors & Resistors for timing and pull-up
• Breadboard / PCB and power supply

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💡 How It Works

1. LCD Initialization – LCD is set in 8-bit mode and ready to display messages.
2. User Time Input – Keypad is used to input hours and minutes.
3. Alarm Setting – Alarm time is stored and monitored in real-time.
4. Timer 0 – Used to simulate 1-second delay (software polling).
5. Clock Display – Time is updated and displayed on LCD.
6. Alarm Trigger – If real-time matches the alarm, buzzer is activated.

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🧠 Code Highlights (alarm.c)

• lcdcmd() and lcddata() – Low-level LCD control
• keypad() and scankey() – Keypad scanning and input
• settime() – Set the current time
• checkconditions() – Alarm time input and logic
• clockdelay() – Simulated second-by-second update using Timer 0
• main() – Initializes system, sets time, and starts clock

🧾 You can find the full source code in alarm.c

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📦 Files Included

File Name	Description
alarm.c	Main C code for 8051 microcontroller
alarm.hex	Compiled HEX file for flashing
alarm.Uv2	Keil µVision project file
Digital Clock using 8051 Microcontroller.pdf	Project report with diagrams and explanation

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🛠️ To Run the Project

1. Load alarm.hex to your AT89C52 using a suitable programmer.
2. Connect the circuit as per the project schematic (see report).
3. Use the keypad to:
   • Set the current time
   • Set the alarm time
4. Watch time update on LCD.
5. Hear the buzzer ring when alarm time is reached!

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⚠️ Limitations & Improvements

Known Issues:

• Time resets incorrectly if it reaches 13:60:60.
• No debounce handling on keypad input.
• Timer is software-polled (not interrupt-based).

Future Enhancements:

• Use interrupt-driven Timer 0 for accurate timing.
• Add EEPROM support to save alarm time across resets.
• Include AM/PM format or 24-hour support.
• Add multiple alarms or snooze functionality.

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🧑‍💻 Author

Siddartha Reddy

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📜 License

This project is open-source and free to use under the MIT License.

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⭐ Show Some ❤️

If you found this project useful or learned something new, consider giving this repo a ⭐ and sharing it with your peers.