Digital Wall Clock on PCB using AVR Microcontroller Atmega16 and DS3231 RTC

The Digital Wall Clock project is built around an ATmega16 AVR microcontroller, which acts as the central processing unit to manage timekeeping and display logic. Accurate time data is supplied by the DS3231 real-time clock IC, a precision RTC module that keeps track of hours, minutes, and seconds, communicating with the microcontroller via its integrated interface. Power regulation is handled by a 7805 voltage regulator paired with 1000uF and 10uF capacitors to step down and stabilize the input from the power supply adaptor, ensuring a steady 5V rail for the digital logic, while a 3V button cell acts as a backup power source to preserve time data during power outages. The visual interface consists of ten large, common anode 0.8-inch seven-segment displays. Because driving so many segments directly would require too many pins, the system uses multiplexing enabled by BC547 and BC557 transistors acting as switching elements, driven by current-limiting resistors (100 Ohm, 1k, and 10k). User interaction is provided through push buttons for setting the time and configuring options, and an onboard buzzer can be triggered for alarms or alerts. The entire circuit is housed on a custom PCB board connected via jumper wires and burgstips, and the system is programmed using the AVR GCC or Atmel Studio compiler.