Alarm Clock

Project 16 out of 18

Make a functional alarm clock that keeps accurate time, even when unplugged.

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Have you ever wondered how a computer keeps track of time even when it’s powered off? In this project, learn how computers keep track of time by building an Alarm Clock. Previously, in the Electronics Course, you used code to keep track of time. Now, you will use an RTC module instead. It has its own onboard circuitry to keep track of time more accurately and its own battery so it can continue to keep time even when the microcontroller isn’t on. You’ll assemble your hardware in several steps, first wiring the time module, adding the button and the LED, and then wiring the seven-segment display. After you put your hardware together, write the code for the Alarm Clock and learn how computers keep track of time. Learn about multiplexing and how it works to cut down on the number of pins it takes to control each LED on the seven-segment display. You now have an Alarm Clock you can use to wake up in the morning.

Milestones Unlocked



Programming (C++)

RTC Modules


Course Progression

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Lesson Preview

After you’ve finished making the project, complete these challenges that increase the functionality of your Alarm Clock:

  • Make the seven-segment display show text.
  • Make the seven-segment display illuminate in slow motion so you can see multiplexing in action.
  • Add the ability to have two different alarms at two different times.
  • Have the buzzer beep the same number of times as the hour that the clock is turning.

Electronics Course


18 Projects


Ages 12+


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