This clock counts down to retirement
For most people, the idea of retiring is a very exciting thought. Finally, after decades of hard work, you can clock out for the last time and spend the rest of your life relaxing and enjoying your leisure years. RdRnr318’s coworker updates her whiteboard every day to countdown the number of days until she gets to retire. To save Martha some effort and reduce the office’s marker budget, RdRnr318 built this “Nearly-Autonomous Retirement Countdown Display” to replace the whiteboard.
This device does exactly what it says on the tin: it shows a countdown timer with the number of days until Martha reaches her retirement. It also displays the countdown in seconds, minutes, and hours, so Martha can get granular with her retirement daydreams. This device needs no buttons for setting the time, because RdRnr318 programmed it specifically for Martha. Her retirement date is hardcoded and there is a real-time clock with a battery backup, so it can automatically calculate the countdown even after losing power.
An Arduino Uno board controls the device. It monitors the current time using a SparkFun DeadOn DS3234 RTC Breakout and displays the countdown on a simple 20×4 character LCD screen. Power comes from a wall wart or, in case of a power outage, a CR2032 battery backup. The case is a standard prefabricated enclosure box. The sketch is straightforward and pulls the current time from the RTC. It then subtracts that from Martha’s retirement date to get the remaining time. It even accounts for the differing number of days in each month and leap years!