[ssh16] had seen some fancy wristwatches with retrograde hands. Wanting to do something similar of their own, they set about creating an analog wall calendar that displays the date and the day of the week.

The build uses a pair of stepper motors to control the hands, a simple choice for accurate and reliable motion control. A Microchip PIC18F24J50 serves as the brains of the operation, chosen for its built-in RTC module and the fact that it has plenty of IO for controlling stepper motors. The built-in RTC is programmed with calendar information for the next 100 years, so there is no need to adjust the clock for leap years on the regular. The top hand of the wall calendar is driven in an arc to show days of the month, from 1 to 31. The bottom hand similarly steps through the 7 days of the week. If you’re unfamiliar with the concept of retrograde hands, they’re simply hands that sweep in an arc instead of moving in a whole continuous circle.

Hackers do love a good clock build, even if this one doesn’t specifically tell the time itself. If you’ve whipped up your own nifty timepiece, know that we’d love to see its fine face on the tipsline!