Inspired by high-end wristwatches with retrograde hands, I decided t create a wall-mount version of an analog representation of the day and week for my office. I like to see the current date relative to the month’s or week’s end.
To implement retrograde hands, I choose step motors from car gauges. They consume very low power and are perfect for this application. For the electronics, I chose the microcontroller Microchip PIC18F24J50 because it has a built-in RTC module (to keep the time), enough pins to control the step motors, and an integrated USB port perfect for setup. Electronics powered by two AAA batteries. Because motors are activated only once in 24 hours, batteries will last several months. I added one LED with a light pipe near the center, which will start blinking when the batteries are too low and need to be replaced. The RTC module is programmed for 100 years, so every leap year will be adjusted automatically.
For construction, I got a cheap wall clock from Amazon. The clock module was removed, as well as the face plate. I designed an inner plate to mount my electronics and made a face plate from white-on-black acrylic with laser engraving. Hands 3D printed using black PETG filament.
To set the initial time (or update when the batteries were replaced), I created a simple MS Windows app. Using a USB cable, my device can be connected to a computer. The app will get system time and send it to the microprocessor.
The back side has an opening for a Micro-USB port and for batteries. The reset button will initiate USB communication when the cable is attached. The USB flash stick with the application is attached by Velcro, so the app will never be lost.
It looks great in my office.