Quick Dual Timezone Clock Design

Posted by mitch on January 17, 2012

I have long wanted a dual timezone clock for my desk but I never found one that I liked. Most of the multi-timezone clocks on the market are for 3 or 4 timezones and are gaudy analog displays or ultra utilitarian digital displays. Why not build one using an Arduino board as the base? This would enable a number of integration opportunities with Internet services.

I’m planning on having two screens on the clock, each of them 128×64 pixel monochrome displays. Driving one of these screens requires a significant number of I/O lines, so this design will benefit from using an Arduino Mega board, though I haven’t yet confirmed that the Mega has enough lines without some type of mux.

The model above shows an approximate mockup that I threw together while flying earlier today. The clock is about a 2×2.5×7″ rectangular prism with a triangular subtraction so that the screens can be tilted. I suspect the length can be shrunk to 6″ or less; there’s a lot of empty space in the above model. The Ethernet RJ45 and power jacks are moved from the Arduino boards to a separate board so that the main boards can be mounted vertically but the wires are still on the back of the clock.

I have a few software features in mind:

  1. NTP sync on power-on and thereafter syncing once per day. This has the obvious advantage of never having to set the clock and also enables using a cheaper real-time clock chip with a few seconds of drift per day.
  2. The above requires Ethernet. The Arduino Ethernet shield gets the job done.
  3. A simple web interface to configure the timezones and perhaps zip codes so that some weather information can be displayed for each location.
  4. A button on the back of the clock to show the DHCP-collected IP address.
  5. Perhaps a bit of integration with a calendar feed to show upcoming events on the calendar. This will likely require some kind of middleware that the clock communicates with. I am not sure I will take it this far.

PoE would be a cool addition but I’m not sure I want to mess with it for this project.

I’ll post again when I have more than vaporware. I ordered the LCD screens this weekend.