Sometimes you just need a wristwatch, and sometimes you come across a bunch of super-sweet retro LED displays pulled from old calculators. I mean, what else am I going to do with my time?
Background
Back in late 2009 my roommate was heckling me about never finishing my projects. At the same time, technologically absurd wristwatches were all the rage in the Maker community. Nixie Tubes, high-res OLEDs and discrete LEDs were the thing to have, battery life be damned.
I wanted a slightly different aesthetic and found exactly what I was looking for.
What it does
- Displays time in a variety of formats
What it’s made of
- PIC24FJ32GA104 microcontroller
- Weird old-stock 14-digit LED display from Anchor Electronics
- A bunch of support components
- Custom PCB designed in EAGLE and fabricated at PCBExpress
- Firmware written in C using MPLABX, compiled by XC16 and loaded using an ICD3
Theory of operation
Push the “Display” button and the time glows at you for 3 full seconds.
That’s all the tutorial I have for now – you can read through main.c to see what the setting fields mean.
Conclusion
The watch worked well. One thing to note is the LED segments aren’t very bright when used with a coin-cell battery because those ultra long-life batteries can only source about 2mA sustained and 10mA pulsed. Attach a reasonable battery and things will lighten up.