Tag Archives: watch

MatriLED Watch

This is a full 4,096 color 8×8 LED matrix based wristwatch with software-driven 4-bit PWM for each channel at 60 full PWM sweeps per second.

Background

I wanted to see how much performance I could squeeze out of the then-newly released PIC16F1 series of MCUs.

Video of time display

What it does

  • Displays time in a totally tubular way.

What it’s made of

Theory of operation

Press a button and the time shows up for three full seconds before putting the MCU to sleep. With the PWM blazing away at 60 full refreshes per second, there remains 50% CPU time available to do work. Pretty amazing for a ~$0.75 part. How time is represented:

  • Current second: fading yellow pixel, going from upper-left to lower right.
  • Current minutes (units): two-pixel wide blue column on far right. 0-8 are shown as pixels emanating from top as zero and bottom as 8. 9 is shown as a red pixel at the bottom.
  • Current minutes (tens):  two-pixel wide blue column on middle right.
  • Current hours (units):  two-pixel wide blue column on middle left.
  • Current hours (tens):  two-pixel wide blue column on far left.

Conclusion

Yuuuuup

Seven Segment Watch

Sometimes you just need a wristwatch, and sometimes you come across a bunch of super-sweet retro LED displays pulled from calculators of yore. 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

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.