Tilt Touch Time

A tilt and touch activated wristwatch using a "retro" style bubble 7 segment display.

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As with many projects this one started with me finding a cool component that i wanted to use, in this case a retro style bubble 7 segment display. Being somewhat of a watch enthusiast I decided to design yet another wristwatch.

Drawing from the experience gained from my last watch project ("A watch") I decided to use the same kind of tilt switch to activate the display but also adding a capacitive touch button which will enable me to hopefully add more functions such as a stopwatch and an easy way to set time. Another upgrade from the old design will be the new display making it much easier to tell time at a glance.

Since one of the requirement for the Hackaday contest is that the device is “connected” I am trying to figure out a way to sync the watches time to a PC/smartphone with the help of a photodiode an an optical flashing screen system.

More info will be available as the project develops

The source code, schematics, PCB files and 3D cad files for the case will all be released under an open source license as soon as the are done. 

Entry Video: 

System overview:

The two main components for the watch are the ATtiny2313 microcontroller and the time syncing app on a smart phone/PC. The watch will have the ability to sync it's time to the time of a smart phone/PC, enabling you to easily set the correct time on the watch. The one way communication between the phone/PC and the microcontroller will be done trough an optical system.


Time Syncing:

The optical communication is works by flashing the screen of the smart phone/PC sending 1 and 0 to the watch. The watch will pick up the signals with the help of a phototransistor and translating the flashes back to binary numbers and setting the time of the watch.

Tilt sensing:

To save power the Bubble display is turned off when it is not being used. The normal way a LED watch works is that you press a button to turn on the screen and show you the time but i feel that this is not a very practical since it is a two hand operation to just check the time. My solution to the problem is to have a tilt switch which when you tilt your wrist to check the time will automatically turn on the screen for you.

Touch sensing:

To be able to navigate trough the different functions of the watch I need a button of some sort. Since I didn't want a button sticking trough the case so I opted for a capacitive "button" instead. The capacitive sensing will be done by one of Atmels Qtouch ICs.

Below you can see an overview of the different parts of the project will communicate with each other.

  • Summer has come in the way

    askoog8908/17/2014 at 21:01 0 comments

    The project has been on hold for the last couple off week because off: Summer. The weather has been to good to bee sitting inside hacking on the project. But with the dead line coming up I better get started again.

    I have soldered together the prototype PCB and gotten the display and tilt sensor working with out any problems, the touch sensor is still acting up and needs some more TLC before it is ready for prime time. I also realized that syncing the time to the PC with help of the touch sensor probably isn’t a good idea, so I will be changing over to an optical system. I have one GPIO left on the avr where I will add a photodiode/transistor. The photodiode will be held against the computer screen where a Python script will send the current time by flashing the screen. This way of communication also has the advantage of also working with smartphones and tables.

  • Solder Time

    askoog8906/24/2014 at 20:32 0 comments

    The PCBs and components have arrived time to heat up the soldering iron!

  • Designing the case

    askoog8906/17/2014 at 21:41 0 comments

    I'm still waiting for the PCB to arrive so in the mean time I have started designing the case for the watch. I started off using openSCAD as my 3D CAD software since I have used it before and it is open source. But after a while I got frustrated with having to descried the design in code and started using Designspark Mechanical instead, a great free (but not open source) piece of software. 

     Watch Case V1

  • PCB and Component choices

    askoog8906/02/2014 at 21:14 0 comments

    I sent my PCB to the manufacture ( and it has already added it to a panel :-) hopefully I will have the PCBs at the end of the month. The only thing I forgot was to add a way to program the microcontroller... But that can be solved by soldering the programing wires directly to the pins.

    When it comes the components I tried to choose packages that didn’t have super extreme pitch but still keeping them surface mount to keep the size of the PCB to a size that would fit on a wrist. For the microcontroller I chose the ATTiny2313 in a SO-20 package mostly because I have used allot of Atmels microcontroller in other projects but also because Atmel seem to have a large support in the OSH/maker/hobby hacker community. For the capacitive touch sensing I chose a IC from atmels Qtouch line, the reason for choosing to go the IC rout instead of having the microcontroller do the sensing is simply that this seemed like a simpler and faster way to get up and running.

    The other components are 0603 resistors and capacitors a crystal oscillator and a tilt switch.

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mclien wrote 08/20/2014 at 16:01 point
I still can revoce the fazination I experienced, when I first looked at those LED displays of the pocket calculaters back in the 70th. Like that.
Perhaps we can join some forces whil the projects go on.

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askoog89 wrote 08/20/2014 at 22:21 point
Sounds like a good idea :-) I like the case design of your watch, how are you going to manufacture it?

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Adam Fabio wrote 06/14/2014 at 06:28 point
Great watch project! I love those bubble LEDs. Careful on the long term stability with those ATtinys - they can drift a bit. Don't forget to link in your code and schematics - being more open goes a long way.

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