Programmable scientific calculator watch

When the band support on [David]‘s Casio CFX-400 Scientific Calculator Watch finally broke after 10 years of use, he found it almost impossible to find another watch with the same functionality. Like any good engineer, [David] decided to design a watch to meet his needs. The result of his endeavors was the µWatch, a programmable watch based on a PIC24 with both RPN and Algebraic calculation modes. The watch runs open source software and is expandable thanks to a serial port, an ICSP programming port, and a spot for an infrared LED on the board. On his site, [David] shows how he made the first µWatch and offers kits for anyone who wants to build their own. We’ve been told that the next batch of kits will be made available in 1-2 weeks and are expected to sell out fast.

[Thanks Tomesz]


  1. dan says:

    I have one of these, and it’s bitchin’.

    In addition to RPN, it even tells you what phase the moon is in!

  2. gabriel says:

    what’s this now? digg?

  3. Dave says:

    The next batch of watches are going to the assemblers today and should be available within the next two weeks.
    The current list of people signed up for next batch exceeds supply (if they all follow though and order one that is) – oops!


  4. jimmys says:


    Does Digg sell stuff too, now?

  5. nubie says:

    I’m geeking out, and to think I miss my Timex calculator watch (don’t let anyone know I used it on exams in 9th grade, there was an option to turn off the keypress “beep” ;) )

  6. nubie says:

    Ouch, for $99 I am sure I could get the Palm Pilot watch (And I will bet it is programmable with scientific functions :D ).

    This is still cool, but dare I say too geeky for me?

  7. nubie says:

    On perusal of the website I see there is an IR Led, I really want this, as most watch TV Remotes are useless, I need at minimum an aspect key and the number/navigate/enter keys, this is so cool.

  8. Gabriel Gray says:

    I don’t see how to make it say “Sylar” in the background.

  9. jproach says:

    nubie: if you could free up an input (maybe change the LCD to 4-bit interface?). You could add in a IR receiver.. which, with enough spare memory, would allow learning capability. Or easier, program the codes over the serial link/hardcode into firmware.

    Of course you’d have to write the firmware to handle all of this on the PIC side first.

    but seriously though, who would ever regularly use a watch as a remote.

  10. humfree says:

    >but seriously though, who would ever regularly use a watch as a remote.

    who would ever regularly use a watch as a calculator??

  11. devturkler says:

    hımm nice

  12. ragnar says:

    Hmm, for half the price I would. But I’m a tight nerd.

  13. luke says:

    price is to high, and i like my tokyo flash watches to much !

  14. Alan Parekh says:

    I wonder what the professors would have said if I had one of these during a math exam back in university?

    For small production runs the price isn’t that bad. But it does seem high when compared with anything that is produced in quantities of millions.

  15. Maj says:

    Why didn’t he just engineer a new band support?

  16. CFX-nerd says:

    Someone should try to replicate a CFX-400

  17. Bob says:

    Hey all,

    Any of these cool U-watches available for sale? Must come already assembled. I can rebuild mechanical watches, but not electronic ones. Thanks. e-mail me at

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