7 seg displays for watch

Discussion in 'General Electronics Chat' started by count_volta, Mar 9, 2010.

  1. count_volta

    Thread Starter Active Member

    Feb 4, 2009
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    Hi, I have designed a watch using 3 counter stages with D flip flops. I want to eventually build this thing in real life. My question is about 7 segment displays, or really the decoders/drivers for them.

    The decoders we use for seven seg displays cause the displays to show 0-F in hex when 0000-1111 are applied to it. Now since I am making a watch I want something a little different.

    I have 6 D flip flop outputs which represent seconds, and 6 more which represent minutes. We won't talk about hours for now, I will deal with that later.

    So the 7 seg display decoders have to take in a 6 bit binary value and show 0-60, while ignoring 61-63. Obviously you need two 7 seg displays for this, and each one must behave differently. One of them will show 0-6, and the other 0-9. So thats probably two decoders right there, one for each. The minutes portion is exactly the same.

    Now its very easy to design a decoder that does this myself, but the amount of wires and gates necessary would be crazy. My question is, are there already such decoders for 7 seg displays out there that I can buy?

    Thank you
     
    Last edited: Mar 9, 2010
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Gonna be a really large watch. To shrink it use a microcontroller.
     
  3. count_volta

    Thread Starter Active Member

    Feb 4, 2009
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    I want it to be large. ;) Well it will be the size of a radio alarm clock.

    What I'm trying to do is use only hardware. No software. I'm going old school. What I love about my design is that I understand how it works down to the cmos transistors. You can't beat that feeling. I wanna build something and be able to say, I understand how it works 150%.
     
  4. ELECTRONERD

    Senior Member

    May 26, 2009
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    That's far too easy! count_volta wants the challenge, eh? ;)

    Perhaps he can have a digital watch with the huge LED displays on the wall.

    Austin
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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  6. count_volta

    Thread Starter Active Member

    Feb 4, 2009
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    You know what I decided. I will leave it a binary watch. ;)

    Only a real EE has a binary watch on his desk. It will also help me remember my binary. I already memorized 0-15, but anything higher and I have to look it up, or convert.

    So it will display the time using LED's, and I will have little captions underneath that say minutes, seconds, hours.

    Once I'm done I will post it in the projects forum and show a little video of it. This will probably be in the summer, as I am busy with coursework right now. This is just for fun. Thanks for the help guys.

    Also, thanks Maxim's ICM7212 looks interesting and might be useful for other things I will do.

    P.S. that brings up another question, are there TTL or other chips that have 6 D flip flops? All I have is 7474, and they are dual.

    Answered my own question. The 74F174 chip.
     
    Last edited: Mar 9, 2010
  7. SgtWookie

    Expert

    Jul 17, 2007
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    I would not even put the hours, minutes and seconds caption on it.
    Any bit-twiddler (programmer/analyst) or other person familiar with digital electronics should recognize what it is within a few moments, and be able to read it, too.

    Why not design the clock so that you can switch between BCD and HEX display modes?
     
  8. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    I want to see a picture of that baby on your wrist! :)


    You will be the envy of nerds everywhere! :)
     
  9. count_volta

    Thread Starter Active Member

    Feb 4, 2009
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    You very well may. We live in the same city. :D
     
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