BCD 7 Segment up down counter with Thumbwheel switch

Discussion in 'Digital Circuit Design' started by KimChuan Tham, Jun 26, 2016.

  1. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    Im currently trying to build a circuit on BCD 7segment up down counter with thumbwheel switch and im totally clueless on what kind of components should be used and how the circuit is to be formed. Please help me
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    You can get a thumb-wheel switch with a binary-converted-decimal (BCD) output. BCD is a 4-bit representation of decimal numbers 0-9. (Google BCD for clarity).

    Then get a CD 4511 chip that accepts the BCD "data" as an input. The CD4511 will output all the signals for segments a to g for a common anode 7-segment display. The output will display the new digit as your thumbwheel sends the new BCD value to light the next digit - up or down depends on which way you turn the thumb wheel.

    Something like this where your BCD thumbwheel switch is shown with four separate (simplified) switches. Depending on your thumbwheel, you may need pull-up resistors.
     
    Last edited: Jun 26, 2016
  3. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    Do you mind helping me design the circuit out? I really have 0 knowledge on how its gonna be
     
  4. MaxHeadRoom

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    Jul 18, 2013
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    Is the T.W. switch BCD output?
    Max.
     
  5. GopherT

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    Something like this. You'll need to read the datasheet for the thumbwheel switch that you have to get the right pins to the right place (and google cd4511 to get the right pin assignments for the cd4511 and so on. Datasheets are your friend.

    image.jpg
     
  6. JohnInTX

    Moderator

    Jun 26, 2012
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    @KimChuan Tham
    Please do not open more than one thread for a question. I have combined your threads here.
    Welcome to AAC!
     
  7. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    so as for up down counter i just have to do 2 of that?
     
  8. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    yes
     
  9. KimChuan Tham

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    Jun 26, 2016
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    Anyway, things like 555-timer isnt required?
     
  10. crutschow

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    Mar 14, 2008
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    If you want the thumb-wheel switch to input the count value to an up/down counter then you would also need a BCD counter, such as the CD4510, to go in front of the CD4511, which is just a BCD to 7-segment decoder.
    Or is all you want just to read out the thumb-wheel BCD value?
     
  11. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    what i need to do actually is something like a stop watch and an alarm. i need it to count downward and also count upward. what my teacher require me to do is to use 7 segment and thumbwheel switch. the rest is for me to find out. thats why im seeking help if someone knows how the circuit is suppose to be like
     
  12. GopherT

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    What is the thumbwheel supposed to do? Set the start time of a countdown timer?
     
  13. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    yeap it is to set the time
     
  14. GopherT

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    Then this can be done with:

    - 555 timer pulsing away (or CD4060 if you want higher accuracy) sending signal out to...
    - CD4510 to convert those pulses to a binary value and send that binary value out to...
    - CD4511 which translates the binary value to drive the segments of a...
    - 7-segment display

    You will need switches to
    - "latch" the value of the thumbwheel (when needed)
    - tell the 4510 chip to count up or down
    - clear/reset the 4510 chip to restart (could be the same as the latching switch)

    Start with the Datasheets and there are plenty of circuits online that you can search to get you started.

    If you are so lost that this does not help you, go talk to your professor - he needs to know that either:
    - his lectures are not working
    - you do not have the background to be in this class
     
  15. KimChuan Tham

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    Jun 26, 2016
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    will it be easier if i use a microcontroller?
     
  16. MaxHeadRoom

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    Probably yes, but you would have to adopt some programming skills.
    Max.
     
  17. KimChuan Tham

    Thread Starter New Member

    Jun 26, 2016
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    Just to clarify, what if i dont want any programming to be included in my project. And only 7segment, thumbwheel switch(to set the numbers), and ics to be on my breadboard, what ics do i need to use and is there anything im missing out like a counter or something
     
  18. MaxHeadRoom

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    Jul 18, 2013
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    Then a micro is out then!.
    Max.
     
  19. shteii01

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    Feb 19, 2010
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    Do a block diagram, label the blocks according to the function you want them to perform.
     
  20. crutschow

    Expert

    Mar 14, 2008
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    You don't seem to be tracking the posts. :rolleyes:
    It has already been established that you need a counter and a part number has been given for that.
     
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