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Keypad to dual 7-segment display circuit

Discussion in 'General Electronics Discussion' started by RogerB, Sep 12, 2012.

  1. RogerB

    RogerB

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    Sep 12, 2012
    Hi Folks,

    I want to build an indicator panel that allows an operator to key-in a 2 digit number from a small keypad in one part of the room that then displays the numbers in another part of the room. Ideally there would also be a repeater display at the original end.

    I have only a basic electronics knowledge so any help would be appreciated please.

    Regards

    RogerB
     
  2. CocaCola

    CocaCola

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    Apr 7, 2012
    This is simple enough with a micro, but may I asked why? Wireless or wired? Without using a micro the circuit gets more complicated but it's still doable...
     
  3. RogerB

    RogerB

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    Sep 12, 2012
    Hi CocaCola,

    My room isn't too big and has other wireless things in it. When you refer to 'use a micro' are you meaning use a PIC?

    RogerB
     
  4. CocaCola

    CocaCola

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    Apr 7, 2012
    Too big for what? Wired or wireless can easily reach 100s or 1000s of feet without a problem, it just needs to be designed to do that distance...

    PIC and AVR would be the two most popular, but you could use whatever brand you want... You would just need to learn how to program and purchase the necessary stuff to get it rolling...

    Again I asked, what is the purpose? Seems like a meaningless exercise unless it's for a school project or just a proof of concept...
     
  5. RogerB

    RogerB

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    Sep 12, 2012
    [Again I asked, what is the purpose? Seems like a meaningless exercise unless it's for a school project or just a proof of concept...[/QUOTE]

    I have a railway layout that has a front and back area; it is operated by 2 people, one in each area and when one is sending a train to the other, it is necessary to know the number of the engine (I am using DCC where each engine has a unique callsign number) which is approaching your area so that you may take control if this is necessary.

    The reason I said the room isn't too big is that it probably wouldn't justify a wireless solution.

    In passing, I have to say that when I joined this forum, I didn't envisage that I would have to justify why I want to do something, rather that some kind folk would point me in the right direction.
     
  6. donkey

    donkey

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    Feb 26, 2011
    rogerb the reason for the justification was to see if it was homework or not, not a shot at your project. we totally endorse those who use us to help with homework but we really don't want to do all the work for you.

    you mention pic and you can use this if you wish but there are alternatives. but if you know about PIC then by all means use it.
    wireless communictaion is the issue I am going to talk about though. you say your room isn't that big to justify a wireless solution and it has other wireless devices. I just want to point out that a wireless solution isn't always about distance. I could hook my phone to the computer to upload songs via a chord, but I use wifi or bluetooth cos it saves my computer having more wires.

    also I just want to ask one last thing you say you send the engines from one side to the other. wouldn't both sides need to be able to send locomotive numbers? ie you are on the front and tell your friend engine 25 is heading to him, he has to clear room and sends you engine 14 but he has no keypad to tell you that.
     
  7. donkey

    donkey

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    Feb 26, 2011
    oh and I totally missed it. but WELCOME to the forums, hope you enjoy them
     
  8. CocaCola

    CocaCola

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    Apr 7, 2012
    As Donkey stated I was simply feeling out the reason for your project as it seemed more like a 'school' proof of concept exercise vs a practical application... Now that you have explained the application we can not only further assist you but we can likely offer up alternatives that you might not have thought of... If it was a school project we would have expected you to at give the main input and we would only give guidance...

    How many trains are there? I asked because it might be easier to simply have a bank of buttons and pressing a button for any particular train lights a specific number on both the displays... Doing it this way is arguably 'easier' if you do not want to get into a micro solution... Input?

    Do you have any experience with microcontrollers?
     
  9. RogerB

    RogerB

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    Sep 12, 2012
    Thank you both,

    I have about 30 engines and that number will fluctuate as the layout matures. I have no experience of microcontrollers, which is why was thinking of the wired approach. Certainly there will be a need for doing it the opposite way too, but I thought that if I could get it going one way, I could just duplicate to go the other way.

    For me to design a system to go 'duplex' would be well beyond me.

    My homework days are well behind me now, being 70 and pushing hard!
     
  10. BobK

    BobK

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    Jan 5, 2010
    I would do this with a micro on each side and serial line between them. You would build two identical boards with the micro, keypad and display.

    Since you are not experienced with micros, it might be easier to look for a development board that is already set up with a keypad and display. This would be a lot more costly, but less learning.

    Bob
     
  11. BobK

    BobK

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    Jan 5, 2010
  12. donkey

    donkey

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    Feb 26, 2011
    That board has the display with the keypad. how easy would it be to hook it up so the keypad on one shows numbers on the other and vice versa?
    the display for keypad a has to be on other side of track from description.
     
  13. BobK

    BobK

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    Jan 5, 2010
    You could do that, but I was thinking of using a serial interface between the two boards, and each display could show the number entered on both keypads on its 4 digits. You are going to need to program the PIC anyway.

    Bob
     
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