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wiring LCD to display content, triggered by pressure sensor

Discussion in 'Sensors and Actuators' started by Fraseraa, Jul 2, 2014.

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  1. Fraseraa

    Fraseraa

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    Jul 2, 2014
    Hey Guys,
    I am working on a board game project, and want to wire an LCD screen into the centre of the game, and have pressure sensors at each level in the board game, so that when the person playing the game moves the token (figure) to a new position the pressure sensor triggers the LCD to display a message and/or picture. The effect I am trying to get is similar to the green display screen in Jumanji. If anyone has any knowledge on how I can possibly accomplish this, I would greatly appreciate it. You can post on here of email me directly: [email address removed by moderator (Harald)]

    Best Regards
    Fraser
     
    Last edited by a moderator: Jul 2, 2014
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    How much experience do you have with Electronics and Programming?
    Also, how many levels do you plan to monitor with pressure sensors?

    Take a look at some of these:
    http://en.wikipedia.org/wiki/List_of_single-board_computers
    (I own a couple Raspberry Pi boards, so these things would be my go-to)
    They are small single board computers that have general purpose inputs and outputs that you can use to monitor your sensors. They have a decent amount of processing power, so they could give you a really nice visual on a small LCD that you want to use.

    If all your after is simple text, you can look at simple MicroControllers instead, but they may be harder to work with.
     
  3. Fraseraa

    Fraseraa

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    Jul 2, 2014
    Thank you for your reply,
    To be honest I have no experience with Electronics and Programming . However I am a fast learner and willing to do what ever it takes. I have 2 weeks to complete this project, do you think it is possible to do in this time? If your up for it, I would be keen to meet up with you and work on it together, and in return I can help you with something you need a hand with. The raspberry Pi boards sound good.

    I really appreciate you response.

    Cheers
     
  4. Fraseraa

    Fraseraa

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    Jul 2, 2014
    The levels would be 20+
     
  5. Gryd3

    Gryd3

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    Jun 25, 2014
    Well. Couple things.
    I've got a full time job and a 1yr old that I use as an excuse for procrastinating.
    I live in the Fraser Valley (Southern BC, Canada)

    I am not your best bet at getting your project done in 2-weeks unfortunately.
    I do have a couple of suggestions for your build though.
    *perhaps others on the site will point out other alternatives.

    Pressure sensors may be difficult to use depending on which one you want... (I can think of two types at the moment... variable resistance 'force sensors' and the flat plastic pad type of momentary button that I have seen used in keyboards)
    The analogue values returned by the 'force' pressure sensors would require a bit more support circuitry to be able to read all 20+ of them. The digital type (on/off only) pressure sensors may be difficult to use if the game pieces are too light to trigger the sensor.

    Might I suggest a reed switch? (given that the levels are far enough apart)
    They can be incredibly small, which can help you conceal them, and all that is required is a small magnet in the bottom of the pawn or game piece.
    Your circuit would include all of your levels sensors (preferable Normally Open switch or button) connected in rows, or multiplexed together so that your RaspberryPi or other 'brain' can poll the switches once in a while to see if any game pieces have moved and determine which level has most recently been pushed or landed on. You do not need an instantaneous response, so a separate input for each button is not needed and is wasteful.
    Once the hardware is complete, you will need to program your 'brain' to record the current state of each button (if you have multiple players) each time it polls the board, and if a new button is pressed do an action.(make sure it stays pressed... as I personally jump my pawn onto each square as I proceed... you would hate to trigger each level when doing so)
    Your action can be simple text on an LCD character display, or a video clip played on a small LCD/LED screen.

    Reed Switch:
    http://www.digikey.ca/product-detail/en/CT10-1540-G1/306-1124-2-ND/388961
    Small Push Button:
    http://www.digikey.ca/product-detail/en/KS-04Q-03/EG4799-ND/2116278
    If someone can source a small film momentary push button pad... (I dont know the technical term for it)
     
  6. Fraseraa

    Fraseraa

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    Jul 2, 2014
    Well that would be difficult to build it together, considering i am in Australia.

    Your idea is excellent, Reed switch seems like the way to go, and putting magnets in the pawn pieces is easy enough. Do you think it is possible to find any video's on how to wire up the hardware?
     
  7. Gryd3

    Gryd3

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    Jun 25, 2014
    Video.. possibly..
    You'll find plenty of write-ups, and many people on here can easily help with the layout.
    I don't have anything drawn at the moment, but when I'm up again tomorrow, I'll find something useful for you.
     
  8. davenn

    davenn Moderator

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    Sep 5, 2009

    considering your lack of experience. I doubt that 2 months would be enough time
    You expect to learn in 2 weeks what it has taken most of us many, many years to learn ? ;)

    you really should have been asking for help for this project at least several months ago

    sorry to sound a bit harsh, but you need a dose of reality :)

    cheers
    Dave
     
  9. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    I have done a little more thinking on it... and due to the lack of experience, let's chop out the multiplexing of the buttons/sensors.
    Here is a part below that can read 8 buttons at a time, and then send the data over a serial connection. The best part... they can be daisy chained together! so if you need 80 inputs... grab 10 of em.
    http://www.digikey.ca/product-detail/en/SN74HC165N/296-8251-5-ND/376966

    Your circuit would grab the state of all of the buttons at once, then shift the result to the micro controller in a serial format which would be easier to program and troubleshoot.
     
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