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24v Keypad - Microcontroller

Discussion in 'Microcontrollers, Programming and IoT' started by Sadlercomfort, Dec 9, 2015.

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  1. Sadlercomfort

    Sadlercomfort Ash

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    Feb 9, 2013
    Hi guys,

    Does anyone know how to interface a 24v keypad to a microcontroller.

    Usually I would use a 5v keypad and connect it directly to one of the ports with pull up resistors. However I can only find a 24v one for cheap on farnell so I have to use this.

    http://www.farnell.com/datasheets/1804053.pdf

    Is this a 24v max rating? Or do i need to use 24v?

    Thanks,
    Ash
     
  2. Minder

    Minder

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    Apr 24, 2015
    Those KB's are passive devices, just tactile switch so 5v or 24v does not really matter, they are set up with a matrix to save on I/O, see the tutor series by Nigel Goodwin Tutorial site.
    M.
     
  3. Sadlercomfort

    Sadlercomfort Ash

    424
    53
    Feb 9, 2013
    Oh okay,

    So its safe to say i can use anything from 5V to 24V.
     
  4. Minder

    Minder

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    Apr 24, 2015
    As long as you observe the 50ma rating.
    Correction, I see they have a ilumination LED they mention 5v for these?
    Separate connections.
    M.
     
    Sadlercomfort likes this.
  5. Minder

    Minder

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    Apr 24, 2015
    To follow up it appears that the keyswitches are anything up to 24vdc rated, the diode anode/cathode is 5v, I am assuming that there is internal series resistors, it does not mention the inner connections.
    M.
     
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