Trouble reading buttons on a DVD player front panel

Discussion in 'The Projects Forum' started by Casch, Aug 5, 2014.

  1. Casch

    Thread Starter New Member

    Aug 5, 2014
    I'm working on a Raspberry Pi media center project where I'm building a RPi into an old DVD player. It should be a sinch, but what I expected to be the easy part has turned out to be beyond my limited experience.

    The front panel has six buttons, an LED and an IR sensor. From appearances it's a quite simple board, with nothing but buttons, a few resistors and a couple capacitors. But the buttons are rigged together in a strange way, and the main DVD controller board has Clock, Strobe and Data pins connected to read the button states.

    Given there's no logic on the front panel, why would this be?? Can anyone make sense of the circuit illustration attached?

    I'm tempted to try soldering the existing buttons directly to a shift register and calling it good. Though I'm hoping there's a way to use the existing headers on the board.
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    It is common in appliances to have the buttons multiplexed in some weird way.

    Probably you best bet at an easy success is to use some small 5v SPST relays, one for each button. Then just connect the relay contacts in parallel with the button.

    PS. PLEASE shrink your photos first, before attaching them to the forum! That photo is 3200 pixels wide and 1.7Mb. :(

    Something around 640*480 pixels is a good forum friendly size. :)
  3. Casch

    Thread Starter New Member

    Aug 5, 2014
    Thanks for the suggestion :) I posted from my phone and couldn't be bothered to resize the pic - I figured it was within the size limit and most everyone has bandwidth to spare ;)