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HDMI Signaling

Discussion in 'General Electronics Discussion' started by Macgyver, Jun 1, 2018.

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  1. Macgyver


    Jun 1, 2018
    Hello newbie here,

    I'm looking to trigger a status light to tell me when a specific HDMI signal is being physically used. My setup has a high end switcher that the customer switches on a whim to see different inputs on a monitor

    In short, when HDMI signal 1 is in use I'd like to see a green light, when not in use a red. Does anyway exist to measure the "load" that the RGB Timing circuit is under to achieve this task? This in turn would signal a low voltage circuit/relay to trigger the appropriate status light.

    Thanks for any help.
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Welcome to EP.
    You will not see a physical change (like e.g. avoltage drop) when the HDMI signal is used. Monitoring the HDMI signal and finding out which one has the active connecion´(by analyzing the handshae that's going on) may be possible but surely is way above what you want to achieve.

    It may be the easiest way to tap into the HDMI switch an dget the indication from there.
  3. Macgyver


    Jun 1, 2018

    Thank you for the reply, yea I thought about that but from time to time the switchers change. I've been trying to research how HDMI's work and to no success can't find really good info. Does any of the 19 pin info change while physically being used? Any circuits I can build? I know its DC, I know about the handshakes etc but am unaware of any active back and forth that physically says "hey wake up" I'm in use now.
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Not that I knew. Other experts may chime in?
  5. mr fixit

    mr fixit

    Jun 23, 2013
    I am not an expert, but I will chime in anyway...

    I bought an HDMI switch a while ago (ebay - VERY cheap). It has 5 inputs and one output, a remote control and it is "automatic" to boot!

    And it has lights on each input that are ON when that input is selected, whether by the remote, or the button on the device or by automatic operation.

    Not sure what drives the lights because, despite my penchant to do so, I haven't opened it up!

    The automatic function is just last in, best dressed. Ie the latest HDMI device to have a valid input is the one that is fed to the output. When that input goes back to the inactive state, the device switches back to the previous one that was active. This is really handy as you could have a TV on one input and a DVD player etc on another. While watching TV, you power up the DVD player. The switch automatically switches to the DVD player. You watch your DVD and when finished, switch it off. The switch will revert back to the TV input.

    The lights for each channel are red leds, but that could easily be fed to a circuit that shows a green led for the active channel and a red for the inactive ones.

    To switch the device between inputs manually, it has one button that cycles through each input in turn.

    Could your customer use such a device instead of the one he has?
    Harald Kapp likes this.
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