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Display message no signal after switch off hdmi

  • Hey guys,

    i installed the magicmirror on a raspi pi3. The system works really good. I try to optimize the energy consumption with a PIR.

    When i switch off the hmdi port with the following code, my display show the message “no signal” and the backlight is on too.

    tvservice -o

    I try to find a solution and play with DPMS functions, for example:

    export DISPLAY=:0 && xset dpms force off

    In this case, the message for “not signal” is not shown (good!), but the backlight is still active -.-

    I saw in this forum a lot of people do exact the same with her PIR and its working fine. I dont know what i can do to solve the issue.

    I hope you can help me with any idea 🙂

    Thanks a lot

    PS: My hardware: Display , Display Controller

  • Moderator

    Try searching the forum for libcc to put your screen into standby instead of disabling output of your hdmi port

  • I try to search somethink over libcc, but i cannot find somethink about that in the forum or google

    For set standby mode of display i found only dpms functions

  • Project Sponsor Module Developer

    @Pakmann I think that was a typo. @yawns was likely referring to LibCEC. I had the same problem as you with my screen displaying “No Signal” when the HDMI connection is put to sleep from the Pi. Using LibCEC enables you to put the display into standby and power it on.

    I currently do this using a cron job to turn the screen off and on at certain times of day, but if you wanted to get your hands dirty, it’s possible to hook up a motion sensor , and modify the MMM-PIRSensor module to execute LibCEC commands to instead of issuing the tvservice commands.

  • Moderator

    I’m sorry guys. Of course I was referring to libcec.

  • @j.e.f.f i installed libcec and scan my environment. My display could not find after scanning CEC adapter. I check the menu options and could not find any options for hmdi cec too -.-

    A crosscheck with my normal TV was okay. here i can find the tv device after scanning cec components and i can switch on/off the device with cec commands.

    Maybe someone have an other idea? Maybe i need an other display controller ?

  • Project Sponsor Module Developer

    @Pakmann Looks like your display doesn’t support CEC protocol. How old is it? CEC is relatively new – TVs built in the last 10 years or so should support CEC protocol. If it’s older than that, you might be out of luck.

  • I offered the Hardware 4 weeks ago. I think too, that cec is Not supported on the lcd Controller Board.
    I think i will solve my Problem wird a relais between controller board and Display. I can control the power supply for the display with the relais over pi. Not pretty, but it should works simple

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