CEC adapter not initializing correctly

1st Official Post

    Hi Folks,

    I’ve been thinking of upgrading from a raspberry running XBMC to an Intel NUC running libreElec. Since the NUC does not support CEC on the HDMI port natively like the raspberry does, i also got a pulse-eight CEC adapter. I am using a projector (EPSON TW-5910) as the screen. CEC on the raspberry has been working for years, so i am confident that this is not a hardware or cable issue (which usually is the first answer anyone gets when asking about CEC anywhere)

    So, here is my problem:
    When i boot the NUC, with a turned on projector, i do not get a screen at all. There is simply no output signal to the projector. If i reboot via pressing the power button (short), waiting until the NUC shuts down, and then turn it back on, the same persists - i can't even see the BIOS on either boot attempt. The only thing that happens on the Projector is that it switches to HDMI-1, while the NUC is attached to HDMI-2. Switching back and forth between the HDMI ports does not yield any result - it stays the same, no output, no screen.

    However, if i hard shutdown the NUC after booting with a blank screen (holding power for 5 seconds) and then turn it back on without turning the projector off, i get video output. I see the BIOS, i see Kodi and everything works normally. Until i turn off the projector, then i have to hard reset again.

    I don't know if it has anything to do with the HDMI port confusion, but i cannot find any option to choose the HDMI port on the projector. I've seen screenshots where the HDMI channel could be set, but both, the stable (7.0.1) and the dev version (7.95.3) do not show this option to me. A screenshot is attached for the 7.0.3 version. The option to choose the HDMI channel should be right above the Physical address, at least from what i saw on screenshots.

    I'm not afraid to SSH into the box and work with the configuration/logging directly if necessary.
    I would be really happy if anyone could point me into the direction of fixing or debugging this.

    Thanks in advance

    • Official Post

    PS: if you want proper screenshots, attach a keyboard and press PrtScr. You'll find the result in the Screenshots folder. :)

    Ok, so ran a few more tests this Weekend. Turns out that the problem is not the CEC adapter (at least not alone), but a combination of the Intel NUC being silly, the Boot sequence and the init sequence of the devices.

    But, from the start.

    First, i installed LibreElec 8.0.0 (as suggest in the linked thread above) and notices that this was the first version where the Network does not kill the CEC adapter when it configures. Nice, but not the Problem at hand.

    So, on to the Screen Problem. When i plug the CEC adapter between the NUC and the Projector, and turn them on, the NUC does not initialize the HDMI port. removing the cable, plugin it back, even removing the CEC Adapter and plugin the Projector in directly does not solve the Problem. xrandr always shows the HDMI1 is inactive. No matter what is plugged in, no matter how often the NUC is rebooted. The HDMI port simply stays off a won't turn on. At least not with any command i could find.

    However, when booting the NUC once with an active HDMI connection, and then plug in the Projector afterwards, everything works. I can even remove it and replug it. The HDMI port detects the changes and configures automatically. But this only works as long as the BIOS does not get in the way of trying to be clever. So, in the end, the only work around i found was the following:

    Never shut down the NUC. Only let it go to standby. Plus, never use the Power Button on the NUC. Let the Projector turn the NUC on and off. Given these restrictions, everything works. Although, i would like to let the NUC hibernate (it uses less power that way) - but that brings the BIOS and the problems back.

    As a side note - even with the newest BIOS from Jan '17, the HDMI problem on the NUC persists.

    If anyone knows how to force xrandr to completely reinitialize the HDMI ports so the Projector can be detected after the NUC has initialized the CEC adapater, i would really appreciate it.

    Thanks