I have a Samsung Galaxy A9 which I'm trying to connect to an external HDMI display by the means of a commonly-found USB-C to HDMI adapter like this one. Connecting the USB-C input "lights up" the adapter, and Android shows the adapter as charging, but it does not work with multiple HDMI cables and monitors.

After searching everywhere with no avail, I noticed that the notification area shows that adapter - briefly - connects and disconnects multiple times before it disconnects permanently (while still showing that the adapter is being charged).

Some screenshots:

Here the USB connector is shown connected (it disconnects soon afterwards, but I couldn't get a good shot of it) and charging.

Now the device has "disconnected" (I presume?) yet still charging.

I also tried forcing the phone to act as a host of the connection in the settings, but that also fails.

How can I enable USB OTG in my device (if it's not already enabled)? I take that the device should be able to do this screen sharing since it was produced in 2018, and I've seen older devices in videos performing it just as well. What can I do to fix this USB error and enable other things (such as a USB hub or a keyboard) to be used together with the phone?

Similar questions to this one are very old and not quite close, so that's why I'm asking again.

Many thanks, feedback is appreciated.

  • 2
    Common USB-C to HDMI/DisplayPort adapters require that the USB-C source port contains a DisplayPort signal on the USB-C alternate mode connector pins. Currently the list of smartphones that support a DisplayPort signal via alternate alternate mode is not very long. I found this list: en.everybodywiki.com/…
    – Robert
    Aug 20, 2020 at 17:20
  • Thanks, Robert, this helps. I already see my phone isn't on the list (my mistake, perhaps), but that doesn't explain the other side of the question about the USB interface itself. Perhaps I should "activate it" somehow? Or is there a similar list for USB OTG support?
    – palimaar
    Aug 21, 2020 at 1:11

1 Answer 1


It turns out that my device is not HDMI-compatible and will not transmit over that adapter (or any other, apparently).

Props to Robert for finding a (generic?) listing over here:


(In case anybody else is googling this and can't find a solution, I highly recommend checking your device against the list above.)

Whereas at first I was a little skeptic of this insight, buying a USB-C to USB-A adapter and testing out with other devices like a USB mouse or keyboard confirmed that the port itself has no issue - it's the HDMI output that has a problem.

I'll look into alternatives on how to cast my screen in another way.

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