RPi4 can use an iPad Pro as an HDMI screen (click link below)


Scroll down - there is a follow up for video, works for ANY iPad!

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You can also use an Android device with an X Server application such as XSDL. I did this quite a bit whilst testing different screen sizes and touchscreen. It works fairly well but there is always the worry that the network will drop out so I wouldn’t want to use it for a performance unit. Handy for testing though! (I liked being able to take the display to another room to sit by the fire whilst testing bits or writing bug reports :slight_smile: .)


Hi Riban … since you have been my savior once before … I take advantage of your expertise to ask which Android SSH app do you use with the X server? I have tried Mobile SSH but it does not allow me to enable X11 Forwarding like for PUTTY.
Thanks in advance

I don’t think there is the same option on Android - or rather I haven’t thought to look for one.

I have used X Server XSDL as an X server on Android then a separate SSH session to forward to that display. When it starts up it shows a screen allowing configuration then shows the X server with instructions on how to connect. It is fairly self documenting but if you got a small get back to me.

Are we :face_with_monocle: ing him for this…?

I tried but not having the necessary skills I do a bit of “mess”. Most likely the wrong way to proceed: I open xsdl which gives me the screenshot that I am attaching. To this then remaining on the android device I have reported the command strings indicated in the attached screen but nothing happens. It is most likely a problem with ssh and x11 configurations that I am missing.

You need to ssh to your linux device, e.g. Zynthian then run the commands, e.g.

ssh root@zynthian.local
systemctl stop zynthian
export DISPLAY=
cd /zynthian/zynthian-ui

The export command sets an environmental variable called DISPLAY to the value and makes it available for subsequent commands in this ssh session. A X11 application like Zynthian will attempt to display its output on the X-server located by the DISPLAY envirnomental variable, in this case display :1 on host

Again Riban hit the mark. But I was disappointed because in any case exporting the GUI to an external mobile device zynthian no longer responds to commands and no longer plays. I tried with Pianoteq; i exported the graphical interface … but zynthian does not respond to the commands given via the external device (for example: does not change presets).
Another problem is the configuration of the graphic resolution.
I don’t know … I’m probably doing something wrong.