BeagleBone local setup - Black screen with cursor after graphical login

[Pierre Ingels]

Hello all,

I am attempting to set up a controller for my CNC lathe using the BeagleBone Black and Machinekit. I have set it up pretty well using remote terminal and I am now completing the system with a touchscreen (an Elecrow RR101 10.1 Inch 1280x800).

It seems to work just fine and displaying the login graphical interface at 1280x800, but as soon as I login the mouse cursor remains but the screen is all dark. I have poked around with Xrandr thinking that it is the resolution but I get this message:

xrandr: Failed to get size of gamma for output default

Screen 0: minimum 1280 x 800, current 1280 x 800, maximum 1280 x 800

default connected 1280x800+0+0 0mm x 0mm

   1280x800       0.00*

I assume that I have to define the screen - any pointers how to do this and find the relevant parameters? Or obviously if I need to look in a very different direction :)

Thank you!

Pierre

[Jeff Pollard]

Hi,

  Some versions of MachineKit do not come with the desktop environment installed.  I'm not sure if that is the problem you are encountering, but I had a similar problem before.  I installed lxde as a desktop (remotely) then rebooted, and I got a desktop display after logging in. 

Jeff

[Pierre Ingels]

Thanks Jeff for the tip! I just installed lxde and ensured that it is enabled but am getting the same black screen with cursor visible. 

I'll have to look probably more in the configs as there seems to be something inhibiting the drawing of the interface.

Pierre

[Pierre Ingels]

Making progress - although in a curve :)

To try and problemsolve I connected a Raspberry Pi to the problematic monitor - intiially it had the same issue (black screen after boot) and here I managed to solve it by forcing hdmi_group=2 and hdmi_mode=27 in config.txt... (https://www.raspberrypi.org/documentation/configuration/config-txt/video.md)

So it clearly seems to be that the monitor demands a non-standard resolution (1280x800 @60Hz) and the system does not seem to jump to it automatically.

Back to the BeageBone though, I feel a bit lost: the file structure is different and there doesn't seem to be a config.txt that forces common environment variables?

Is there any equivalent, or a way to force the resolution on HDMI to be 1280x800?

Thanks!

Pierre

[Jason Kridner]

yes, the video argument in /boot/uEnv.txt

https://elinux.org/Beagleboard:BeagleBoneBlack_HDMI

On Jun 1, 2020, at 5:41 AM, Pierre Ingels <pie...@ingels.eu> wrote:



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[shahim vedaei]

Hi,

Any success regarding your issue? What was the cause of that no desktop.