Rpi 4 and two monitors

NathTheDude · Feb 5, 2020, 2:14 PM

@sdetweil , yeah buster.

I can see temples on both screens, the image does not flow between screens. When looking at the 'Appearance Settings’, the is a tab for each HMDI with different settings but these are purely for what image is seen on the desktop. You can use the same image on both desktops however this is purely related to the desktop image or so is what I understand of it.

NathTheDude · Feb 5, 2020, 2:22 PM

@NathTheDude said in Rpi 4 and two monitors:

@sdetweil , I opened up a terminal session on each screen and both indicated the same display was being used (:0).

From the ‘Appearance Settings’ window (‘Prefences’ > ‘Apprearance Settings’, there is a ‘Taskbar’ tab and in this tab you select which hdmi output you want the taskbar to be on. You can choose both.

Sorry, with my previous comment - I meant to say you ‘CANT’ choose both (taskbar can only be on one screen/output).

sdetweil · Feb 5, 2020, 3:34 PM

@NathTheDude there is a firmware update on the pi4… execute

sudo rpi-update

NathTheDude · Feb 5, 2020, 5:53 PM

@sdetweil , so I did the firmware update and rebooted.

Slightly different now but still can not quite get this to work. When I now run a terminal on screen 1 the output of ‘echo $DISPLAY’ is ‘:0.0’ and when I run the terminal on the 2nd window the output is ‘:0’. However the same is seen when I try to either user ‘0’ or ‘0.0’ in run.sh (mm gets display on the 1st monitor.

I have again tried to use different numbers (1,2,3 and 0.1, 0.2, 0.3) but again, these are not valid entries.

sdetweil · Feb 5, 2020, 6:10 PM

@NathTheDude how about the output of xrandr -q

NathTheDude · Feb 5, 2020, 6:17 PM

@sdetweil . I get the following when trying to run different xrandr commands:

Can't open display

NathTheDude · Feb 5, 2020, 6:24 PM

@sdetweil - ahhh. I need to do this from the desktop:

pi@MagicMirrors:~ $ xrandr -q
Screen 0: minimum 320 x 200, current 2160 x 1920, maximum 7680 x 7680
HDMI-1 connected primary 1080x1920+0+0 left (normal left inverted right x axis y axis) 477mm x 268mm
   1920x1080     60.00*+  60.00    50.00    59.94  
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x720      60.00    60.00    50.00    59.94  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   720x576       50.00    50.00    50.00  
   720x480       60.00    60.00    59.94    59.94    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94    59.94  
   720x400       70.08  
HDMI-2 connected 1080x1920+1080+0 right (normal left inverted right x axis y axis) 477mm x 268mm
   1920x1080     60.00*+  60.00    50.00    59.94  
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x720      60.00    60.00    50.00    59.94  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   720x576       50.00    50.00    50.00  
   720x480       60.00    60.00    59.94    59.94    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94    59.94  
   720x400       70.08  
pi@MagicMirrors:~ $

sdetweil · Feb 5, 2020, 9:03 PM

@NathTheDude ok, I can see the same results now that I have my adapter…

may have to wait til tomorrow to work on it…

NathTheDude · Feb 5, 2020, 9:49 PM

Hey @sdetweil , no problem at all - no rush indeed. Thank you for your help thus far.

So thanks to this page I have been able to run up two chromiums, one on each page but I have started up chromium directly via terminal from the desktop. Not quite figured out how to implement this as two MM’s and if running up two at once would kill the CPU.

raspberrypi.org forum post

1st terminal session

DISPLAY=:0 /usr/bin/chromium-browser \
--noerrdialogs \
--kiosk \
--window-position=0,0 \
--start-fullscreen \
--user-data-dir=Default

2nd terminal session

DISPLAY=:0 /usr/bin/chromium-browser \
--noerrdialogs \
--kiosk \
--window-position=1920,0 \
--start-fullscreen \
--user-data-dir=‘Test2’

sdetweil · Feb 7, 2020, 3:42 PM

@NathTheDude copy one MM folder tree to MagicMirror1

then change the config on MM1 to use a different port (8081 maybe)

then start both MM in serverOnly mode (u can set that in config.js too, serverOnly: true,

then launch your two browsers, with the url pointing to separate MM’s…
–app=http://localhost:MM_port,
–app=http://localhost:MM1_port

you can edit the run-start.sh on MM1 to add the

--window-position=1920,0 \
--user-data-dir=‘Test2’

parms to the ones already provided

then change both MM configs to serverOnly: “local”,
and it will launch the chrome browser for you
(this is what we call split mode, using a separate browser)

then u can have pm2 start both of those when the system boots…
have to change the mm.sh in MM1/installers, and maybe the json file title to MagicMirror1, and point to the local mm.sh