Rpi 4 and two monitors

sdetweil

@NathTheDude if they are two independent desktops, then you should have a menu on the second desktop, just like the first…

also, you can move the mouse to the second desktop and do ctrl-alt-t to open a terminal there

I have an micro hdmi adapter coming later today so I can put up a second physical display on my pi4…

NathTheDude

@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.

sdetweil

@NathTheDude so, it looks like one big desktop…

u should be using Buster OS, right? so you can see the temples across the big image, some on the right display, some on the left…

NOT the same on both?

NathTheDude

@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

@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

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

sudo rpi-update

NathTheDude

@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

@NathTheDude how about the output of xrandr -q

NathTheDude

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

Can't open display

NathTheDude

@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

@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

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

@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

NathTheDude

Hey @sdetweil , thanks for the info on this - I am grateful.

I think I am nearly there but just missing a bit or two.

I copied the ‘MagicMirror’ to ‘MagicMirror2’ folder, updated the config.js, run-start.sh and the pm2_MagicMirror.json files.

When I reboot I now get MM and MM2 load up but both on the same screen.

I have messed around with the chromium line from the ‘run-start.sh’ and I don’t think it is actually be used in this case, I even commented the line out and this did not prevent me from running ‘npm start’ and MM2 still loaded albeit on top of the first MM.

Any ideas on where it is getting it’s info on how to start up chromium?

Thanks

Nathan

sdetweil

@NathTheDude sorry. I left out the pm2 steps

From mm2 folder do

pm2 start installers/pm2???.json
pm2 save

Where the json file is the one u modified.

It should start the second mirror app.

The only difference is that window-positio info. And on reboot

pm2 status should show both.

Can u show the two chromium browser lines?

I will attempt to recreate here

NathTheDude

Hey @sdetweil , after looking at how the current MM is setup with pm2 (pm2 show MagicMirror) this had the ‘mm.sh’ as the target.

Within the MM2 folder I ran: ‘pm2 start ./installers/mm.sh --name MagicMirror2’ which started the MM2 but on the first screen. Then used pm2 save.

I just setup pm2 with the .json file instead of the mm.sh file and the results seem to be the same from what i can see with it getting displayed on the first screen.

Within the start-run.sh, I can comment out the chromium line and and it will not break anything which makes me think this line is not being referenced.

MM line:

chromium-browser --noerrdialogs --kiosk --user-data-dir='Default' --window-position=0,0 --disable-infobars --app=http://localhost:$port  --ignore-certificate-errors-spki-list --ignore-ssl-errors --ignore-certificate-errors 2>/dev/null

MM2 line:

chromium-browser --noerrdialogs --kiosk  --disable-infobars --app=http://localhost:8082 --ignore-certificate-errors-spki-list --ignore-ssl-errors --ignore-certificate-errors --window-postion=1920,0 --user-data-dir='Test2' 2>/dev/null

sdetweil

@NathTheDude if u start the json file, pm2 reads the info, gives u a nice name etc.

pm2 delete 0 or 1
pm2 save

Then pm2 start the json file.
And pm2 save
To save for reboot

sdetweil

@NathTheDude

I was able to recreate the problem, and good news its just a typo

--window-postion=1920,0

should be

--window-position=1920,0

missing i in position

NathTheDude

@sdetweil

Thank you for this although it is still producing 2 x MM’s on the first screen (MM and MM2), not sure what could be wrong. If you have it working it obviously must me something I have done wrong…hmmmmm.

I will review all the files and let you know if I find anything.

NathTheDude

@sdetweil . I know it is a bit extreme but thought I would just start again and burn another image to the SD card. I am in the same position though

burnt image to sd card, booted rpi and did an update, enabled SSH and VNC
installed MM with your automation script
copied the ‘MagicMirror’ Folder to ‘MagicMirror2’, in the new folder I updated:
– config.js - just updated port to 8082
– run-start.sh - updated with window position and profile
– mm.sh - new location
– pm2_MagicMirror.json - updated with new locations
within the MagicMirror2 folder,
– pm2 start ./installers/pm2_MagicMirror.json
– pm2 save
This then started another MM from the MM2 folder on to screen 1
htop confirms that processes are running from both MagicMirror and MagicMirror2
pm2 status confirms that both are up

In your setup, if you update the chromium line within run-start.sh with bad entries does that break your setup. Does not seem to be running this command from what I can see in my setup