Rpi 4 and two monitors

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

sdetweil

well, I finally got it to work , note I have two displays that support 4k, 3840x2160, so my screen pos is double yours

in /boot/config.txt

[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
dtoverlay=vc4-fkms-v3d
max_framebuffers=4

and in /boot/cmdline.txt
add cma=384M to the end of the line, like this…

plymouth.ignore-serial-consoles cma=384M

then you must power down and back up for these changes to be applied

found here
https://retropie.org.uk/forum/topic/24436/drm_ioctl_mode_create_dumb-failed-cannot-allocate-memory/9

I was getting the DRM cannot allocate memory error

MagicMirror/run-start.sh line for chromium

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

MagicMirror2/run-start.sh line for chromium

chromium-browser --disable-bundled-ppapi-flash -noerrdialogs -kiosk -start_maximized  --window-position="3840,0" --disable-infobars --app=http://localhost:$port  --ignore-certificate-errors-spki-list --ignore-ssl-errors --ignore-certificate-errors  --user-data-dir='Test2'  # 2>/dev/null

this boots up and both MM start via pm2 and display on separate screens, with different content (modules in different positions)

here is a screenshot of my dev system connected to both MM servers at the same time
(the displays are two hdmi ports on the same TV, so I can’t show them physically at the same time)
alt text

NathTheDude

@sdetweil - nice 2 x 4k’s.

So, I did what you mentioned in your last post but unfortunetly I am in the same issue. I wonder if your problem was more to do with 2 x 4k’s which is perhaps different to mine? I am not sure.

NathTheDude

@sdetweil - if you comment out the chromium line in the run-start.sh does this cause you any issues/errors?

sdetweil

@NathTheDude no… you could just change config.js to serverOnly:true, then it won’t try to start chrome

sdetweil

@NathTheDude I started by doing

cd MagicMirror
node serveronly

note no npm start needed, will run til you ctrl-break out

then tried multiple tries to get chrome on the second display…
(it works manually if the position is mispelled!)

then once it worked reliably,
i killed the server instance
then I used pm2 to stop/start that instance til I got that to work.

note that I had to use
–disable-bundled-ppapi-flash
on the second instance as it collided with the 1st…

krocaq

@sdetweil

@saljoke
Hi. Thats right. i only use 1 Pi4 to serve both displays via 2 MM instances. first the originally MagicMirror directory and the second in a MagicMirror2 directory. Both powered up via PM2 and turned off and on via PIR sensor.

The config looks like this:

language: “de”,
logLevel: [“INFO”, “LOG”, “WARN”, “ERROR”],
timeFormat: 24,
units: “metric”,
electronOptions: {fullscreen:true, x:1920},

1920 is the resolution witdh of the main display.

Very easy to handle and good for the electrical consumption

sdetweil

@krocaq see my comment here , you can do it with ONE directory
https://forum.magicmirror.builders/topic/17239/two-display/2?_=1663555322286