Getting picture when 2 screens are connected. 7" screen and 27"monitor

[Soxbrother]

I have made a Raspberry pi4b powered handheld.

I have 2 screens,
a 7" raspberry pi screen and a 27" Samsung monitor.

Hdmi0 is the 7' screen

Hdmi1 is the Samsung 27" monitor
(Connected with micro hdmi extension cable)

All I want to be able to do is :

• Get picture on hdmi0 when the monitor isn't connected to the extension cable.

• Get picture on hdmi1, when the monitor is connected to the extension cable

So I'm not looking for screen mirroring, but just be able to get picture on the monitor while it's connected.

As it is now, Hdmi0 displays Retropie flawlessly, but I can't get picture on the monitor, probably because the hdmi0 is connected to the 7" screen.

Hdmi0 is in fact the primary connection.

So hopefully a solution would be to simply swap the 2 cables.
Making it so that hdm0 is the Samsung monitor and hdmi1 is the 7" screen.

So that when the monitor is disconnected (extension cable stays connected),
the Raspberry Pi allows giving picture to hdmi1.
(Which would then be the 7" screen)

I hope this all makes sence to you Raspberry Pi experts out there.

Thanks for any help in advance.

Greetings,
Soxbrother

The reasons I want to have picture on the monitor are :

because editing things would be a lot easier, than on a smaller screen.
I guess gaming on a bigger screen, also is a good option.

[mitu]

@soxbrother said in How to get picture on both screens at the same time ? Pi4 handheld and monitor:

How can I mirror the output from the primary hdmi to the secondary screen ?

That works only if you're using the desktop/X.org, using arandr/xrandr or the screen configuration utility shipped with the Raspberry Pi OS. RetroPie doesn't use the desktop environmant though, so it's not installed by default - see https://retropie.org.uk/docs/FAQ/#where-did-the-desktop-go.

disabeling the primary hdmi port, till you enable it again

I think vcgencmd display_power can disable disable/enable a HDMI port with

vcgencmd display_power <state> <display_number>

where <display_number> is one of 2 or 7, see https://www.raspberrypi.com/documentation/computers/os.html#display_power-0-1-1-display.

[Soxbrother]

@mitu Thanks for the reply.
I have edited the opening text of the the topic,
so everyone can better understand,
what it is I want to achieve.

I think I'm going to try to swapping the cables first.

In this new scenario there will be nothing attached to the hdmi0 port,
(apart from the extension cable)
so that should hopefully give me picture on the hdmi1 port.

And when the hdmi0 port is connected to the monitor, the hdmi1 port would display nothing, only the boottext.

Before when both 7" screen (port 1) and monitor (port 2) where connected, I tried the option framebuffer_priority= 7, which I had found, but it didn't do anything, probably because the hdmi0 port was connected to something.

[Soxbrother]

@mitu said in Getting picture when 2 screens are connected. 7" screen and 27"monitor:

I've tried swapping the cables, and it worked from the first try.

I now have picture on the 7" screen, which is now connected to hdmi1 and when I connect the 27" monitor to hdmi0, I get picture on the monitor. The 7" screen then displays a rainbow color screen and then goes blank.

The 7" screen only displays the launching screen, when I play a game.

I immediately tried an arcade game, the launching screen displayed, but then went back to the main menu.
I've tried other consoles, they all seem to work.

I've tried 2 other arcade games, which seems to work.

Coincidence or not, the game I tried first has a bezel overlay.
Maybe the monitor can't handle that for some reason ?

I will disable the bezel and see if it runs then.