MaintenanceManWill
Posts: 7
Joined: Wed Nov 18, 2020 10:04 am

Offical Touchscreen + HDMI Mirror Display

Mon May 17, 2021 7:04 am

Hi,

I am using the official 7'' touchscreen as a VNC viewer to a HMI. I want to also mirror what is displayed on the 7"' touchscreen to a HDMI monitor but struggling to do so. At the moment when I boot the pi with the HDMI screen connected, all I get is the rainbow screen and nothing else.

Can anyone please point me in the right direction.

Many Thanks

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 11269
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: Offical Touchscreen + HDMI Mirror Display

Mon May 17, 2021 1:29 pm

What version of Pi?

Using the DRM/KMS driver vc4-fkms-v3d (default on Pi4) you get the two displays as DRM connectors, and you can tell X to mirror the desktop to the two connectors.
When running with the legacy framebuffer drivers you get two independent framebuffers (/dev/fb0 and /dev/fb1), and there isn't a simple way to clone between the two. (You may need to add "max_framebuffers=2" to /boot/config.txt to get both FBs initialised).
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

MaintenanceManWill
Posts: 7
Joined: Wed Nov 18, 2020 10:04 am

Re: Offical Touchscreen + HDMI Mirror Display

Mon May 17, 2021 8:52 pm

Hi

Sorry I forgot to mention but I am currently using Pi 3B+

MaintenanceManWill
Posts: 7
Joined: Wed Nov 18, 2020 10:04 am

Re: Offical Touchscreen + HDMI Mirror Display

Thu May 20, 2021 10:16 am

Is it possible to use this DRM/KMS driver vc4-fkms-v3d on a Pi 3, if so how do I go about installing it?

Thanks

aBUGSworstnightmare
Posts: 2953
Joined: Tue Jun 30, 2015 1:35 pm

Re: Offical Touchscreen + HDMI Mirror Display

Thu May 20, 2021 11:06 am

MaintenanceManWill wrote:
Thu May 20, 2021 10:16 am
Is it possible to use this DRM/KMS driver vc4-fkms-v3d on a Pi 3, if so how do I go about installing it?

Thanks
Change your config.txt to

Code: Select all

#dtoverlay=vc4-fkms-v3d
dtoverlay=vc4-kms-v3d
This will disable the firmware KMS driver (FKMS) and enable full KMS.
You also need to add the overlays for the touch (needed under KMS, not required under FKMS) and should be aware that there might be some issues with the 7in under KMS still.

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 11269
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: Offical Touchscreen + HDMI Mirror Display

Thu May 20, 2021 12:54 pm

aBUGSworstnightmare wrote:
Thu May 20, 2021 11:06 am
MaintenanceManWill wrote:
Thu May 20, 2021 10:16 am
Is it possible to use this DRM/KMS driver vc4-fkms-v3d on a Pi 3, if so how do I go about installing it?

Thanks
Change your config.txt to

Code: Select all

#dtoverlay=vc4-fkms-v3d
dtoverlay=vc4-kms-v3d
This will disable the firmware KMS driver (FKMS) and enable full KMS.
You also need to add the overlays for the touch (needed under KMS, not required under FKMS) and should be aware that there might be some issues with the 7in under KMS still.
NOT THE QUESTION ASKED.

For Pi3, add "dtoverlay=vc4-fkms-v3d" to one of the [all] sections of config.txt to load FKMS. You probably want to add "max_framebuffers=2" as well.
Reboot and X should see the two displays. The touchscreen driver should be automatically loaded when using FKMS (or legacy).
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

aBUGSworstnightmare
Posts: 2953
Joined: Tue Jun 30, 2015 1:35 pm

Re: Offical Touchscreen + HDMI Mirror Display

Thu May 20, 2021 3:25 pm

6by9 wrote:
Thu May 20, 2021 12:54 pm
aBUGSworstnightmare wrote:
Thu May 20, 2021 11:06 am
MaintenanceManWill wrote:
Thu May 20, 2021 10:16 am
Is it possible to use this DRM/KMS driver vc4-fkms-v3d on a Pi 3, if so how do I go about installing it?

Thanks
Change your config.txt to

Code: Select all

#dtoverlay=vc4-fkms-v3d
dtoverlay=vc4-kms-v3d
This will disable the firmware KMS driver (FKMS) and enable full KMS.
You also need to add the overlays for the touch (needed under KMS, not required under FKMS) and should be aware that there might be some issues with the 7in under KMS still.
NOT THE QUESTION ASKED.

For Pi3, add "dtoverlay=vc4-fkms-v3d" to one of the [all] sections of config.txt to load FKMS. You probably want to add "max_framebuffers=2" as well.
Reboot and X should see the two displays. The touchscreen driver should be automatically loaded when using FKMS (or legacy).
sorry, misread the question! What 6by9 pointed out works flawlessly!

MaintenanceManWill
Posts: 7
Joined: Wed Nov 18, 2020 10:04 am

Re: Offical Touchscreen + HDMI Mirror Display

Mon May 24, 2021 5:13 am

Awesome, thanks for the help.

The above information got it working. The right hand part of the screen is missing on the hdmi screen, its not the TV settings. Is it possible to adjust the resolution for the hdmi output?

If so, how do i go about this?

Many thanks again! =)

aBUGSworstnightmare
Posts: 2953
Joined: Tue Jun 30, 2015 1:35 pm

Re: Offical Touchscreen + HDMI Mirror Display

Mon May 24, 2021 5:17 am

https://www.raspberrypi.org/documentati ... -config.md

You can also adjust the resolution from the screen configuration utility. Click on the HDMI screen, select 800x480 (or the closest one) from the menu and apply the settings.
You may have to move one display, so make sure they are aligned on top of each other after you've changed the settings.

MaintenanceManWill
Posts: 7
Joined: Wed Nov 18, 2020 10:04 am

Re: Offical Touchscreen + HDMI Mirror Display

Mon May 24, 2021 7:19 am

Thanks ever so much for the help. It's looking awesome.

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