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I just got official raspberry pi lcd screen and it work perfectly. However, once the screen connected I cannot run the HDMI screen. I was looking at framebuffer and I thought there will be something like fb0 and fb1 so I will run the X server on each one but I only can see fb0.

What can I do to run both screens at the same time?

Mero
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  • Do you mean two identical screens ? – dhruvvyas90 Oct 09 '15 at 15:36
  • No. One 19inch screen connected by hdmi and the other is raspberry pi touch screen – Mero Oct 09 '15 at 15:38
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    Ahh.. this is very interesting question.. I wonder if its supported by the driver. I am sure the hardware can support it... but I may be wrong. It may be possible that is you use the CSI port the HDMI may be disabled.. – Piotr Kula Oct 09 '15 at 16:24
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    It's certainly possible with some touchscreens...I remembered that from here, which is a similar but not identical question. You should make it explicit in the question that this is the Pi Foundation's official screen, since that is relatively new vs. the more common Adafruit (and other similar) small TFTs. – goldilocks Oct 09 '15 at 18:00
  • I remember there was a somewhat related question: http://raspberrypi.stackexchange.com/questions/47202/dual-touch-screens-one-for-input-and-a-second-for-output – Dmitry Grigoryev Mar 01 '17 at 11:28

2 Answers2

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I was struggling with this as well since the 7" screen is a bit too small for my old eyes to do actual development.

The solution is to add a line to /boot/config.txt as described in https://www.raspberrypi.org/blog/the-eagerly-awaited-raspberry-pi-display/ :

"The Raspberry Pi will now automatically detect the display and use it as the default display (rather than HDMI), although HDMI will still be initialised. If you’d prefer for the HDMI display to stay as default then add:

display_default_lcd=0

to the config.txt file."

Cheers,

David

David Prutchi
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We cannot run two separate X because we simply don't have second frame buffer and need some development to get another frame buffer working. However, we are still capable to run both the touch and HDMI screen if the application is modified to do so. OMX player as example.

omxplayer --display 5 xxx.avi this will play the video on the HDMI screen while the X is running on the touch screen.

Mero
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  • More precisely, applications which don't need a framebuffer may be able to use the second screen. And AFAIK such applications don't really need to be modified, since VC_DISPLAY variable can be used instead of --display argument for apps don't support such arguments. – Dmitry Grigoryev Mar 01 '17 at 11:25