Dual Displays: 7” Raspberry Pi Touch Screen and HDMI

Targets Raspberry Pi
1

I’m working on a project where I need dual displays on the Raspberry Pi (3). I’m testing with the 7" Raspberry Pi Touch Screen for the control panel and want to use the Pi’s HDMI for the extended desktop.

Apparently, this is not currently possible for X sessions. After reading many posts on this issue the summary I’ve found is that the app needs to be “aware of HDMI” and then can display video to it. Others have commented that you need to create another frame buffer and that the Pi’s firmware is the show stopper.

https://www.raspberrypi.org/documentation/hardware/display/troubleshooting.md

“At the moment you can’t use HDMI and the LCD together in the X desktop, but you can send the output of certain applications to one screen or the other.”

Audio to HDMI works. I’ve also tried increasing the Video RAM allocation to 128 MB, and still no luck.

Has anyone figured out how to push video from Xojo to the HDMI display port when using the Official Raspberry Pi Display?

2

I think you might be out of luck here, unfortunately - I suspect the restriction is the X desktop itself and Xojo can’t do much about it. omxplayer can do it because it doesn’t need to use the desktop environment. Could you use two Pis?

3

Thanks for the validation on this. Unfortunately using two Pis for what I need to do for this project won’t work. I’ll just end up using the Pi’s HDMI out and use an HDMI splitter and other hardware.