jonnydmb
Posts: 3
Joined: Sun Apr 13, 2014 7:12 pm

HDMI output tvservice -p results in blank screen

Sun Apr 13, 2014 7:42 pm

Sorry, I'm new to all this - spent a few hours searching google as well as the forums here...

I'm trying to switch the screen connected to the Pi's HDMI port on and off via a python script.

tvservice -o works fine - the screen goes off.
tvservoce -p switches the screen back on, but it remains blank. The backlight goes on, but no display.

if I execute 'startx' from an SSH terminal (on a different computer) and then hit 'ctrl-x' the display comes to life...

How do I get this to work in the my python script?

I'm trying to replicate this tutorial:
https://github.com/samuelclay/Raspberry-Pi-Photo-Frame

... everything works except for switching the screen on and off...


Any help is greatly appreciated!


Best regards,
Andrew

jonnydmb
Posts: 3
Joined: Sun Apr 13, 2014 7:12 pm

Re: HDMI output tvservice -p results in blank screen

Thu May 01, 2014 11:27 am

... anyone have an idea on what could be going on here? Sadly, I'm still stuck! :-(

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DougieLawson
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Joined: Sun Jun 16, 2013 11:19 pm
Location: Basingstoke, UK
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Re: HDMI output tvservice -p results in blank screen

Thu May 01, 2014 11:36 am

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pibaldhorse
Posts: 1
Joined: Sun Nov 30, 2014 9:21 pm

Re: HDMI output tvservice -p results in blank screen

Sun Nov 30, 2014 9:42 pm

Novice here,
From what I read the blank screen after HDMI come back on seems to have something to do with the frame buffer getting stuck after tvservice -p turns the HDMI port back to the preferred HDMI settings.

Somehow CHANGING a setting using the fbset program will get the screen displaying content once again.

I changed my monitor_off.sh script to
fbset -accel false
tvservice -0

I changed my monitor_on.sh script to
tvservice -p
fbset -accel true

Thus before each time the port is turned off text acceleration in hardware is turned off and after the port is turned on the acceleration is turned on. I chose this setting to change because it seemed trivial.

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