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For example, I want to output a 320x240 resolution to a composite monitor if no HDMI connection is found. Otherwise, output to HDMI as usual.

Is this possible? Can I edit something in config.txt or somewhere else? Can you use if-statements in config.txt?

quinten
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I don't think that is possible, config.txt is read by the bootloader with very limited resources. But please look at this posting - it gives you a good suggestion on how to do this using a GPIO-based VGA adapter: Multiple Display Screens

Community
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Phil B.
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Unfortunately, there's no way you could do this with built in functionality. The bootloader loads config.txt when the system starts, and once the system is up, that's it.

You could write a python/bash/ruby/whatever script that will swap out your config.txt config for a different one and restart the system. This of course assumes that restarting the system is an acceptable solution.

Jacobm001
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well... if you use either the composite or hdmi monitor (with useful tvservice -n-output) and the right one is already connected at the boot time (hotplugging won't change anything because the config.txt is read once at boot) you can probably use the [EDID=*]-filter in the config.txt!

please have a look at the real good Raspberry Pi documentation for the config.txt:
at the end there is a section about the filters (also the [EDID=*]-filter), and then you have to sort out your desired configurations for your hdmi monitor... the [all]-settings will be for the composite.

if you are not using always he same hdmi monitor you have to try multiple [EDID=*]-filters.

DJCrashdummy
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