Automatic overriding of configuration file in Raspberry Pi 2

Can config.txt file be overridden automatically during boot time? For HDMI and RCA cables we need different types of resolutions and there will be difference in audio configuration too. I want the config.txt file be overridden and loaded automatically at the time of booting and display features as per HDMI or RCA connections. Is it possible?

rew over 10 years ago

How do you want the override to happen? Keyboard input? Automatic detection of HDMI monitor?

You could write code that does that, and chooses between two variants of the config.txt depending on the presence of an HDMI monitor. This code would run on the graphics core: No compiler available, no specs, nothing.

What you could do is to have two config.txts: config.txt.hdmi, config.txt.rca and early in the boot process, if you detect you've been booted with the RCA config.txt, AND there is an HDMI monitor connected, you copy config.txt.hdmi to config.txt, and reboot. And of course the other way around.
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e14 Contributor over 10 years ago in reply to rew

How can I detect that it has been booted with RCA config.txt?
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rew over 10 years ago in reply to e14 Contributor

I would grep on fbheight=... in /proc/cmdline It is bound to be different for your RCA configuration. (probably 576 or something, a resolution I don't expect from an HDMI monitor).

With tvservice -d you can try to dump the edid data of the monitor, if that works, you probably have something connected... OK. I just tested that for you. My raspberry pi seems to remember the last monitor that it has seen. It happily dumps the EDID data of a monitor that is now connected to my other 'pi of which I pulled the power plug.

You'll have to look around for a trick to actually communicate with the monitor to detect the monitor.
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