> I still don't entirely understand how HDMI/CEC knows what my monitor is. It feels like the monitor is powered off, does the chipset respond to the voltage sent "up" the HDMI lead?
Yes. The HDMI source provides 5V over pin 18.
The same mechanism is also used in VGA and DVI.
Re:“Just turn it off” and Airplane Mode
by theshrike79 on Monday June 19, 2023 @12:58AM
(#36387456)
> If you really want devices you can turn off, you may want to back the EU initiative to return to a time of replaceable batteries.
Just to clarify, the EU initiative isn't for the 90's style batteries you can just carry 5 with you and swap when they run out. It's purpose is to make swapping batteries not require special tools like pentalobe screwdrivers or specific tools to heat components.
I don't mean the battery backup RTC. I mean that in order to do things like "wake on lan" they simply have to be partially "on" in some ways. Colloquially they are off. They are not electrically off, or isolated from functional systems which know how to do some things.
(obviously, phones do not normally expect to be connected via RJ45 into a network which implements the wake-on-lan and IPMI)
If you remove their main batteries, they become much more really "off" -if you don't have an external source of power attached.
I still don't entirely understand how HDMI/CEC knows what my monitor is. It feels like the monitor is powered off, does the chipset respond to the voltage sent "up" the HDMI lead?