RossDv8
Posts: 260
Joined: Thu Jan 21, 2016 12:35 pm

Why does my Raspberry Pi turn my TV ON ?

Thu Sep 16, 2021 5:56 am

I'm curios about this - but it is NOT a problem.
When I switch my Raspberry Pi 4B on in the morning, a few moments later, my monitor (a 55 inch TV connected to the Pi via HDMI) switches ON, and moments after that, my Pi desktop appears.

None of my other computers connected to the TV do this - only the Pi. I don;t remember the older Pis doing this, but I'm pretty sure they were connected to a 50 inch TV.

Anyway, it is interesting behaviour. On one hand, there's one less button to press in the morning, or one remote I don't have to find, so it is a good thing. On the other hand - if I could teach one of the other two computers connected to the TV to do this trick, I would not have to turn anything on, because they can be programmed to start and shutdown automatically each day in BIOS (as most computers can). Sadly, I don;t hink there's a practical way to do that with the Pi because there's no BIOS.

Afterthought. I could use a timer switch to turn the Pi on each day, and a cron job to shut it down.

So the main thing is - has anybody else noticed that if they boot their Pi4B with a HDMI TV (or monitor) plugged in, but switched off, that the Pi turns the monitor ON?
(Obviously the TV is in standby waiting for a signal from the remote)
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drgeoff
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Re: Why does my Raspberry Pi turn my TV ON ?

Thu Sep 16, 2021 7:23 am

Search Wikipedia for 'CEC'.
Quis custodiet ipsos custodes?

RossDv8
Posts: 260
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Re: Why does my Raspberry Pi turn my TV ON ?

Thu Sep 16, 2021 7:58 am

Magic ! Thanks.
So If I'm understanding the Wikipedia article correctly, my TV has CEC enabled and somehow the Raspberry Pi can interact in a way that wakes the TV from standby, just as if I picked up the remote and hit the Power Button on the remote.

I'm still fascinated that the Pi can do this by default, but that not one of my other computers has this feature enabled !

My next projext obviously will be to boot all my other computers into the BIOS screen, and start searching for CEC.
In the mean time then, I'll just happily enjoy using the Pi to turn on my TV / Monitor.

Thanks again drgeoff :D

RossD
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DougieLawson
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Re: Why does my Raspberry Pi turn my TV ON ?

Thu Sep 16, 2021 8:28 am

RossDv8 wrote:
Thu Sep 16, 2021 7:58 am
I'm still fascinated that the Pi can do this by default, but that not one of my other computers has this feature enabled !
You can disable CEC with a line in /boot/config.txt to stop the boot up action.

Code: Select all

hdmi_ignore_cec_init=1
Or

Code: Select all

hdmi_ignore_cec=1
To completely disable the CEC function.

Docs here: https://www.raspberrypi.org/documentati ... e_cec_init
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ganzgustav22
Posts: 253
Joined: Tue Feb 11, 2020 1:04 pm

Re: Why does my Raspberry Pi turn my TV ON ?

Thu Sep 16, 2021 9:12 am

Yeah, the CEC functionality of the Raspberries is really nice. Just put in LibreElec, connect the Pi to your TV (without any keyboard or mouse connected) and happily use your TV's remote control to navigate through LibreElec/Kodi.

RossDv8
Posts: 260
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Re: Why does my Raspberry Pi turn my TV ON ?

Fri Sep 17, 2021 1:12 am

People in various places (on forums) ask 'can a Raspberry Pi replace my Desktop PC.
Looks like it can (at least the 8GB version of Pi4B), and according to the previous repl;y it might be able to be a complete little entertainment box.

I was concerned that this 'turning on the TV' thing might be related to my running the Pi from a 5A USB C power adapter, but I remembered it has done it from day one.

Again - thanks for the answers.

Now I need to scour the BIOS of my other machines to see if they contain the same ability. Although, with the Pi able to turn the monitor that's shared by all 3 computers, I will probably never use it. :)
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dustnbone
Posts: 518
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Re: Why does my Raspberry Pi turn my TV ON ?

Fri Sep 17, 2021 3:54 am

They will pry my LibreELEC Pi4 from my cold dead hands.

This is actually how I realized it had CEC support, so I grabbed my TV remote and sure enough it just worked. The xbox 360 controller is still a better remote but it's nice not always having to figure out where I lost it.

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