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Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

johnlian.net

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Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#31

Post by zimpenfish »

codepoet80 wrote: post #4

Yup, my AppleTV is the only device that gets CEC right. Even my LG TV and LG soundbar get confused. And don’t get me started on the PS4 Pro’s garbage implementation. I’m sad that Logitech killed Harmony because CEC was supposed to make universal remotes obsolete — they’re still the only way my full home theater can function without juggling a dozen remotes.

Amusingly, my AppleTV is currently the one thing that doesn't even though it used to - for some reason, with no changes, it just stopped turning on the TV. Switch 2 can happily turn on the TV though. Most peculiar.

(I've tried updating the AppleTV, replugging the HDMI cable, unplugging the HDMI cable for , etc. Nothing has worked. TV does not have any network which means it can't have had any nefarious updates.)

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#32

Post by rgovostes »

This is the lord’s work. It’s ridiculous that in 2025 my $500 gaming PC GPU cannot tell the receiver to change inputs. Even my Apple TV, which is considered a model citizen here, steals the receiver’s input every few hours if I have another device active.

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#33

Post by extraduder_ire »

tylerflick wrote: post #8
jauntywundrkind wrote: post #6

I know it's called a bus, but I'm still surprised that all devices get the HDMI-CEC stream of all other devices. Being able to watch the Apple TV from the Pi was super cool, and I never would have guessed it was possible to see what was going on there (short of building a man in the middle hardware proxy)!

CEC is just i2c which is a bus. In fact you can hook regular i2c devices up to an HDMI port and communicate with them. You’ll need a resistor and shouldn’t draw more than 50 mA.

It's electrically similar, but not directly compatible. (if you know better than me, please let me know)

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#34

Post by monster_truck »

recursive wrote: post #17

Modern AV stuff is insane. I have no interest in taking it up as a hobby. I have an xbox, a TV, and a pair of bookshelf speakers. How am I supposed to get the audio to the speakers without a bulky expensive receiver box? Luckily, I have one of the last remaining TVs with a headphone jack. I don't use a remote for any of it. Side note: Sometimes the TV doesn't come on when you press its power button. After a tremendou…

It's still very simple and you have never needed anything expensive to do so. Stop with the learned helplessness and "being afraid to try a new TV"

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#35

Post by extraduder_ire »

amluto wrote: post #9
tylerflick wrote: post #8

Earlier quoted context omitted.

CEC is just i2c which is a bus. In fact you can hook regular i2c devices up to an HDMI port and communicate with them. You’ll need a resistor and shouldn’t draw more than 50 mA.

I always assumed that it was a separate i2c bus per HDMI link and that it was the AVR’s job to handle a request from something and send the right requests to everything else.

Much like i2c, any message put on the bus is transmitted to everything on the bus.

Version 1.0 and later of the HDMI spec even mandate that you have to connect those pins across all HDMI ports on your device even if you don't do anything with them.

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#36

Post by crtasm »

codepoet80 wrote: post #4

Yup, my AppleTV is the only device that gets CEC right. Even my LG TV and LG soundbar get confused. And don’t get me started on the PS4 Pro’s garbage implementation. I’m sad that Logitech killed Harmony because CEC was supposed to make universal remotes obsolete — they’re still the only way my full home theater can function without juggling a dozen remotes.

Anyone know how to make a LG TV wake an AppleTV from sleep?

Once it's awake buttons presses on the LG remote are passed through to it but I have to keep the Apple remote around for that first step.

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#38

Post by waerhert »

tylerflick wrote: post #8
jauntywundrkind wrote: post #6

I know it's called a bus, but I'm still surprised that all devices get the HDMI-CEC stream of all other devices. Being able to watch the Apple TV from the Pi was super cool, and I never would have guessed it was possible to see what was going on there (short of building a man in the middle hardware proxy)!

CEC is just i2c which is a bus. In fact you can hook regular i2c devices up to an HDMI port and communicate with them. You’ll need a resistor and shouldn’t draw more than 50 mA.

Isn't DDC the I2C bus? Interesting article about that here: https://mitxela.com/projects/ddc-oled

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#39

Post by rhinoceraptor »

recursive wrote: post #17

Modern AV stuff is insane. I have no interest in taking it up as a hobby. I have an xbox, a TV, and a pair of bookshelf speakers. How am I supposed to get the audio to the speakers without a bulky expensive receiver box? Luckily, I have one of the last remaining TVs with a headphone jack. I don't use a remote for any of it. Side note: Sometimes the TV doesn't come on when you press its power button. After a tremendou…

Another infuriating issue is TVs with so few HDMI inputs. I have tried many different HDMI switchers and none of them work reliably, so it kind of puts me off of buying a receiver which would also have that function.

Re: Fix HDMI-CEC weirdness with a Raspberry Pi and a $7 cable

#40

Post by davidczech »

A side note: I am very sad that HDMI-CEC apparently can only support like 3 "console-like" devices. I have an Apple TV, Nintendo Switch 2, Sound Bar (eARC) and PS5 hooked up, but only 3 can really interact with CEC.

It took me a long time to diagnose why it seemingly wouldn't work with my Nintendo Switch 2.

I ended up disabling it on my PS5 because I never use the darn thing, but it kind of stinks since most TV's have 4 HDMI inputs.

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