[HN Gopher] The smallest and worst HDMI display
___________________________________________________________________
The smallest and worst HDMI display
Author : todsacerdoti
Score : 607 points
Date : 2022-03-31 16:31 UTC (6 hours ago)
(HTM) web link (mitxela.com)
(TXT) w3m dump (mitxela.com)
| samstave wrote:
| Kinda unrelated, but I wish there were an HDMI std which also
| included power.
|
| I have two AOC 15" USB ONLY screens that I use with my laptop,
| and they all fit in my backpack...
|
| So I have a 3-screen setup in my backpack with one power supply
| (the laptop) ... its such a sweet setup.
|
| but an HDMI+power would be great (because then I could also have
| audio, and free up my USB ports.)
| detaro wrote:
| I guess the answer for that nowadays is "USB-C", will all the
| complexity included with that...
| lostgame wrote:
| These kinds of fantastic hackery are the reason I consistently
| come back to HN. This is an absolutely fascinating little piece
| of kit.
|
| It begs the question to as if there would be any actual utility
| to a display this small with it having to be directly attached to
| the laptop.
|
| Smartwatches come to mind, but tethered smartwatch-size
| displays...hmm...maybe add a wi-fi module and we've got
| something?
| st3ve445678 wrote:
| But can you play Doom on it?
| bskrobisz wrote:
| I'm sure that those with a lot more hardware experience than me
| have the intuition to make guesses like this but I was surprised
| at:
|
| >You have to register to download the HDMI spec which is more
| effort than I have for this, but the Hot Plug Detect pin has a
| pretty descriptive name. I guessed that this either has to be
| pulled up or pulled down to signal that a cable is connected.
| Sticking a 20K resistor to the 5V pin seemed to do the trick.
| With the oscilloscope, we can now see activity on the SCL/SDA
| lines when it's plugged into the laptop.
|
| Is it really not that concerning to just guess what amperage
| will/won't fry something? I mean, you could test from very high
| resistances downwards, but you might overshoot, right? Or is
| there an assumption that the hardware on either end will provide
| the appropriate resistance, in this case?
| [deleted]
| makach wrote:
| omg, i just bought and installed this display for my rpi4 and you
| tell me I can use it as a second monitor!? this is why I am a
| tech geek. :heart:
| jrockway wrote:
| You don't need to go through all the steps involving HDMI.
| Linux can create framebuffers on I2C/SPI displays like this.
| Many years ago, I connected two to a Beaglebone and it ran
| Emacs just fine. Much device tree hacking is involved, though,
| unfortunately.
| makach wrote:
| yes, yes, this is exactly what I did. But connecting it to an
| HDMI port is infinitely much more cooler!
| technothrasher wrote:
| This isn't so much an HDMI display as an I2C display utilizing
| the DDC channel in the HDMI interface as the I2C bus. I've seen
| folks utilizing this on the Raspberry Pi as a generic I2C bus as
| well.
| hunter2_ wrote:
| Eh, that's like saying phones don't charge over USB, just DC.
| We're referring to the physical connector more than to the
| typical bus.
| IshKebab wrote:
| Yeah I dunno, when I started reading I thought he had found a
| display that was coincidentally HDMI-compatible with the
| display HDMI signals.
|
| It's at least misleading.
| Evidlo wrote:
| Its not quite the same. I don't need to download a special
| host script to charge my phone on a friend's computer.
| amelius wrote:
| I'm looking for a UART monitor with slightly bigger screen, and
| baudrate autodetection, to be used for debugging. It should be
| cheap.
|
| Any ideas where to look?
| threeme3 wrote:
| http://www.technoblogy.com/show?TV4
| mfwit wrote:
| What a lovely little collection of small projects.
| throwntoday wrote:
| Oh wow, I remember this guy from a Zelda forum I was on nearly 20
| years ago. Glad to see he's still around.
| madeofpalk wrote:
| What great timing. I've rearranged my desk and have trouble
| fitting a second monitor next to my ultrawide + big speakers, and
| I've been looking for a smaller monitor.
|
| This might be a tad too small, but worth considering!
| Unit520 wrote:
| Very cool hack indeed! One thing I learned from this is that
| having an HDMI port gives you a free I2C port on top as well, as
| long as you have an old HDMI cable lying around to cut open.
|
| Small note on using these OLEDs with 5V: Typically they expect
| 3.3V Vcc and logic levels, although almost all of them seem to
| work just fine with 5V. In my experiments with a regular 5V
| Arduino some OLED modules made weird coil whining noises, I
| presume this is from the charge pump circuitry. Driving them with
| 3.3V as specified removed the coil whine completely.
| gotaquestion wrote:
| To me the cool part is that you get a free I2C output over an
| HDMI port.
|
| I don't know any laptops that have native I2C output w/o a USB
| converter.
| blamazon wrote:
| Link to the video demo at the end of the article:
|
| https://youtu.be/8UbVgUFfN8U
| ironmagma wrote:
| Side note, "Look around you" is an allusion to this video
| series:
|
| https://www.youtube.com/watch?v=t4CRCJUmWsM&list=PLsMUa0l1PW...
| blamazon wrote:
| Write that down in your copy book now.
| ByThyGrace wrote:
| > You have to register to download the HDMI spec which is more
| effort than I have for this
|
| Wait, what? Register where? Is the HDMI spec behind IP bars?
| stretchwithme wrote:
| 20 years ago, we came across this tiny CRT display. I think it 4
| X 5 inches. We pranked a coworker with it, replacing her large
| display with this tiny thing.
|
| And left a note explaining how the black and white display was an
| upgrade. :-)
| stretchwithme wrote:
| I think we claimed it was an upgrade because it saved wear and
| tear on her rods and cones.
| InCityDreams wrote:
| A colleague of mine pranked a (much liked) co-worker: police
| and an anti-terrorism squad were called. Hilarity ensued....
| goodburb wrote:
| This is pretty useful for NUCs, Qotoms, and x86 routers for
| showing stats.
| mjlee wrote:
| > Here is some trivia: did you know that the mouse cursor is
| rendered by hardware?
|
| Ah! That perhaps explains why often the cursor moves around just
| fine when other elements of the stack have completely given up.
| MayeulC wrote:
| As far as I know, it isn't really rendered by HW, but
| _composited_ in HW.
|
| GPUs usually have multiple "Hardware planes" that are
| composited together in hardware before sending the signal. The
| OS is free to put whatever it wants there. Most HW include a
| designated "cursor plane", but it could be used to display
| whatever.
|
| IIRC a minimum of 3 HW planes is specified somewhere, it could
| be the Wayland protocol, or the Linux Direct Rendering Manager
| API. Some devices can have less though. That would be the case
| for that display, which could use an actual framebuffer driver
| (although planes could be emulated).
|
| You can thus have a layer for the background, one for the
| windows, and one for the cursor, and avoid re-painting too
| often, even though it should be pretty cheap for GPU-
| accelerated surfaces (like with compositors that rely on
| OpenGL).
| iforgotpassword wrote:
| I recently learned about evdi, an out of tree Kernel module that
| can add as many virtual outputs as you want. Ideal for things
| like this, or where you'd normally use a dummy plug.
| phh wrote:
| Article makes fun of how slow i2c is compared to the super high
| speed pairs next to it on HDMI plug. Well, please note that there
| is a bus that is literally a thousand time slower than i2c on
| that same connector. It's CEC. Contrary to i2c it only occupies
| one wire rather than two though. CEC, which is used mainly to
| power TV on/off or switch sources has a whopping bandwidth of
| 400bps. No missing multiplier.
|
| Maximum device name is 16B. If you have a TV, a tvbox and a game
| console, simply asking the name of those devices can take more
| than a second. I'm in the process of shortening my product's CEC
| name, in order to reduce congestion on the bus.
|
| Mainline Linux CEC developer jokes that Voyager 1 which is on the
| other side of solar system, made 40 years prior to CEC, is faster
| than CEC.
|
| Edit: Sorry for the atrocious original formating
| babypuncher wrote:
| You sound like you know a lot about the HDMI CEC spec. Do you
| have any insight as to why CEC implementations are often buggy
| on so many devices? I.E. "one touch play" turning on unintended
| devices in addition to your display and receiver.
| phh wrote:
| First, I have to plead guilty: my own product's CEC still has
| many "simple" flaws.
|
| That being said, I indeed have the feeling that CEC is
| specifically badly implemented by most people.
|
| I feel like the standard is rather under-specified (or there
| are things I don't understand), like it's said how some kind
| of devices are supposed to behave based on some commands, but
| no explanation as to how other devices are supposed to behave
| on those commands.
|
| For instance, it is specified that a Player (there are
| various types of devices in CEC, more on that later) can send
| an AVR (which is different kind of CEC device, there can only
| be one in the whole network) volume commands. More
| specifically, a Player can send an AVR VOL+ and VOL- key
| presses to change volume. What happens if you send VOL+/VOL-
| to a TV? That's not specified until 2016 with CEC 2.0. So you
| can't control volume on most TVs if you don't have an AVR.
|
| The number of "slots" available per device kind is constant:
| exactly one TV, exactly one AVR three players, 4 tuners, 3
| recorders. You have a tvbox, and three game consoles (all
| shold be Players)? Well someone will have to lie and become a
| tuner or a recorder, or they won't be allowed on the bus.
|
| Another thing that makes this messy, is that CEC needs to fit
| in small power budget during suspend. For instance, in
| Europe, the legal power budget in sleep is 0.5W. This means
| that your main application processor can't handle CEC in
| suspend. Usually, this leads to multiple "concurrent" CEC
| stacks, running in different CPUs, switching from always-on
| Cortex-M, to full-blown Cortex-A (and then you add Android TV
| on top of that with its own CEC stack, and you get three CEC
| stacks co-working together). Often the communication pipeline
| between those people is pretty light, and going through all
| those layers, you might end up losing the info of whether the
| wakeup instruction came from your remote (so you legit want
| to have the TV wake to you), or from CEC (so you want to let
| TV decide of the output).
|
| I believe one gigantic factor is that CEC has started very
| poorly (no matter the reason), and since then,
| interoperability problem has been considered by most QA as
| "yeah well, this is life"
|
| Back specifically to your question "I.E. "one touch play"
| turning on unintended devices in addition to your display and
| receiver.": This is very very usual. I don't know what the
| specs say precisely, on the matter, but here's what I
| witnessed on many TVs (many enough that I expect this to be
| the standard, but it's possible it's related to what I said
| earlier about dual-stack):
|
| - Say you have HDMI1 and HDMI3 devices connected, you
| suspended TV on HDMI1, you wakeup from HDMI 3.
|
| 1) On wakeup, TV sends Set Stream Path to the previously
| selected device. If you suspended your TV on HDMI1, and
| you're waking up from HDMI 3, TV will start with a Set Stream
| Path to say "hey, the screen I'm currently displaying is HDMI
| 1".
|
| 2) HDMI1 device listens, and wakes up. In the process of
| waking up, it needs to tell the TV it is ready with
| ACTIVE_SOURCE command, so they do.
|
| 3) If HDMI3 is in the "clever" range, HDMI3 will send again
| "Please TV switch to HDMI 3" with ACTIVE_SOURCE
|
| 4) Even if HDMI3 isn't in the "clever" range, TV will later
| send Set Stream Path to HDMI3, because it remembered HDMI3's
| command to wake up to them, or because of thanks to -3-
|
| 5) Everyone's happy, TV's on HDMI 3
|
| 6) Message sent in -2- finally manages to reach the bus more
| than one full second later, because HDMI1 is less aggressive
| on CEC bus than the other.
|
| ... And there you go, TV switches back to HDMI 1.
|
| Fixing this is possible, HDMI 1 "just" needs to cancel -2-
| when seeing -3- or -4-, but most CEC implementation's
| send_pkt doesn't include cancellation signals. So, it's
| possible to make better CEC implementations (though it
| requires mechanism that are pretty complicated for an
| embedded world), but I don't think it's possible to make a
| perfect implementation that will never miss.
| MayeulC wrote:
| Thank you for your detailed answer!
|
| At times, I regret DisplayPort not having something
| comparable (it has data channels, but nothing "as well
| specified" as CEC for controlling other devices). I think
| you explained part of the reason. If it were specified, it
| would require careful consideration, and probably a
| conformance test suite. I still fully expect manufacturers
| to try to re-brand it, extend it themselves, and generally
| botch their software like they end up doing most of the
| time.
| babypuncher wrote:
| Wow this is pretty detailed, and makes a lot of sense. It's
| a shame the standard does not seem more well thought out.
|
| One solution I've always felt would be handy would be for
| devices to have an option to ignore any CEC commands that
| would normally cause them to wake. As it is right now,
| everything is so buggy between my LG TV, Yamaha Reciever,
| and "players" that I have to disable the feature entirely
| on either my PS5 or Apple TV in order for things to not go
| haywire.
| unwiredben wrote:
| Also in play is that some parties have patents on certain
| kinds of control systems using CEC, so just implementing
| something that seems useful can get a device manufacturer
| in legal trouble :(
| clairity wrote:
| mine works decently, except something seems to often be
| sending an errant 'on' signal to my a/v receiver: i hit the
| power button (on any remote) and everything turns off (as i
| want), only for my receiver to wake up 1-5 minutes later (my
| dvd/blu-ray player also comes on for a second, but then turns
| off automatically). super annoying.
| deltarholamda wrote:
| TIL what the hell was happening when I turned on my TV and
| the receiver usually switches to the wrong device.
|
| I'm just glad I'm not crazy.
| ziml77 wrote:
| I wish they'd made CEC a little more powerful. I like that I
| can control my AV receiver's volume with the TV remote, but I
| don't like that I can't see what the volume is actually set to
| on the TV. Even if I had a receiver that could overlay onto 4K
| video, that wouldn't help for the cases where I'm feeding audio
| back from the TV to the receiver.
| anthk wrote:
| I played Slashem and edited files with ed(1) over 600bps. Not
| bad, but things start to get usable enough at 9600 BPS.
| m463 wrote:
| > CEC, which is used mainly to power TV on/off
|
| in my experience it doesn't even do that very well. I tried
| getting a raspberry pi to power off an attached display and
| support of on/off seems to be hit or miss and specialized.
|
| I suspect it isn't supported because it will commoditizes the
| device, when manufacturers really want their own protocol that
| connects only to their own products.
|
| much better sales of acme products if an acme tv can only
| connect to an acme soundbar and an acme dvd player using acme
| protocols.
| colejohnson66 wrote:
| Voyager is so far away that it's estimated data rate is only a
| hundred or so bps.[0] So CEC is actually faster now than
| Voyager! New Horizons still has the edge with an estimated
| kilobit/sec.
|
| EDIT: I was partially correct. It seems Voyager can transmit at
| up to 1.4 kbps for certain things.[1]
|
| [0]: https://space.stackexchange.com/questions/24338/how-to-
| calcu...
|
| [1]: https://voyager.jpl.nasa.gov/mission/spacecraft/
| satsuma wrote:
| well, problem solved then! no need to update cec anymore
| akira2501 wrote:
| Realtime status of the Deep Space Network:
|
| https://eyes.nasa.gov/dsn/dsn.html
| dr_orpheus wrote:
| Voyager still actually gets up to a whopping 1.4 kbps
| downlink! (but only 16 bps uplink)
|
| https://voyager.jpl.nasa.gov/mission/spacecraft/
| perihelions wrote:
| That's a bit confusing; shouldn't it be the other way
| around? Because they're using the same antennas in both
| directions, but the power budget on the Earth-transmitting
| side is much higher.
|
| (Asked in the spirit of curiosity; I'm ignorant of radio
| physics).
| NikolaNovak wrote:
| I'm assuming that our ability to computationally aid /
| resolve signal is far higher than voyager's.
| squarefoot wrote:
| > CEC, which is used mainly to power TV on/off or switch
| sources
|
| CEC is much more than that as it allows the use of a single
| remote instead of two or more, which is super handy; the TV
| remote sends its commands through the HDMI cable to the active
| device, so if you switch from TV to an external source like PVR
| or media center on the TV remote, if that device supports CEC
| (Kodi on a Raspberry PI does that) you can control it
| seamlessly through the TV remote. I recently switched my media
| center from a Raspberry PI 4 to an older (but much faster)
| unlocked Chromebox whose video chipset doesn't support CEC, so
| I had to connect an external interface that does USB to CEC
| conversion. Unfortunately there is only one manufacturer of
| such interface, which means it's not that cheap.
| https://www.pulse-eight.com/p/104/usb-hdmi-cec-adapter
| exikyut wrote:
| That USB to CEC passthru box is $44.92 for reference. I do
| wonder what chipset it's using under the hood to do its
| thing, but given the combination of HDMI licensing/royalty
| fees, manufacturing tooling, the little custom enclosure it
| has (looks like molded/formed plastic, if I'm using the right
| term), then factoring in the low production volume, and
| considering that this seems to be a smaller operation... I
| think it's quite plausible the margin on the thing is quite
| small. Very plausible.
|
| While on the page I was curious if the firmware was open
| source. While writing this and properly articulating the bit
| about HDMI royalty (and also just now realizing it might need
| to deal with HDCP... ah) I now realize the question is moot,
| but I didn't think of any of what while looking at the
| webpage, so I wondered if it would be interesting to have a
| cursory poke at the firmware download.
|
| 7-Zip (also available as a commandline program as p7zip-full
| on debian et al) is honestly grossly understated it its
| capabilities. I didn't feel like remembering how to invoke
| binwalk so tried `7z x firmware-v7.exe` almost as a bit of a
| challenge and it _actually worked_ :) $ 7z l
| ~/Downloads/firmware-v7.exe Path =
| /home/i336/Downloads/firmware-v7.exe Name =
| WEXTRACT.EXE .MUI OS Version = 6.1
| Image Version = 6.1 Subsystem Version = 5.0
| Subsystem = Windows GUI DLL Characteristics = Relocated
| NX-Compatible TerminalServerAware Comment =
| FileVersion: 9.0.8112.16421 FileVersion:
| 9.00.8112.16421 (WIN7_IE9_RTM.110308-0330) CompanyName:
| Microsoft Corporation FileDescription: Win32 Cabinet
| Self-Extractor
| ---- Path = .rsrc/RCDATA/CABINET Type = Cab
| Physical Size = 1348694 ID = 7086 Date
| Time Attr Size Compressed Name
| ------------------- ----- ------------ ------------
| ------------------------ 2016-04-13 13:05:12 ....A
| 184800 flash.exe 2012-08-29 16:19:56
| ....A 619536 driver1.exe 2012-02-21
| 04:24:52 ....A 816224 driver2.exe
| 2012-07-31 15:35:30 ....A 400
| flash.cmd 2012-03-10 11:27:28 ....A 67008
| libusb0.dll ...
|
| It output even more lines of metadata than I included. I
| removed probably 50% of output so as not to spam the
| subthread.
|
| Awesome.
|
| Hmm... what if I do the same to `flash.exe`?
| $ 7z l flash.exe ... Linker Version = 10.0
| OS Version = 5.1 Image Version = 0.0 Subsystem
| Version = 5.1 Subsystem = Windows CUI DLL
| Characteristics = Relocated NX-Compatible TerminalServerAware
| Date Time Attr Size Compressed Name
| ------------------- ----- ------------ ------------
| ------------------------ ...
| ..... 67392 67392 .rsrc/RCDATA/101
| ..... 2496 2496 .rsrc/RCDATA/102 ...
| ------------------- ----- ------------ ------------
| ------------------------ 2016-04-13 22:05:07
| 183568 183568 9 files
|
| _HMMmmmm_ , RCDATA you say?
|
| Extracting (`7z x ../flash.exe` from an empty subdir)
| produced newline-less ASCII hex output
| ("EF19541A19D258B099B877545DE0B65BBBC5602..."), so after a
| bit of `printf "$(cat 101 | sed 's/../\\\x&/g')" > 101.bin` I
| came up with... nothing.
|
| Binwalk has no idea what it is. Perhaps the start of the
| files ring bells for some humans? $ ls -l
| -rw-r--r-- 1 i336 i336 67392 Apr 13 2016 101 -rw-r--
| r-- 1 i336 i336 33696 Apr 1 05:46 101.bin -rw-r--r-- 1
| i336 i336 2496 Apr 13 2016 102 -rw-r--r-- 1 i336 i336
| 1248 Apr 1 05:48 102.bin $ xxd 101.bin | head -n
| 5 00000000: ef19 541a 19d2 58b0 99b8 7754 5de0 b65b
| ..T...X...wT]..[ 00000010: bbc5 6020 54e7 ca9a 1fb7
| beca 0a39 95c4 ..` T........9.. 00000020: c876 de8a
| 4705 19a5 9f03 4c56 5d83 9550 .v..G.....LV]..P
| 00000030: f5ad 2930 5f07 9b46 21b1 91a0 d091 4685
| ..)0_..F!.....F. 00000040: 3ada 0ce3 305b 49e1 939e
| 7384 3c5a 5794 :...0[I...s.<ZW. $ xxd 102.bin |
| head -n 5 00000000: f3f1 7b55 3f33 cbed 426e 1ab7 5792
| 4425 ..{U?3..Bn..W.D% 00000010: 8e75 1566 5597 8183
| c1ce 9265 6acf 3b73 .u.fU......ej.;s 00000020: 1370
| 47b4 5431 399b f73f 0f6a 6323 3329 .pG.T19..?.jc#3)
| 00000030: 0e52 25ad 0530 5d03 9393 bc8c 40c8 f0fb
| .R%..0].....@... 00000040: c63c 7ddb 4d3a cd89 ab4a
| e6c7 cb2f ab4f .<}.M:...J.../.O
|
| For what it's worth, having realized this might be touching
| HDCP or for all I know might be an FPGA bitstream, I
| emphasize my interest is purely coming from a decidedly non-
| exhaustive sense of "ooh that's a cute product, I wonder what
| firmware it runs and how it broadly works internally"
| entirely made up of idle curiosity :)
| squarefoot wrote:
| Unpacking the files also produces a certificate, and the
| strings command on the flash.exe executable reveals also
| references to various related links, so it is possible that
| the firmware is also encrypted and signed.
| --- http://s2.symcb.com0
| http://www.symauth.com/cps0(
| http://www.symauth.com/rpa00
| http://s1.symcb.com/pca3-g5.crl0 SymantecPKI-1-5670
| Symantec Corporation1 Symantec Trust Network100.
| Symantec Class 3 SHA256 Code Signing CA ---
|
| ... etc.
| aidenn0 wrote:
| The intel NUC exposes the CEC pins to the motherboard, and
| the same company makes an internal USB/CEC adapter for $15
| less[1]. That PCB is almost entirely an MCU and a crystal,
| so the plastic box and HDMI passthrough adds $15.
|
| 1: https://www.pulse-eight.com/p/154/intel-nuc-hdmi-cec-
| adapter
| exikyut wrote:
| Ah, I see.
|
| The listed photos are _just_ at the wrong angle to be
| able to read the chip markings (grr)... but I had a bit
| of a further poke around, and found a listing for a
| discontinued internal board for HTPC (!) setups:
| https://www.pulse-eight.com/p/117/internal-hdmi-cec-
| adapter
|
| A reasonable bit of eye-strain later I at last identified
| that I was staring at an AT90USB162-15AU. Here's a
| reference for the -16AU:
| https://www.mouser.com/ProductDetail/Microchip-
| Technology-At...
|
| Huh. 16MHz. That answers that then.
|
| (Now I'm a tad _more_ idly curious why the firmware was
| unreadable.)
| MayeulC wrote:
| HDCP is unrelated to the CEC bus. CEC is completely
| separate and unencrypted. The pulse-eight adapter, AFAIK,
| should just be a female-female connector with two pins
| plugged into a microcontroller.
|
| I've toyed with the idea of replicating its functionality
| on an Arduino, but ended up just buying the adapter :)
|
| In the end, I'm not sure how doable it is, but it shouldn't
| be too complex. Licensing is another matter. I'm at a loss
| as to why GPU makers don't wire it up though.
| exikyut wrote:
| I see (TIL a lot about CEC, added some info to a sibling
| comment).
|
| I incidentally found
| https://hackaday.io/project/168696-cec2usb while poking
| around, last updated a couple years ago so probably not
| available for sale anymore, but open source at least.
| post-it wrote:
| Oh neat, I assumed my PVR remote just had an infrared emitter
| that controlled the TV at the same time as the PVR.
| phh wrote:
| Yes, CEC can do much more, but IMO the basic requirement is
| to power TV on/off properly and control volume, so that I can
| use whichever HDMI device's remote alone. Everything should
| be extra.
|
| But yes it can do much more: You can program records over
| CEC! You can directly select broadcast service! (i.e. not
| just through key presses, but indeed say which channel you
| want) You can display some message on TV's OSD! You can
| discover another device's language! You can make audio 0.1%
| or 0.01% slower (or 1% and 0.1%? I don't remember)
|
| I don't think I've crossed any device that supports any of
| the command I just mentioned however.
|
| Though "Dispay some message on TV's OSD" from CEC bus would
| be perfectly on point based on TFA.
| HNHatesUsers wrote:
| philistine wrote:
| Some surprising companies have not completely figured out the
| correct way to use CEC either.
|
| - Apple: When you start an Airplay stream on your phone
| directed at an Apple TV, the Apple TV doesn't send a _switch
| input_ command.
|
| - Nintendo: The Nintendo Switch _switch input_ command when
| waking from sleep is unreliable at best.
|
| - Microsoft: Surprisingly the worst offender. The only
| _switch input_ command it ever sends is when it wakes from
| user-induced sleep. If you let the console go to sleep on its
| own, and wake up the controller and press the big Xbox
| button, it never sends a CEC command.
| pjerem wrote:
| I solved the switch input issue by using an automatic HDMI
| switch from Aliexpress. This thing is remarkably reliable
| at switching to any source that starts emitting a signal.
|
| I don't know if there are switches capables of turning on
| and off the TV based on the presence or lack or signal but
| that could be the ultimate solution to this issue.
| tinus_hn wrote:
| What is the purpose anyway? Why would a device send a
| signal to turn on the tv through an HDMI connection,
| without tuning to that HDMI channel?
|
| That seems to be the main use case, but instead the design
| forces every source to be a universal remote control.
| satori99 wrote:
| I use my chromecast to turn my TV on or off with voice
| commands, even when I just want to watch FTA channels.
| tinus_hn wrote:
| So you use your device as a universal remote control.
| That is not at all the common use case.
| theturtletalks wrote:
| People reading this, make sure to enable it in settings.
| Thought my TV didn't have HDMI-CEC, but it was deep in the
| settings and unchecked by default.
| pjerem wrote:
| Also, I don't know if it changed since I no more have a
| TV but on my last TV, HDMI CEC was both disabled by
| default but also renamed with some stupid marketing
| feature name TV manufacturers are capable of like
| SmartLink or some shit like this. BTW, it was a LG TV
| before WebOS.
| squarefoot wrote:
| Yes, some manufacturers give CEC a different name for
| added confusion; on LG sets it is called SimpLink. The
| Wikipedia page reports them.
|
| https://en.wikipedia.org/wiki/Consumer_Electronics_Contro
| l
| ByThyGrace wrote:
| Some years ago I set to be able to control my smart TV
| via my laptop. Unfortunately, the graphics card
| (integrated or discrete) must also support the CEC spec
| in order to be able to send commands to the TV. Having a
| HDMI cable is not enough. My laptop did not ship with
| that requirement.
| BoorishBears wrote:
| Having worked on a large product that plugs into TVs and
| uses CEC, I wouldn't be so quick to blame the devices as I
| would be to blame your TV...
| dhritzkiv wrote:
| > When you start an Airplay stream on your phone directed
| at an Apple TV, the Apple TV doesn't send a switch input
| command.
|
| Oh? My Apple TV 4K (2021) turns on the TV and receiver when
| I start AirPlay, and the receiver switches the input to the
| AppleTV if it wasn't already on it. This works whether the
| TV+receiver were on or off. My TV is a Sharp from ~2013,
| and the receiver is a Yamaha also from around the same
| time.
| tshaddox wrote:
| > - Apple: When you start an Airplay stream on your phone
| directed at an Apple TV, the Apple TV doesn't send a switch
| input command.
|
| I have almost the opposite problem. Any time I turn on my
| TV and receiver to use another device (often my Nintendo
| Switch), the Apple TV somehow wakes up _and then switches
| my receiver 's input to itself_. (My receiver is my HDMI
| switcher and has a single HDMI output to my TV.) This is a
| very annoying problem, and is the only reason I still need
| to have the receiver's remote nearby.
|
| Another unrelated but incredibly annoying problem I have
| with this whole setup is that it's essentially impossible
| to play music through my receiver with my AppleTV _without
| the TV being on_. Turning off the TV will, of course, turn
| off the receiver too.
| blauditore wrote:
| I have the same issue with my XBox: It gets turned on by
| the TV (without me wanting this), but fails to turn on or
| off the TV (which would actually be useful).
| reaperducer wrote:
| _Apple: When you start an Airplay stream on your phone
| directed at an Apple TV, the Apple TV doesn 't send a
| switch input command._
|
| I think it depends on the equipment combination, and its
| state.
|
| I'm able to send an Airplay stream to my AppleTV and it
| both turns on my LG television, and switches the input to
| the AppleTV.
|
| However, if the TV is already on, and I send an Airplay
| stream to the TV it will not switch the input. Which I
| think is an OK measure if you have kids or roommates or the
| TV is in a public setting so that someone might hijack your
| viewing as a joke or to be annoying. My memory is that this
| used to be possible with an earlier model AppleTV, or an
| earlier version of iOS.
|
| That said, ever since I attached a $23 no-name Chinese DVR
| to another HDMI input on the same LG TV, the AppleTV no
| longer has the ability to wake or change inputs. Very
| strange.
| mholm wrote:
| At least for my TV, which is some cheap Element Amazon TV
| from 2017, my Apple TV has full CEC. It will change input
| to Apple TV whenever I interact with it, and can turn the
| TV on directly. So it has to be how the TVs implement
| things. I've wiped my TV firmware back to 2017, so it's
| possible newer TVs intentionally break their CEC features
| to encourage you use their own (bad) smart features?
| reaperducer wrote:
| _it 's possible newer TVs intentionally break their CEC
| features to encourage you use their own (bad) smart
| features?_
|
| In my case, the TV is from 2015.
|
| I know because my wife and I just happened to be in an
| electronics store when the Pope was visiting the United
| States in 2015, and it was on all of the televisions.
|
| At the time, we had a 32-inch TV from 2003ish, and when
| my wife saw the Pope on the 65-inch screen in the store,
| she immediately grabbed a salesperson and said, "I want
| to see the Pope like that."
|
| So, in case you've ever wondered if the programming on a
| TV in a store matters, the answer is "sometimes."
| joosters wrote:
| Sony seem to get this right: My PS4 can turn on my TV and
| switch the input source when it wakes up, but is also
| clever enough _not_ to do so if you wake the PS4 via remote
| play (where you are streaming the output to some other
| device)
|
| However, I think that the issue is that CEC support has
| never been 100% reliable and interoperable. My TV is also
| made by Sony, which likely helps with compatibility.
| Probably all these devices work well with some TVs and not
| others, despite everything claiming to support CEC.
| nsxwolf wrote:
| My PS5 will randomly steal the input from my LG TV's
| internal smart apps. My Nintendo Switch does whatever it
| feels like doing at random.
|
| Frankly I find the technology to be a total mess, and
| there's no way to debug it.
| ziml77 wrote:
| I hadn't noticed that with my Xbox, but then again I may
| actually have the sleep timeout turned off...
|
| I'm surprised that they'd get it wrong though given that
| they've properly supported the HDMI VRR and ALLM features
| since the Xbox One X. (AFAIK Sony doesn't have either of
| those, even on the PS5. And with Nintendo it's surprising
| they have any CEC support at all)
| kzrdude wrote:
| I even programmed my own overlay (app selector) for rpi that
| listens to CEC commands, so I can use the remote's arrows.
| Convenient so that I don't need to reach for
| mouse/keyboard/ssh/phone to start something on the rpi.
| dghughes wrote:
| The slot machine company IGT (now Atronic?) on the AVP platform
| slots had buttons that were two colour small OLED screens using
| HDMI as a connector.
| alana314 wrote:
| Oh cool, I already follow mitxela for his crazy MIDI
| contraptions.
| killjoywashere wrote:
| I feel like cable companies that have found a market with
| overpriced cabling for high-end entertainment systems, like
| Monster and Denon, could make a killing on this.
| trafnar wrote:
| The author should move the fun video at the end to the top!
| xwdv wrote:
| What is this, a display for ants
| eternityforest wrote:
| HDMI is a pretty crazy protocol. CEC, HDMI, and then on top of
| that a dedicated hot plug detect? Is all this really needed?
| Can't I2C do everything?
|
| They could use a 1M pull down on SDA, and pull it up at the
| display side instead of the host side, and have that be hot plug
| detect, and then just use i2c for control as well.
| mikestew wrote:
| Uh, oh. The work project I'm working on uses an OLED display that
| uses an I2C interface. And I happen to have a spare one sitting
| on my desk. And I'm no electrical engineer, so let's see how fast
| I smoke this thing. :-)
|
| Should I succeed, TFA author will not have the worst HDMI display
| ever, as the one we're using is a two-line display looking
| something like this (it _can_ do rudimentary graphics, though; we
| display a company logo at boot):
|
| https://www.mouser.com/ProductDetail/Vishay-Dale/O020O002ALP...
| exikyut wrote:
| OT: I'm idly curious why that display (photo: https://www.mouse
| r.com/images/vishay/hd/O020N002ALPP5N000A_t...) has what
| appears to be a detached single vertical column of presumably-
| unusable pixels on each side of the active area. Obviously to
| do with manufacturing, but... ???
|
| (I'm also curious about the "Pricing: Request a quote" bit.
| Doesn't seem to be "not for new designs", but does have a bit
| about "Factory special order", so perhaps this is just an
| indication of unusually limited supply or something.)
| sircastor wrote:
| Here's my reckless guess: These matrices are manufactured in
| a continuous strip and cropped at the appropriate length,
| then the interface is attached to the cells and it's sealed
| in its case. It would allow the factory to produce varying
| sizes of display.
| dylan604 wrote:
| Why not a simple LCD for this? What benefits from OLED attracts
| your interest?
| newaccount74 wrote:
| If you put an OLED display behind dark plexiglass it looks
| really nice -- the border of the display becomes invisible
| and you see just the letters (or whatever else you are
| displaying).
|
| With LCD there's always backlight leaking.
| toast0 wrote:
| Not the OP, but small OLED displays are pretty low cost, and
| they don't need backlight management because the display is
| emissive. Viewing angles are usually nicer too.
| achairapart wrote:
| I can imagine to look less DIY or "from the 90s". Vanitas.
| nicoburns wrote:
| At those tiny sizes (and in small quantities), the price
| difference is minimal but commonly available OLEDs and and
| LCDs often come in different sizes. So the choice may have
| been more about dimensions than display type.
| mikestew wrote:
| I'm not part of the team that makes such decisions, being a
| lowly software engineer that never got any good at EE.
| However, as one who was at least in the room when such
| decisions were discussed, I believe the decision-making
| process consisted of "OLED would be way cooler, and they're
| not that expensive these days". I'm pretty sure that is the
| sum total of that "engineering" decision. :-)
|
| But I will say that the OLED looks a lot better than most
| LCDs of that type that I've seen.
|
| EDIT: oh, yeah; sibling comment says something about
| backlighting an LCD, which might have had something to do
| with it, as the OLED replaces a seven-segment LED display
| from the previous generation (which, duh, also doesn't need a
| backlight).
| foldr wrote:
| Monochrome OLEDs are very cheap now.
| https://www.buydisplay.com/oled-display/oled-display-panel
| lisper wrote:
| This design is devilishly clever, but a tad misleading. It's not
| really an HDMI display notwithstanding that it is a display that
| plugs into an HDMI port. HDMI has an embedded i2c bus, and this
| project uses that to send images to the display. That's why you
| need a layer of software (xrandr) to translate images that the
| system produces into i2c.
| DannyBee wrote:
| "I have a proclivity to stupid and/or pointless projects. "
|
| <scrolls through rest of project list>
|
| This is hilariously accurate, yet still somehow great.
| v-yadli wrote:
| SSD1306 can definitely do better than 6-10fps, which is close to
| the "software mode" driven by GPIOs, not an actual I2C interface.
|
| Either the DDC is running at very low speed, or... the I2C in
| HDMI in this laptop is actually a software thing?
| 58x14 wrote:
| I love this. What is it about pointless technical projects that
| are sometimes so alluring? I wonder if it's the removal of
| secondhand stress since there is no 'meaningful' success
| criteria.
| ncmncm wrote:
| Anything that involves fooling with physical wires is
| fundamentally more satisfying than anything that doesn't.
| dylan604 wrote:
| Kindred spirit! The one caveat to this rule for me requires
| that as long as there is wood and tools, it is okay to not
| have wires.
| _moof wrote:
| <looks up from hand-riveting a wooden boat and grunts
| approvingly>
| JKCalhoun wrote:
| LED-turn-on > pixel-change-color
| gorjusborg wrote:
| > no 'meaningful' success criteria
|
| Other than personal enjoyment.
| micromacrofoot wrote:
| In the context of observing animals, often vague behavior that
| expends energy for no apparent reason is called "play." This
| fits the bill!
| munificent wrote:
| _> I wonder if it 's the removal of secondhand stress_
|
| Yup, a key component of the sensation of "play" is low stakes.
| drewlander wrote:
| Same here, I thought this was great. Even though I have been in
| the "computer field" for a loong time, there is still so much
| to learn! I love articles like this.
| exikyut wrote:
| Yes, I think removing the "must do a thing" component confounds
| macro-scale sensible classification and measurement of the
| discrete work that is being done. It's possible for manglement
| to see that effort is being invested, but the significance of
| the result cannot be perceived due to lack of resonance with
| the engineering mindset. This makes it possible to personally
| take ownership of engineering agency and may be the core reason
| engineers survive at all because they are able to take and own
| personal responsibility for their own learning.
|
| Knowing it is not possible for others who don't "get" what
| we're doing to usefully measure or judge our work in turn
| disengages the "do thing in anger" stress associated with
| captive/acute focus, and (in ideal, spherical-cow-like
| situations providing infinite time) enables unbounded, open-
| ended introspection into reinforcing the mental solution-
| finding capacity within the domain in question. (In practice,
| infinite time would quite harmful as it would provide more
| space than our attention spans could fill; the practical ideal
| may be to find the right balance between work (acute focus) and
| zoning out, which might be trackable by identifying the precise
| points our ego lags _slightly_ behind, but is cognizant of, our
| as-yet unused physical capacity.)
|
| Being able to engage in this introspection is critical
| important for learning: it's almost like dreaming, in absence
| of any singular focus on finding an optimal solution to a given
| problem within a limited time frame. This makes it possible to
| pay attention to the problem-solving network as a whole, cross-
| reference and merge fragmented ideas that have developed
| independently, and drift toward blurrier edges of understanding
| to help reinforce them (ever noticed how the things you
| instinctively find _super_ interesting that you _really_ want
| to dive into - and often the itches you want to scratch - all
| depend on skills that happen to be _right_ at the point of
| establishing minimum-viable cohesion and fundamentally clicking
| into place? We wander aimlessly... but we don 't!).
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