HDMI connection analyzing - Page 1
Forum section: electronics / beginners

author: BoKKeR
author_rank: Contributor
timestamp: August 04, 2017, 08:05:29 am
content: I as many others have bought a Sony TV just to find out that they are notoriously bad when it comes to HDMI. There is a handshake problem with the TV and many of their models.The problem comes up when the TV is power-cycled. The HDMI devices won't show up. I have to manually disconnect them and reconnect them, sometimes multiple times to get them back on.This problem was reported hundreds of times on the Sony support forum with no solution. I am looking for a way to debug this or intersect the connection with a debugger to see where exactly the problem occurs.What would be the best approach? What kind of hardware debugger should I get? Or can a simple RPI or a similar Linux box get to the components low level?I have googled around and found a few HDMI testers on the official HDMI website . One of them is this onehttp://www.quantumdata.com/780d.html?gclid=CjwKEAjwtpDMBRC4xebfxpzu8mUSJAA4c-Tud8M_DCc3MueaJu2tUBFTt773FGonVKjHowYZ-ETVQhoCWbnw_wcB. These ones are obviously out of my price limit but I have seen some for 200$. This would be for analyzing but the next step would be correcting the error that occurs in the connection . I would need to intersect the connection and step in placing a device between the 2 devices. There are a few devices that do this already one of them being this devicehttps://www.google.se/url?sa=t&source=web&rct=j&url=http://www.drhdmi.eu/&ved=0ahUKEwi_hYvPjr3VAhUNElAKHRg1DvoQFgg8MAA&usg=AFQjCNFCP-01YaL0UFYC5vfpsPjgWFh_1Q. I wonder what kind of IC-s can be used for this purpose for experimenting . If it's something off the shelf or something custom made. Thanks for your patience

author: Rerouter
author_rank: Super Contributor
timestamp: August 04, 2017, 08:21:22 am
content: the CDC link which does the intialising is a low speed I2C from memory. should be able to log with a saleae clone.

author: hamster_nz
author_rank: Super Contributor
timestamp: August 04, 2017, 08:37:05 am
content: Some HDMI splitters output unencrypted streams. I am not sure if they Man-in-the-middle the encrypted stream to generate a raw feed or if the HDCP stops at the splitter. One of these might solve the issue completely for near-zero effort.Ic it still misbehaves at the least it would give you something inexpensive that you could crack open and tapto sniff the I2C traffic.

author: BoKKeR
author_rank: Contributor
timestamp: August 04, 2017, 08:52:51 am
content: I have read that the cheap HDMI splitters strip the HDCP requests essentially solving the connection problemMy device does not use any HDCP dmca content but I still think it can be one of the causes for my problem. I will order both a cheap splitter and a logic analyzer. Thank you for all the help

author: andtfoot
author_rank: Unknown
timestamp: August 04, 2017, 08:54:46 am
content: Almost sounds like the hot plug detect signal coming from the screen is inconsistent. Without that, the source won't know what video/audio formats to output, as it usually relies on the hot plug detect to trigger the EDID read.The EDID read itself is over the DDC line, which as mentioned is I2C.The HDMI specs might help here:https://www.microprocessor.org/HDMISpecification13a.pdfFrom what I've seen the cheaper testers seem to only output and receive video, and maybe give an idea of the format. The QuantumData stuff allows you to see a timeline of events, such as the hot plug detect, EDID transfer, HDCP synch, etc.

author: andtfoot
author_rank: Unknown
timestamp: August 04, 2017, 08:57:42 am
content: Quote from: BoKKeR on August 04, 2017, 08:52:51 amWhat sources do you have?It doesn't sound like HDCP, but it's always possible; HDMI can be pretty random sometimes. Sometimes sources will try to use HDCP if it thinks the screen can handle it, even if the content doesn't require it (Mac laptops are a classic example).

author: Zbig
author_rank: Frequent Contributor
timestamp: August 04, 2017, 08:59:15 am
content: Oopsie daisy...

author: BoKKeR
author_rank: Contributor
timestamp: August 04, 2017, 09:19:28 am
content: This might shed some more light to this problem. The source device is a Intel nuc and running 4k 60fps, thus using the HDMI 2.0 protocol. If the problem occurs and I get no signal I can still see under connections that the HDMI is connected but there is no signal. If there is signal the tv stops audio for 2 seconds when I play some video and it displays the source info for a second in the top corner just as when I change the source manually.

author: andtfoot
author_rank: Unknown
timestamp: August 09, 2017, 09:34:32 pm
content: Quote from: BoKKeR on August 04, 2017, 09:19:28 amI've had some issues with PCs not picking up the HDMI properly when connected to TVs. Usually it's the audio not working though, and usually it happens when the PC is switched on while the TV is off. A reset of the HDMI (e.g. using HdmiYo) or a unplug/plug back in routine then gets it going again.It might be worth trying a different source if you have one, preferably something that is designed to connect to TVs (e.g. Playstation, bluray player). It doesn't rule out the TV if it works but might give more clues.

author: BoKKeR
author_rank: Contributor
timestamp: August 11, 2017, 09:34:21 pm
content: I found this on a random sony HDMI thread not related to my Tv but it does sound interesting.2. In the cases of the Samsung Televison (F8000 series) , when the TV reports no signal from receiver overall including GUI/OSD on all inputs. During testing we have found that this occurs more often when the television is started cold, or has been left off overnight indicating a possible hardware related issue on these televisions where latency is too high when started cold. Once the handshake fails, the television locks out all sources (HDCP Shutdown) according to the (EDID) and can only be recovered after power cycling, reconnecting cables, etc. Bypassing the receiver and connecting a source directly to the TV will work since the receiver is locked out by EDID. HDMI reset should resolve (steps are below) as it will clear the HDMI registers in the TV. We are currently investigating further, and will update the related threads with any new information as it becomes available.I am still waiting for my analyserNot to mention that sony posted this as a solution and it stated that after every night you have to reconnect the hdmi cables and wait 5 minutes for the TV to warm up.... I will be doing more tests soon but I am pretty sure this is the problem. I can turn off the TV for a minute or two and the hdmi stays. If I let it cool for 1h the hdmi goes away.