Trouble Getting HDMI Output From RPi4

[matthait]

Got a new pi 4 4gb model today.
After etching Buster and initial set up system would not boot with dual monitors connected.
Would boot with only one monitor in hdmi 0 (did not matter which of the two monitors i used, they are the same model number)
After lots of troubleshooting solved dual monitor boot up issue you guys may be having by using the following.

when turning on the Pi 4 (plugging in or from reboot) I have to power cycle one of my monitors (plugged in hdmi port 1) so that the monitor does not time out (no signal displayed on monitor) before the pi displays the 4 pis on the primary screen. If i time it right, i get a rainbow square on the other screen.

I have tried many ways in config.txt to fix this timeout issue but I believe its part the pi problem, part Buster problem, and part my monitor.

if i do not time the power cycle of the monitor right, the unit locks up after the 4 pis and will not display anything on either monitor and will not boot far enough to permit an SSH connection.

Hopefully this helps someone else

[Mortimer]

I am having trouble getting HDMI output from my new RPi4. I am able to get to it via SSH, so would appear to be working. The display (Motorola Atrix Lapdock) is not complaining that there is no signal, which it does if I switch the connection to the HDMI-1 port. So I presume there is a signal there, but the lap dock is not displaying it.

I tried the following:

hdmi_force_hotplug:0 = 1
hdmi_group:0 = 2
hdmi_mode:0 = 39

The lap dock now displays the four raspberries, then it blanks with a flashing cursor. I will get a brief flash of the splash screen (less than a second) a few more seconds of flashing cursor then the screen goes completely black and nothing further is displayed.

Any ideas?

Does the output work when plugged in to a normal HDMI equipped monitor or TV? (I'm presuming the lapdock this is some sort of HDMI->LCD system?)

I will give it a try when I have a chance. To be honest I am not hopeful because in my experience the lap dock has been the least fussy HDMI display in the house, and my "go to" device when I have problems with other devices.

It will have to wait until I get a cable or adapter, because I only have a uHDMI to uHDMI cable at the moment.

[BogoMax]

I'm using a Pi4B with twin BENQ GW2406Z 23" 1080p monitors (and a Pimoroni fan shim which keeps it at around 40 DegC).

The Pi wouldn't reliably boot with both monitors attached although it always booted from HDMI0 with just one monitor.

About on in 10 boots with both monitors attached resulted in a successful boot.

The was a thread in one of the forums which suggested adding "core_freq_min=500" to /boot/config.sys.

This has done the trick for me and now the Pi4 boots with both monitors on every time.

Hope this helps someone.

[lemonahmas]

I met the same problem, my RPi4 can boot and I can ssh into it even use rdp but it does not output anything to the hdmi monitor.

[thatchunkylad198966]

Same kinda problem here, HDMI-0 is fine but HDMI-1 is problematic.

[BoydLabBuck]

Based on this thread https://www.raspberrypi.org/forums/vie ... 8&t=244596 I ran sudo rpi-update, reset the config.txt to initial settings, and it works! YMMV.

[HawaiianPi]

For those having overscan problems on a TV, look in your TV settings for a way to disable overscan on the HDMI input you are using. If your TV is 1080p it should have a setting, but it may not be called overscan, and each TV manufacturer seems to have their own name for it.

Or, check if you have an HDMI input marked for PC (usually with a nearby audio input). That HDMI input may have overscan disabled by default.

[procount]

@Mortimer - It turns out I already had a uHDMI socket -> plug extension cable, so I was finally able to connect my Pi4 up to my lapdock.
I already had the SD card configured to use HDMI and VGA666 on the GPIO pins, so I plugged it in and booted.
i didn't have any problems at all. I had an extended desktop across the VGA666 interface and the HMDI0 connected lapdock.

Well, the only problem I had was my uHDMI cable is a bit flaky and I had to wiggle it occasionally when the picture disappeared.

You do need the USB cable connected between the lapdock and the Pi4 so the lapdock knows something is connected (even though I used an external mouse and keyboard because my lapdock has some dead keys).
I powered the Pi4 from the USB-C output port of my laptop whilst it was running on batteries.

[richcreedy]

I tried doing the updates and upgrades, managed to see the four raspberries on my lapdock, but didn't display the gui (desktop)
connected a vga monitor with the appropriate HDMI-> VGA adaptor that works fine.

it does look like raspian is booting properly, but not outputting the correct hdmi signal for the lapdock, I tried hot-swapping the the screen, and it sort of works with the wrong resolution.

[markewallace]

New Pi4 user here. Pardon the newbiness, please.

I just received my RPi4 from Canakit yesterday. All stock Canakit gear; RPi4, mouse, keyboard, power supply, HDMI cable, case, heat sinks, SD card, etc. All of it from their kit.

Followed all of the instructions and was able to get the default OS installed and up-n-running. No problem at all.

Curious about my RPi and what else I could put on it, I started flipping through menus and looking for stuff to install; however, before I could actually get anything else installed, suddenly my screen (a Sharp 50-something-inch TV) went blank and then I got a "No Signal" from it.

I have tried unplugging/replugging the power and HDMI inputs/outputs as well as trying different HDMI ports on the TV. Nothing seems to bring the video back.

The red light on the end of the RPi is red. I haven't looked to see if this is bad or good.

Any tips for me? I am concerned that it went from seemingly working just fine to suddenly all black and "No Signal" from the TV. I can move my Roku on that same TV to any of the ports where the RPi isn't working, and the Roku will work on any of them. Doesn't *seem* to be a TV problem.

Thank you,

Mark

[Mortimer]

@Mortimer - It turns out I already had a uHDMI socket -> plug extension cable, so I was finally able to connect my Pi4 up to my lapdock.
I already had the SD card configured to use HDMI and VGA666 on the GPIO pins, so I plugged it in and booted.
i didn't have any problems at all. I had an extended desktop across the VGA666 interface and the HMDI0 connected lapdock.

Well, the only problem I had was my uHDMI cable is a bit flaky and I had to wiggle it occasionally when the picture disappeared.

You do need the USB cable connected between the lapdock and the Pi4 so the lapdock knows something is connected (even though I used an external mouse and keyboard because my lapdock has some dead keys).
I powered the Pi4 from the USB-C output port of my laptop whilst it was running on batteries.

Thanks for the pointers, I'll give it another go when I get home (away at sea at the moment).

[penguintutor]

I've found a way to get the HDMI working on a NexDock (v1). It may help with others that are having similar problems with other HDMI devices.

When connected to the NexDock then I just got a blank screen. It appears to be a problem with the Pi (Raspbian) reading the EDID information from the screen. I disabled that and manually chose a suitable resolution and that is now working.

First connect the screen to another computer and work out the resolution setting you want to use.

Then find a suitable matching setting at: https://www.raspberrypi.org/documentati ... t/video.md

Configure config.txt to ignore edid and force the particular mode you want.



These are the entries in my /boot/config.txt for a NexDock.

Code: Select all

hdmi_ignore_edid=0xa5000080

hdmi_group=2
hdmi_mode=86

hdmi_force_mode=1

This provides a resolution of 1366x768

[WorldScott]

Thank you to scotty101!

Your suggestion did the trick to make my new RPI work.

On my 30" Apple Cinema HD monitor I commented out the dtaoverlay line

From

Code: Select all

dtoverlay=vc4-fkms-v3d

To

Code: Select all

#dtoverlay=vc4-fkms-v3d

and that did the trick!

I think my monitor is getting too old for this fancy newer Raspberry Pi 4!

Cheers,

-Scott

[markewallace]

Anyone have any thoughts for me on my post about four or five messages back?

Thank you,

Mark

[HawaiianPi]

New Pi4 user here. Pardon the newbiness, please.

... however, before I could actually get anything else installed, suddenly my screen (a Sharp 50-something-inch TV) went blank and then I got a "No Signal" from it.

I have tried unplugging/replugging the power and HDMI inputs/outputs as well as trying different HDMI ports on the TV. Nothing seems to bring the video back.

Are you using a direct micro-HDMI to HDMI cable, or a micro-HDMI adapter?

The red light on the end of the RPi is red. I haven't looked to see if this is bad or good.

Red LED means you are getting power. Does the green activity LED blink at all, and is it random or a pattern?

Any tips for me?

Read the boot problems sticky for troubleshooting tips.
https://www.raspberrypi.org/forums/view ... 28&t=58151

[markewallace]

Are you using a direct micro-HDMI to HDMI cable, or a micro-HDMI adapter?

Using all stock everything, including the direct micro to HDMI cable from Canakit.

I took the whole setup upstairs last night and plugged it in to my Dell monitor. I still get a No Signal, but I found that it is just from *one* of the HDMI ports. The other one works fine.

Is it possible that plugging the Pi in to my TV fried the HDMI port? It worked briefly a few days ago but then gave me the No Signal thing, and now that same port doesn't work on just a regular monitor.

I haven't tried taking the Pi back downstairs and plugging it back in to the TV. A little nervous that that could fry my only remaining HDMI output, if indeed that is what happened on the first one.

Mark

[thatchunkylad198966]

Are you using a direct micro-HDMI to HDMI cable, or a micro-HDMI adapter?

Using all stock everything, including the direct micro to HDMI cable from Canakit.

I took the whole setup upstairs last night and plugged it in to my Dell monitor. I still get a No Signal, but I found that it is just from *one* of the HDMI ports. The other one works fine.

Is it possible that plugging the Pi in to my TV fried the HDMI port? It worked briefly a few days ago but then gave me the No Signal thing, and now that same port doesn't work on just a regular monitor.

I haven't tried taking the Pi back downstairs and plugging it back in to the TV. A little nervous that that could fry my only remaining HDMI output, if indeed that is what happened on the first one.

Mark

I'm guessing you tried HDMI-0 and that worked but HDMI-1 didn't. that happened to me too and others.
Guess it's a known issue...

[markewallace]

I'm guessing you tried HDMI-0 and that worked but HDMI-1 didn't. that happened to me too and others.
Guess it's a known issue...

But it worked briefly and now doesn't work on either of two displays.

Is there a way for me to tell if the port is just dead now?

If so, I need to get the board exchanged for a good one. Right now I only intend to use one monitor, but it's possible that someday I will want to use two, for which of course I would need two functional HDMI ports.

Mark

[thatchunkylad198966]

I'm guessing you tried HDMI-0 and that worked but HDMI-1 didn't. that happened to me too and others.
Guess it's a known issue...

But it worked briefly and now doesn't work on either of two displays.

Is there a way for me to tell if the port is just dead now?

If so, I need to get the board exchanged for a good one. Right now I only intend to use one monitor, but it's possible that someday I will want to use two, for which of course I would need two functional HDMI ports.

Mark

Yes, same here; you could always try and RMA it from where you purchased from but you're not the only one and afaik it will be fixed via an update.

[rwcooper]

Hi, I am so glad I found this thread. It's wasn't until I commented out dtoverlay that I got my 11.6" Eyoyo monitor to work. I now have the following in the config.txt file:

#enable vc4
#dtoverlay=vc4-fkms-v3d
max_framebuffers=2

hdmi_force_hotplug=1
hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=39

Before commenting out dtoverlay the monitor would display correctly in text mode, but as soon as I started a window manager it would go into 1080p mode, which looked horrible as the native resolution is 1360x768.

[THX1182]

I've been having issues with hdmi as well, basically tried everything I could find, but nothing seems to resolve the issue...

(Swapping cables, config.txt editing, reinstalling, new Power supply)

The Pi loses connection with my TV for two seconds, after playing media of any kind... I think it's hdmi audio related, because it does not happen with analogue audio.

Here's a video of what's happening:

https://imgur.com/gallery/n2bRnWE

These are some of the outputs of tvservice:

1 attached device(s), display ID's are :
Display Number 2, type HDMI 0

HDMI events what happens after media is played:

Starting to monitor for HDMI events

HDMI cable is unplugged. Display 2
HDMI is attached
HDMI cable is unplugged. Display 2
HDMI is attached

state 0xa [HDMI CUSTOM RGB lim 16:9], 1920x1080 @ 60.00Hz, progressive

Audio information:

PCM supported: Max channels: 2, Max samplerate: 48kHz, Max samplesize 16 bits.
AC3 supported: Max channels: 6, Max samplerate: 48kHz, Max rate 640 kb/s.
DTS supported: Max channels: 2, Max samplerate: 48kHz, Max rate 640 kb/s.


Not to hijack this thread but since the raspi team is looking into "hdmi problems", i decided to link my thread here before my thread dies.

Here's a link to my original thread:

https://www.raspberrypi.org/forums/view ... 5#p1558785

Hope that my issue falls under the "hdmi issues", that the developers are looking at, because this has been driving me crazy for weeks now.

[THX1182]

Can the raspberry pi team please STICKY this thread? Seeing as the team are working on resolving hdmi issues at the moment???

[jamesh]

Can the raspberry pi team please STICKY this thread? Seeing as the team are working on resolving hdmi issues at the moment???

We don't stick threads like this, and that won't help from an engineering point of view anyway. To really get it 'stuck' so its gets worked on you need to add an issue to our github repo.

[THX1182]

Can the raspberry pi team please STICKY this thread? Seeing as the team are working on resolving hdmi issues at the moment???

We don't stick threads like this, and that won't help from an engineering point of view anyway. To really get it 'stuck' so its gets worked on you need to add an issue to our github repo.

Thanks for responding to me jamesh...

Will do that asap.

Keep up the great work.

[klricks]

I have had the no display issue with my RPi 4 and a RPi3B+
Sometimes I get no display and sometimes display but wrong resolution(s).
This tends to happen after a power outage.....

To get back to normal I did this:
- Power down the RPi and remove USB power connection
- Power down TV and remove AC mains power plug.
- Wait a minute or so then reconnect the AC mains power to the TV.
- Power up the RPi.
- Leave TV connected to AC mains at all times.