Raspberry Pi 4 and 400 screen blanking

Hi,
I’m having an issue where my RPi 4 (and less often my RPi 400) will blank the screen as I’m using it, or if I just leave it alone. It happens on the RPi 400, but seems far more frequent on the RPi 4, just now I was using it only 5 minutes or so and it blanked.

It’s on RISC OS 5.28, and I’ve got the “disable_gamma” in my config/txt file. It’s running on a Lenovo QHD screen at 60Hz. The display looks great until it blanks.

My case doesn’t have a fan, and it’s got some of those conductive pads to the metal case, the case can feel just a little warm, never hot.

The RPi 400 did this maybe once or twice in a couple of weeks. The RPi 4 has done it several times just today.

I understand this isn’t supposed to happen on stable builds, so anybody have any ideas?

Cheers

Garry

An update, I downloaded CPUClock, and it blanked as I was using it with CPUClock showing temperature of 35 degrees C, so I don’t think it’s an overheating thing.

Does it blank and come back, or blank and stay that way?

Are you playing sound over HDMI and does the blanking correspond to any sound output (such as an error box beep)?

Have you set the config_hdmi_boost at all?

Blank and stay that way, as far as I can tell.

I’m not playing sound over anything, I don’t have any headphones plugged in but I can see the RPi is recognising the HDMI audio, and I quickly tried it now and it beeps through HDMI.

I’ve not set config_hdmi_boost.

Interestingly, since posting, I’ve left the RPi 400 on, and no blanking, whereas I was getting them after 5 mins on the RPi 4.

If screen blanking is the same as screen blacking, then yes. My 4té occasionally blackens, but I always assumed that a flaky HDMI contact was to blame for that. A bit of shaking usually brings the screen back. On the other hand, my 4té2 (which is a Pi4 too of course), hasn’t had any screen blanking so far.

By the way, how do you manage to keep your CPU at 35°C? Mine is twice that, usually.

It’s on RISC OS 5.28, and I’ve got the “disable_gamma” in my config/txt file.

This may be a typo but just in case disable_gamma goes in cmdline.txt

As always with odd Pi issues it is worth querying the power supply.

By the way, how do you manage to keep your CPU at 35°C? Mine is twice that, usually.

If you don’t actually need it running at 2Gz (and who does?), then slow it down. You probably won’t even miss the extra speed.

You don’t drive your car at full throttle.
You don’t have the heating turned up to max.
You don’t boil an egg with the hob full on.

An active fan is also well worth the money.

42.1’C (max over last 72 hours: 51’C

If you don’t actually need it running at 2Gz (and who does?), then slow it down.

Unless something really weird is happening, any Pi since the Pi2 shouldn’t be running full tilt unless it’s actively being used or running something single-tasking. Otherwise, the Wimp ought to be stepping it back to idle speed after a couple of moments.

You probably won’t even miss the extra speed.

Quite so. I’ve slowed my device to idle at 400MHz (instead of, IIRC, 600MHz). When I do something (move the mouse, click an icon…) it briefly jumps up to full speed. I’ve not noticed any degradation.
Hell, unless I’m actually doing something computationally intensive, I’d probably not even notice if it didn’t jump to regular speed. Just try to imagine how many millions of instructions the processor is capable of executing in between the keyboard being poked by those flat fleshy appendages.

You don’t drive your car at full throttle.

You wouldn’t steal a car ¹.

You don’t have the heating turned up to max.

You wouldn’t steal a handbag ¹.

You don’t boil an egg with the hob full on.

You wouldn’t steal a television ¹.

An active fan is also well worth the money.

Yes. I think a fan is a good idea for any ARM once it has passed the GHz barrier. Better to stay cool than risk having pain in the future.

42.1’C (max over last 72 hours: 51’C

That’s about what my Pi3 runs at. There are two fans. A dinky little one in the case (that I’m not so sure is really doing anything much) and a bigger one ² shifting air over the Vonets/power brick/Pi.

I’ve set it to hard-throttle at 55°C. Not sure I’ve reached that yet. ;-) And, yes, I know it’s good to 85°C. Just like a Clio engine can run at 6000rpm ³, doesn’t mean you should.

¹ The fatal flaw in the logic there is that the examples provided are actual tangible things. Stealing a car deprives the owner of their vehicle. It isn’t exactly possible to steal a movie unless you swipe the DVD. By making copies, you are duplicating it. Which, fair enough, may deprive the studio of revenue generated from sales, but that’s not what they are saying here.
I would rather imagine that quite a few people would “steal” a car if there was a fairly simple way to make an exact duplicate of said car, without altering or taking the original.

² One of those twin-fans-with-legs gizmos that you’re supposed to put under a laptop to aid the inefficient cooling inherent in trying to pack a powerful system into the smallest space possible.

³ IIRC, the red line is at 6,500rpm. After that point, you should only run the engine up there if you are fleeing from tanks, zombies, or the Home Office.

Also try a different HDMI cable. I used to have intermittent problems with the first one that came to hand (ca. £2), then I tried it as the DVR/TV interconnect – also flaky, so cut in twain and binned. Current one (ca. £4) is absolutely fine with ARMX6.

Pi3 is running headless ATM, humming along fanless at 43°C, but it is generally lightly loaded.

By the way, how do you manage to keep your CPU at 35°C? Mine is twice that, usually.

35℃ is probably idling. Working harder at 70℃ should not be a problem but it does indicate less than optimal cooling. (If the Pi is at 70℃ when idling at 600MHz then something is not quite right somewhere.) My RPi4, at 2147MHz in a passively cooled flirc case, is topping out at 52℃. On the other hand the Titanium got up to 87℃ yesterday which is just something else not to worry about.

You’re probably being affected by this issue, where PixelValve shuts down on the Pi triggered when the Mouse pointer is being updated.

Somewhere in that thread are links to the underlying issue we reported to the Pi devs.

The fatal flaw in the logic there is that the examples provided are actual tangible things. Stealing a car deprives the owner of their vehicle. It isn’t exactly possible to steal a movie unless you swipe the DVD. By making copies, you are duplicating it. Which, fair enough, may deprive the studio of revenue generated from sales, but that’s not what they are saying here.

The really funny thing about that anti-piracy ad is that the background music was pirated.

Seems my RPi 400 isn’t blanking, at least not any more, I had it on for a few hours today and no problem at all. Yesterday the RPi4 could blank within 5 minutes. I think right now the answer is to just stick with the Rpi 400 and use the RPi4 for Linux instead.

The RPi 400 is also blanking, twice tonight inside 20 minutes, so it’s both my Rpi 400 and Rpi 4 doing this, both brand new.

It seems to happen if I’m in the middle of using it or if it’s just sitting there not doing anything.

Does anybody have any ideas about what might be causing this?

They’re both using a 2560×1440 QHD screen @60Hz with an MDF I made for it, also very new. Could this happen if I made a mistake in the MDF? I mean, the screen looks fine, but is it possible the timing is off or something?

Cheers

Garry

Could this happen if I made a mistake in the MDF? I mean, the screen looks fine, but is it possible the timing is off or something?

This could be the monitor blanking, while the pi is still sending data. Here I have a monitor running off a Windows laptop. Occasionally the monitor blanks while the laptop still shows a picture- It’s a loss of sync somehow.

If you have a way to do it, setting up a VNC server on the pi and watching it from something else might determine whether the pi is blanking (the VNC window will also blank) or whrether it’s the monitor (VNC still shows a screen).

That is a very good idea
– VNC from the Pi 4 to the Pi 400 and Vice versa.
– Also try it with VNC set to lower resolution.
Search Phlamethrower for RISC OS VNCserver and Avalanche for RISC OS VNC Client

Other things to try:-
– Try your old monitor or a TV at 1920×1080 (standard HD)
– Change the resolution to 1920×1080, but still using expensive monitor
– Take up Stewart’s suggestion of a different HDMI cable
– Use ShareFS to check if the system is still running

They’re both using a 2560×1440 QHD screen @60Hz with an MDF I made for it, also very new. Could this happen if I made a mistake in the MDF? I mean, the screen looks fine, but is it possible the timing is off or something?

This is what I have on my RPi400 and AOC 2560X1440 monitor.

In config.txt

# start 2560 x 1440
hdmi_cvt=2560 1440 60 5
hdmi_group=2
hdmi_mode=87
hdmi_ignore_edid 0xa5000080
max_framebuffer_width=2560
max_framebuffer_height=1440
hdmi_pixel_freq_limit=400000000
#end

and its matching MDF entry

# Mode: 2560 x 1440 @ 60Hz
startmode
 mode_name:2560 x 1440 60Hz
 x_res:2560
 y_res:1440
 pixel_rate:241500
 h_timings:32,80,0,2560,0,48
 v_timings:5,33,0,1440,0,3
 sync_pol:0
endmode

It’s the faeries. My Mac & RPi4 are powered through a UPS, the Mac battery backed whilst the Pi is on a straight through socket via a switched adapter. So independently powered? If the Mac is switched on when the Pi is already running, the Pi display blanks momentarily. Nothing seems effected other than the display.

Burst of RF messing with the HDMI?
Start-up surge messing with the monitor?

Burst of RF messing with the HDMI

Yeh, just wondered if it might be similar to Garry’s problem. Not an issue for me.

My AOC 2560×1440 monitor setup is:-

config.txt

hdmi_group=2
hdmi_mode=87
hdmi_cvt=2560 1440 60 3 0 0 1
max_framebuffer_width=2560
max_framebuffer_height=1440
hdmi_pixel_freq_limit=250000000

MDF

# 2560 x 1440 (60Hz)
startmode
mode_name:2560 x 1440 (16:9)
x_res:2560
y_res:1440
pixel_rate:241500
h_timings:32,80,0,2560,0,48
v_timings:5,33,0,1440,0,3
sync_pol:1
endmode

Thanks everyone for the suggestions, I’ll try them out when I have time at the weekend and have some time to leave the machine on for a while.

@Druck, I’ve used your MDF and config.txt, started up fine, so I’ve taken the advice to run VNC on the RPi too so if it does still blank, then I can see if it’s purely the screen or if RISC OS has crashed. Thanks for the help, I’ll update when I get some news.

This may or may not work (given sound is HDMI), but something I find useful is to press F12 and then hit ^G to see if there’s a beep, or not.

I think using David Ruck’s MDF has solved the problem, I have been using the machine for several hours at a time, no problems at all so far. Thanks to everybody for the help.

HDMI sound even works, which I kind of wasn’t expecting.