Maxx2206
Posts: 5
Joined: Fri Mar 13, 2020 3:50 am

p4+7" display no output after reboot

Sat Mar 14, 2020 11:44 am

hi,

this is driving me nuts...
i used the 7" display with my pi 3b's for a long time without issues.
but when i replaced my 3B's with a bunch of 4B's the display started showing a weird behaviour which i couldnt resolve until now:

the pi COLD boots perfectly fine every time... but no matter what i try, if i reboot the display stays black while the raspi boots.
and yes, it boots.. i can not only see the file access led flashing - if i connect a hdmi cable after such a "black reboot" the console contents are shown on the tv set.
with priority to the lcd enabled in config.txt it also cold boots fine into the 7" display even if there is a hdmi cable plugged in. but as soon as i reboot, the system starts booting into hdmi instead.

by default i boot into console btw. i have tried enabling and/or changing some of the display related boot options in config.txt but neither changed anything.
i also installed the new sc card imager tool and installed a fresh raspbian full desktop to a new sd card and it behaves the same.

so since upgrade to the pi 4b's i am no longer able to reboot my pi/7" display combo. i have to shutdown, switch off and switch back on whenever i do any changes or updates the normally would require just a simple reboot.

any ideas?

bubblebobble
Posts: 3
Joined: Thu Jul 04, 2013 9:43 am

Re: p4+7" display no output after reboot

Mon Mar 30, 2020 3:04 pm

I can confirm I've got the same behaviour. Absolutely no idea why. Driving me crackers.

alphanumeric
Posts: 2614
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: p4+7" display no output after reboot

Sun Apr 26, 2020 11:18 am

Not seeing it here. Pi 4B 4 gig and new Ver 2 screen works OK on a reboot.

Maxx2206
Posts: 5
Joined: Fri Mar 13, 2020 3:50 am

Re: p4+7" display no output after reboot

Thu Jun 11, 2020 9:19 am

Hi,

has no one a clue?
sorry to say but with this odd behaviour i am losing most of my fun with the pi4/display combo.
just to be sure i recently downloaded the latest raspbian build via the new installation tool, created a fresh sdcard and kept all the original settings except for the rotation.
the display works like a charm in all aspects on my previous pi2's and pi3's which i have all replaced by 2g/4g pi4 models by now, all showing this behaviour.

same behaviour...
its very disappointing and discouraging to see no reason for this and thus no solution.

Maxx2206
Posts: 5
Joined: Fri Mar 13, 2020 3:50 am

Re: p4+7" display no output after reboot

Thu Jun 11, 2020 9:21 am

hi,
alphanumeric wrote:
Sun Apr 26, 2020 11:18 am
Not seeing it here. Pi 4B 4 gig and new Ver 2 screen works OK on a reboot.
whats the (technical) difference to the v2... and how do i determine which version i have anyway?

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dliloch
Posts: 172
Joined: Wed Jun 27, 2012 6:28 pm
Location: cleveland, ohio usa

Re: p4+7" display no output after reboot

Sun Jun 28, 2020 12:48 pm

I have the same behavior and I assume I have a V1 screen.. how do you tell the version of the screen? I have to power cycle to get it working again.

alphanumeric
Posts: 2614
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: p4+7" display no output after reboot

Sun Jun 28, 2020 1:07 pm

Have a look at the silk screened text on the driver board. I have a version 1 screen and a version 2 screen. My version 2 screen is in a SmartiPi V2 case that I'm not fussy about taking all apart.
And my Version 1 screen has a cover over the driver board and a Pi 3B+ mounted on top of that. I can't see the driver board. That one would also be a bit of work to get apart for access to the driver board. That Pi also has a ribbon cable attached to the GPIO that's not easy to get at because of the case on the Pi.

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dliloch
Posts: 172
Joined: Wed Jun 27, 2012 6:28 pm
Location: cleveland, ohio usa

Re: p4+7" display no output after reboot

Sun Jun 28, 2020 1:13 pm

Thanks..I see clearly it is a V1..2014. I am wondering if the rpi4s power down the gpio rail on reboot and if the V1 display is sensitive to this? I am going to power the display with 5v external and see if that is the case. It did not matter if the external 5v was applied...maybe the problem is the 5v does not drop on a reboot?

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rpdom
Posts: 17427
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: p4+7" display no output after reboot

Sun Jun 28, 2020 1:30 pm

dliloch wrote:
Sun Jun 28, 2020 1:13 pm
Thanks..I see clearly it is a V1..2014. I am wondering if the rpi4s power down the gpio rail on reboot and if the V1 display is sensitive to this? I am going to power the display with 5v external and see if that is the case. It did not matter if the external 5v was applied...maybe the problem is the 5v does not drop on a reboot?
The 5V rail on the GPIO is connected directly to the USB-C power connector on the Pi 4B, and via some protection circuitry on most other models. It does not controlled by anything on the board. The 3.3V and other rails may be reset on boot by the PMIC chip that generates them.
Unreadable squiggle

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dliloch
Posts: 172
Joined: Wed Jun 27, 2012 6:28 pm
Location: cleveland, ohio usa

Re: p4+7" display no output after reboot

Sun Jun 28, 2020 2:18 pm

Thanks..then maybe a new signal going to/from via the ribbon cable..I wonder if there is a way to turn the display off and on again once it is rebooted..from my ssh session. And I guess the question is becoming is the V1 raspi 7” LCD display fully supported by the rpi V4 series..at this point I would say not. Again it functions fine in all other respects.

alphanumeric
Posts: 2614
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: p4+7" display no output after reboot

Sun Jun 28, 2020 2:44 pm

Both of my screens are being powered via the Micro USB power jack on the driver board. Both the Pi and the screen are feed from the one power supply via a Y power cable.

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dliloch
Posts: 172
Joined: Wed Jun 27, 2012 6:28 pm
Location: cleveland, ohio usa

Re: p4+7" display no output after reboot

Mon Jun 29, 2020 11:43 am

Is there a way or commands to turn on the 7” raspi display if it is off and the machine s running? If so then I can simply put them in the startup commands and I will have my display working on reboot.

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