hdmi wake up

General support for the Pi-Star System
ve2se
Posts: 3
Joined: Sun Nov 03, 2019 9:11 pm

hdmi wake up

Post by ve2se »

After a while hdmi port switch disable , How to wake up the hdmi port ? Or disable the time out ?
ve2se
kc7ngc
Posts: 48
Joined: Fri Sep 21, 2018 2:47 am

Re: hdmi wake up

Post by kc7ngc »

Need more detail as power management/blanking etc is different across the OS releases and hardware.

Which Model Raspberry PI are you using?
Which version of pistar are you using?
ve2se
Posts: 3
Joined: Sun Nov 03, 2019 9:11 pm

Re: hdmi wake up

Post by ve2se »

i am using a raspbery pi 3+ and Pi-Star:4.1.0-RC4 / Dashboard: 20191101
tnx for reply
kc7ngc
Posts: 48
Joined: Fri Sep 21, 2018 2:47 am

Re: hdmi wake up

Post by kc7ngc »

Sorry for late reply. IN the ultimate irony, my monitor died over the weekend.

Official documentation from raspbian that documents how to disable screen blanking of text and graphic consoles is here:
https://www.raspberrypi.org/documentati ... ensaver.md
Which should work on the 4.1 beta of pistar.

Be careful when editing the kernel boot command line info as if you type it your card won't boot and you will need to put card into another machine to be able to fix the error. So I recommend backing up the cmdline.txt file someplace before you edit it to make it easier to undo any potential mistakes.

If you are having an issue when monitor is turned off and back on that nothing ever displays again on the monitor you might need to try forcing HDMI detection to allways be on for the raspberry pi.
Do so by editing the /boot/config.txt file on the raspberry pi and try uncommenting the line that says hdmi_force_hotplug=1 by removing the # at the front of the line so the section looks like below. Save the file, then shutdown and reboot the raspberry pi.

Code: Select all

# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1
kc7ngc
Posts: 48
Joined: Fri Sep 21, 2018 2:47 am

Re: hdmi wake up

Post by kc7ngc »

Some additional info. For testing purposes you can toggle HDMI display output on and off using the following commands over SSH:

To power off:

Code: Select all

vcgencmd display_power 0
To Power on:

Code: Select all

vcgencmd display_power 1
ve2se
Posts: 3
Joined: Sun Nov 03, 2019 9:11 pm

Re: hdmi wake up

Post by ve2se »

No luck my tv show hdmi no signal , i have to reboot the pi to have it again to get hdmi signal back on , until time out
m1cfk
Posts: 17
Joined: Sun Apr 12, 2020 7:56 am

Re: hdmi wake up

Post by m1cfk »

I find this too on my pi0w.
tried the above but makes no difference.
no hd signal out after pi being on for a while.
m1cfk
Posts: 17
Joined: Sun Apr 12, 2020 7:56 am

Re: hdmi wake up

Post by m1cfk »

this seems to restart the port, but now just get a black screen and nthing else

To turn off your monitor with tvservice, run:

$ tvservice --off

You can then wake the monitor back up with:

$ tvservice --preferred
m1cfk
Posts: 17
Joined: Sun Apr 12, 2020 7:56 am

Re: hdmi wake up

Post by m1cfk »

yea, got kb in. I unplugged and replugged to get a redetect but makes no change there :(
Does the usb ports go to sleep after no activity? no idea.
n7ekg
Posts: 10
Joined: Tue Nov 02, 2021 3:01 pm

Re: hdmi wake up

Post by n7ekg »

I've also been able to duplicate this behavior in a fresh install of 4.1.5. I've got an application running on the console that refreshes the display every minute or so, and after a while the HDMI display signal shuts off. No amount of keyboard or mouse activity will wake it up. Rebooting the Pi (4B, 8GB of RAM) brings everything back to normal.

As for the pi-star being designed to be headless, I don't see how this would in any way affect the HDMI display code.
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