I think the problem comes from redirecting the output. The ">" operator is a redirect which is done by the shell. You'd need to login as root so you'd have a root shell that would persist through the redirect and have root permission to change the file.Snyder wrote:I got the same error as described by Andrew earlier in this thread: Permission deniedCode: Select all
echo 0 > /sys/class/backlight/rpi_backlight/bl_power echo 1 > /sys/class/backlight/rpi_backlight/bl_power
I also tried to execute the above mentioned code with sudo but it didn´t help.
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sudo bash -c "echo 0 > /sys/class/backlight/rpi_backlight/bl_power"
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[email protected] ~ $ sudo echo 1 > /sys/class/backlight/rpi_backlight/bl_power
-bash: /sys/class/backlight/rpi_backlight/bl_power: Permission denied
[email protected]oomboxII ~ $ sudo bash -c "echo 1 > /sys/class/backlight/rpi_backlight/bl_power"
[email protected] ~ $ sudo bash -c "echo 0 > /sys/class/backlight/rpi_backlight/bl_power"
[email protected] ~ $ sudo bash -c "echo 1 > /sys/class/backlight/rpi_backlight/bl_power"
Write failed: Broken pipe
[Prozess beendet]
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sudo bash -c
Please Gordon, could you confirm that brightness control wouldn't be possible. I bought it thinking that it will and without it is absolutely unless.gsh wrote:That's the easy bit...
echo 80 > /sys/class/backlight/rpi-backlight/brightness
With my current build (not released yet) will do that... The thing I'm having trouble with right now is getting it to correctly blank the backlight when it goes to suspend, sometimes it works sometimes not...
Gordon
I tried running a bash string and also running a python script. Both possibilities work fine for me. But sometimes my pi2 crashes.Or run a bash string command with sudo such as
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sudo bash -c "echo 0 > /sys/class/backlight/rpi_backlight/bl_power"
Or put it in a script (Python or Shell) and run that using sudo.
It's a binary control (on or off) not brightness.ulix wrote:Could anyone form the foundation clarify the brightness control?
Thanks!
The Foundation have learned not to pre-announce software or hardware (after making a dreadful foul up with the official screen announcement almost two years before it was available). Assuming it's even technically possible with the official screen hardware you won't be told until it's available. You can be fairly sure it's on the wish list (because they're not ignoring the forum).ulix wrote:Yes, I got this... but will brightness controll be available?
If the foundation makes more infos available we could think about it..
cheers
Well, actually they have told us it is not possible.DougieLawson wrote: The Foundation have learned not to pre-announce software or hardware (after making a dreadful foul up with the official screen announcement almost two years before it was available). Assuming it's even technically possible with the official screen hardware you won't be told until it's available. You can be fairly sure it's on the wish list (because they're not ignoring the forum).
Now we would like very much to know why not? Because maybe there is some (unofficial hack etc. e.g. losing CE certification is no issue to us, as we have to certificate our product anyway...) way to get it working. This would be very important information for (what it seems) many of us here, as at the moment the screen is unusable in several applications because of the unchangeable brightness. It would be important to know, also because if there is absolutely no work around we could shift our efforts else where and stop wasting our time (=money!) with this display. It is very sad and strange that we are not getting any response from the foundation, even that several people are asking politely. It is getting quite rude and disrespectful how they are handling this issue. Silence is newer a good way to treat customers...jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
Christian, it was a problem with the power source.cpfeil wrote:
Maybe a problem with your power source?
I have no ideaMarques de Monsas wrote:DougieLawson wrote:
Well, actually they have told us it is not possible.Now we would like very much to know why not? ...jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
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sudo bash -c "echo 0 > /sys/class/backlight/rpi_backlight/bl_power"
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sudo bash -c "echo 0 > /sys/class/backlight/rpi_backlight/bl_power"
sudo bash -c "echo 1 > /sys/class/backlight/rpi_backlight/bl_power"
This is no display sleep mode, it is the kernel screensaver. You can disable it likeswitchcodes2 wrote: - Is there any way to completely turn of Sleep mode, and force screen never to sleep?
This is a thread I posted on adding a button to toggle the display backlight on and off.backmailingbox wrote:Hi, I need to switch off and switch on the backlight from pyton
I recieve only err 13 - permissions......
How to solve this problem?
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[SeatDefaults]
xserver-command=X -s 0 -dpms
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echo > file
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sudo echo > file
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sudo sh -c "echo > file"
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"echo > file"
Mine has "Raspberry PI Display V1.0" printed right under the Raspberry Pi logo. I assume the new ones would have "V1.1".W. H. Heydt wrote:Is it possible that the way to tell V1.0 from V1.1 is whether the controller board is already connected to the panel or not when you get it? (If so, I have a V1.0 unit, and converting it to V1.1 would be desirable, but I'd be happy to buy a V1.1 unit if that's what it takes to get one with truly adjustable brightness.)