OpenMarine
How do I adjust screen luminosity - Printable Version

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How do I adjust screen luminosity - Didier B - 12-06-2017

Hi
I just received a new screen by Waveshare (10.1inch, IPS, 1280x800 HDMI, capacitive touch control). It worked 'out of the box'.
It avoids the drawback of the "too small" 7 inch which was limited to 800x480, and did not allowed to reach the OK button in many windows ...
It can hold on his back the RPi cards plus HATS (holes pre-drilled, and screws and spacers in the package).
Off course its packaging implies an installation down below, at the navigator station.
The intensity under 5.2V is below 0.9 Ampere, consumption 4.7 W ! (My older 'office type' screen needed 2.7 A x 12.4 V = 34 W, - 7 x higher !)
No OSD, nor luminosity H/W control...

Now my questions : Is there a software way to control the display luminosity ? 
In Navigatrix an utility called Redshift is available, which does the job. Is it, or could it become, applicable to OpenPlotter?
Or is there any known alternative ? (even a manual solution would help )


RE: How do I adjust screen luminosity - jim321 - 12-06-2017

for  open cpn push "c" or "view" and change color scheme .
or on the display its self "manual solution"


RE: How do I adjust screen luminosity - Littlechay - 12-09-2017

(12-06-2017, 07:17 AM)jim321 Wrote: for  open cpn push "c" or "view" and change color scheme .
or on the display its self  "manual solution"

F5, F6 & CTRL+G in OCPN are the colour scheme and brightness controls. 

https://opencpn.org/wiki/dokuwiki/doku.php?id=opencpn:opencpn_user_manual:toolbar_buttons:night_navigation

Otherwise at system level in the PI

Need to be su for some reason

Code:
sudo su

The driver for the screen provides an interface through /sys/. To turn the screen on you can use the command:

Code:
echo 0 > /sys/class/backlight/rpi_backlight/bl_power

and to turn it off:

Code:
echo 1 > /sys/class/backlight/rpi_backlight/bl_power

the brightness can be adjusted using:

Code:
echo n > /sys/class/backlight/rpi_backlight/brightness

where n is some value between 0 and 255.


RE: How do I adjust screen luminosity - Didier B - 12-13-2017

Hi Chris, 
Well, I knew the F5 key, but it doesn't aapplies to raster charts.
F6 and CTRL+G have no effect in OPenPlotter's Open CPN ...
Regarding the bash commands, in OP 0.16.0, /sys/class/backlight/ is an empty directory....
Searching  with file manager 'rpi_backlight' gives 0 answers.
Too bad it doesn't work as this precisely what I was looking for...a way of dimming screen luminosity Sad


RE: How do I adjust screen luminosity - Littlechay - 12-13-2017

FT works with raster charts that have been built with the correct pallets, try the NZ ones for example.

You'll probably have to modify the command line to match your monitor exactly. All I can say is that is the command that I use. It can be mapped to a couple of buttons to give a pseudo hardware method of adjustment.