How do I adjust screen luminosity

[Didier B]

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 )

[jim321]

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

[Littlechay]

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.p...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.

[Didier B]

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

[Littlechay]

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.

[Pompey]

FT works with NooCube and 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.

Hi Littlechay, how difficult is to modify the command line to match the monitor? Is there a guide or a tutorial somewhere?

[Hillzzz]

I have just got a similar screen its a Digiwave HA-101ZIEBCAD1-V 10.1 inch projected capacitive touch 1280x800 HDMI LCD screen. The touch interface is enabled either via USB (which needs a special USB lead) or IC2. The main difference to Didier B's screen is that this one is daylight readable at 1250 nits. Its actually almost too bright to use indoors so I really need to dim this screen. I am still trying to find the solution but there is a 3 pin connector on the LCD Driver circuit board. Pin 0 is ground, pin 2 is PWM Pull up to 3.3volts and pin 3 is not connected. as I understand things thus far it is possible to connect this connector on the screen to two GPIO pins on the Pi the Pin 1 connects to any Ground GPIO pin and pin 2 I think to raspberry pi GPIO 13 physical Pin 33. Then you use software to modulate the apparent voltage on GPIO 13 well thats what I think thus far. So look to see if a similar GPIO connection is required on the Waveshare screen. I will let you know how I get on as this daylight readable screen looks like it will make a great plotter for the helming position if i can sort it out.

[Hillzzz]

Hi all, I am making progress with the Digiwave HA-101ZIEBCAD1-V 10.1 inch projected capacitive touch 1280x800 HDMI LCD screen. I have written a program that has a launch icon in the accessories menu and a main program that draws a slider and sets the value of PWM Pin12 GPIO18 between 17% and 100% 17% being the minimum value that will display a backlight below 17% the screen backlight turns off. It all works sort pf OK which is one heck of a surprise to me as my Python Programming skills are near zero. However I have one problem I can't seem to solve. When I exit the slider the Value of GPIO PWM immediately falls to zero. What I need is for the PWM pin to stay at the last set value until the slider is called again or the Pi is shutdown. does anyone know how to do it? If so I think the app will be useful to the OpenPlotter community as the default brightness only works with the official Pi screen and thats not daylight readable. Thanks all.