LCD backlight.

[arjepsen]

Hey.
I'm working on getting the controller of my beer machine set up.
It's an A13-SOM that is connected to some proprietary board, which has an LCD with a capacitive touch panel attached.
I'm using the latest Focal image I found on images.olimex.com.

The panel does work. However, the backlight isn't on at boot, and I have to manually enable it using these commands:

Code Select Expand

echo 35 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio35/direction
echo 5 > /sys/class/gpio/gpio35/value

So it's turned on by setting pin PB3 high.
I've played around with the panel and backlight parts in /sys/class, but so far I haven't been able to turn it on there.
I could put these commands ind a boot script, but I wonder if there's any way to do the same thing through a dts overlay?

regards
Anders

[LubOlimex]

For sure it is possible to add it in the overlay. You can use these overlays as a basis to create similar for the A13 board:

https://github.com/OLIMEX/olinuxino-overlays/blob/master/sun50i-a64/lcd-olinuxino-7cts.dts

https://github.com/OLIMEX/olinuxino-overlays

We haven't used capacitive touch screens with A13 boards (only resistive). It will require some hardware and software effort to get it working.

[arjepsen]

Thanks for your input.
The panel works - although I did spend a long time on getting the capacitive touch panel working (goodix gt911 chip). That part works now.
As mentioned, the display itself also works, but I would like to turn it on through a dts overlay, instead of having to do the "manual" gpio commands.
I did manage to get it to turn on, by adding a fragment part with

Code Select Expand

enable-gpios = <&pio 1 3 0>;However, the screen just lights up completely white, and stays that way...
So it seems like its turned on, but something isn't working the way it should.
If I do the three commands mentioned, I get the command prompt shown, and the panel works as it should.