My Usually Non-sense Ramblings

Raspberry Pi 3 Tablet-like System

20180806-1614

I got myself the latest Raspberry Pi 3 B+, which is a 1.4GHz 64-bit quad-core ARM-based processor with 1 GB SDRAM. Put that together with a 7-inch LCD and a nice enclosure, we get a Linux tablet! Yay!

Anyways, the enclosure settings is unfortunately 180degrees rotated and requires an edit to config.txt - simply add lcd_rotate=2 line to that file.

On a side note, the LCD brightness can be controlled using sysfs interface but it requires root access. To check current brightness,

cat /sys/class/backlight/rpi_backlight/brightness

and to set a value between 0-255 (can check maximum value using max_brightness interface),

echo 64 > /sys/class/backlight/rpi_backlight/brightness

We can also control the backlight, and to turn OFF the backlight,

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

It uses inverted logic (0 to swith ON).

Since this setup uses the display ribbon interface, the HDMI output is still available and you would think, "Yay! Dual monitors?"... nah! At the moment, this is a low-level setup kinda thing and thus not available. Some software (omxplayer?) may dump video output on the secondary framebuffer, but the general rule is only one display at one time and this is only selectable at boot time. To change, run (as root) raspi-config and select Advanced Options then A7 GL Driver. To use LCD, select the one with fake KMS and to use HDMI, select the one with Full KMS (I guess KMS is kernel mode setting?). So, when HDMI is used, LCD display is still powered (although not driven), so to save power, we can switch OFF the backlight (told ya it could be useful).


Another New Beginning...

20180324-2152

I am planning to start writing stuffs here instead of the old http://blog.my1matrix.org (this URL now redirects here), which is actually located at https://my1azman.blogspot.com (hosted by blogger-dot-com). I will remove the my1matrix redirection in the near future, but the blogspot/blogger-dot-com address will always be available (as long as it is free :p).

Note: I just noticed that the blogspot.com domain is now automatically redirected to blogspot.my.