# AutoBrightness

Simple solution to measure ambient room lighting conditions with an AtTiny85 based USB lux sensor and set external display backlight intensity accordingly via DDC/CI.

See [this blog post for details](https://www.xythobuz.de/auto_brightness.html).

## Sensor

Uses a [Digispark Rev. 3 clone](https://www.az-delivery.de/en/products/digispark-board) with a [GY-302 BH1750 breakout board](https://www.az-delivery.de/en/products/gy-302-bh1750-lichtsensor-lichtstaerke-modul-fuer-arduino-und-raspberry-pi) connected to the I2C bus.

[![Front of PCB](https://www.xythobuz.de/img/autobrightness_pcb_1_small.jpg)](https://www.xythobuz.de/img/autobrightness_pcb_1.jpg)
[![Back of PCB](https://www.xythobuz.de/img/autobrightness_pcb_2_small.jpg)](https://www.xythobuz.de/img/autobrightness_pcb_2.jpg)

### Quick Start

Check out the repo and required submodules.

    git clone https://git.xythobuz.de/thomas/AutoBrightness.git
    cd AutoBrightness
    git submodule update --init

Build the firmware and upload it.

    make -C sensor upload

Prepare udev rules for our new device.

    sudo cp sensor/49-autobrightness.rules /etc/udev/rules.d/49-autobrightness.rules
    sudo udevadm control --reload-rules
    sudo udevadm trigger

## Client

Uses [KWin scripting](https://develop.kde.org/docs/plasma/kwin/) to get the active window from the KDE window manager.
This is used to pause adjustments while a fullscreen window is focused (eg. while gaming).
Also sends status updates to a local InfluxDB.

Run the command-line version with systemd automatically (modify paths in the commands and file accordingly):

    mkdir -p ~/.config/systemd/user
    ln -s /home/thomas/Projekte/AutoBrightness/client/autobrightness.service ~/.config/systemd/user
    systemctl --user daemon-reload
    systemctl --user enable --now autobrightness

Or alternatively modify the paths in the `AutoBrightness.desktop` file and copy it to `~/.local/share/applications` for a graphical version that you can easily auto-start on boot in eg. the KDE settings menu.

### Quick Start

Install dependencies and run the systray client:

    yay -S python-pyusb python-pystray python-pillow python-cairosvg
    ./client/tray.py

Or for just the command-line version:

    yay -S python-pyusb
    ./client/brightness.py

## License

The firmware of this project is licensed as GPLv3.
A copy of the license can be found in `COPYING`.

It uses [V-USB](https://github.com/obdev/v-usb) and is based on their example code.

Also includes the I2C Master implementation from the Atmel AVR310 AppNote.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    See <http://www.gnu.org/licenses/>.