Adding functionality to the I2C bus


Our plane will fly at night sometimes, so we will need to add lighting controls to our controller. Is there a tutorial that takes you through Qgroundcontrol > Mavlink > Pixhawk Orange Cube’s I2C bus? We would look at adding a something like a PCF8574AN I/O expander. I have seen code snippets, but am just wondering if there is something end to end. Thank you!