# Exploring PX4 Firmware

This is an advanced (and yet to be completed) tutorial on exploring and modifying the PX4 firmware. The PX4 firmware is the low-level, real-time flight control code that runs on the drone’s flight control board. For this class, the flight control board is the Intel AeroFC but PX4 runs just the same on a wide range of other autopilot boards.

The PX4 source code is all open source and under active development; see here. This means that you can go in an modify the low-level control algorithms that are responsible for keeping your drone in stable, controlled flight! This low-level access is a powerful tool for developing advanced capabilities for your drone, but also increases the complexity and potential safety hazard of operations; thus why this is considered an advanced topic.

In this tutorial we will see how to:

1. Build and flash new versions of Firmware

2. Enable the uORB Listener functionality for low-level debugging

3. Write a Hello World app for PX4