5cdf5ac482
On Linux targets with high-rate external sensor data (>1000Hz), all sensor calibrations (gyro, accel, mag) can freeze PX4 by starving other threads of CPU. Normal flight is unaffected — only calibration triggers the problem. Two compounding issues in the calibration worker threads: 1. calibrate_cancel_check() creates a new uORB::Subscription on every call, which triggers getDeviceNodeLocked() — an O(n) linear strcmp scan through all uORB nodes. In gyro/mag calibration this was called on every sensor sample, consuming the majority of CPU in strcmp alone. 2. SubscriptionBlocking::updatedBlocking() returns immediately when data is already available (it only blocks when no data is pending). With continuous high-rate sensor data, the calibration loops never yield, spinning at 100% CPU. These problems are addressed with this patch as follows: - Throttle calibrate_cancel_check() to once per 200ms in gyro and mag calibration loops. - Add 1ms px4_usleep() yield before updatedBlocking()/updateBlocking() in all calibration loops (gyro, accel, mag, orientation detection). This caps the effective loop rate at ~1000Hz — still far above what calibration needs (250-750 samples). - Force Commander main loop to sleep during calibration so it does not compete with calibration worker threads for CPU. Tested under Linux (x64, aarch64) both with RT and non-RT scheduling, with sensor data arriving at ~3600Hz. Calibration completes normally and no longer results in a deadlocked process.
The autopilot stack the industry builds on.
About
PX4 is an open-source autopilot stack for drones and unmanned vehicles. It supports multirotors, fixed-wing, VTOL, rovers, and many more experimental platforms from racing quads to industrial survey aircraft. It runs on NuttX, Linux, and macOS. Licensed under BSD 3-Clause.
Why PX4
Modular architecture. PX4 is built around uORB, a DDS-compatible publish/subscribe middleware. Modules are fully parallelized and thread safe. You can build custom configurations and trim what you don't need.
Wide hardware support. PX4 runs on a wide range of autopilot boards and supports an extensive set of sensors, telemetry radios, and actuators through the Pixhawk ecosystem.
Developer friendly. First-class support for MAVLink and DDS / ROS 2 integration. Comprehensive SITL simulation, hardware-in-the-loop testing, and log analysis tools. An active developer community on Discord and the weekly dev call.
Vendor neutral governance. PX4 is hosted under the Dronecode Foundation, part of the Linux Foundation. Business-friendly BSD-3 license. No single vendor controls the roadmap.
Supported Vehicles
 Multicopter |
 Fixed Wing |
 VTOL |
 Rover |
…and many more: helicopters, autogyros, airships, submarines, boats, and other experimental platforms. These frames have basic support but are not part of the regular flight-test program. See the full airframe reference.
Quick Start
git clone https://github.com/PX4/PX4-Autopilot.git --recursive
cd PX4-Autopilot
make px4_sitl
Note
See the Development Guide for toolchain setup and build options.
Documentation & Resources
| Resource | Description |
|---|---|
| User Guide | Build, configure, and fly with PX4 |
| Developer Guide | Modify the flight stack, add peripherals, port to new hardware |
| Airframe Reference | Full list of supported frames |
| Autopilot Hardware | Compatible flight controllers |
| Release Notes | What's new in each release |
| Contribution Guide | How to contribute to PX4 |
Community
- Weekly Dev Call — open to all developers (Dronecode calendar)
- Discord — Join the Dronecode server
- Discussion Forum — PX4 Discuss
- Maintainers — see
MAINTAINERS.md - Contributor Stats — LFX Insights
Contributing
We welcome contributions of all kinds — bug reports, documentation, new features, and code reviews. Please read the Contribution Guide to get started.
Governance
The PX4 Autopilot project is hosted by the Dronecode Foundation, a Linux Foundation Collaborative Project. Dronecode holds all PX4 trademarks and serves as the project's legal guardian, ensuring vendor-neutral stewardship — no single company owns the name or controls the roadmap. The source code is licensed under the BSD 3-Clause license, so you are free to use, modify, and distribute it in your own projects.
