The PX4 firmware is licensed generally under a permissive 3-clause BSD license. Contributions are required
to be made under the same license. Any exception to this general rule is listed below.

	/****************************************************************************
	 *
	 *   Copyright (c) 2012-2014 PX4 Development Team. All rights reserved.
	 *
	 * Redistribution and use in source and binary forms, with or without
	 * modification, are permitted provided that the following conditions
	 * are met:
	 *
	 * 1. Redistributions of source code must retain the above copyright
	 *    notice, this list of conditions and the following disclaimer.
	 * 2. Redistributions in binary form must reproduce the above copyright
	 *    notice, this list of conditions and the following disclaimer in
	 *    the documentation and/or other materials provided with the
	 *    distribution.
	 * 3. Neither the name PX4 nor the names of its contributors may be
	 *    used to endorse or promote products derived from this software
	 *    without specific prior written permission.
	 *
	 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
	 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
	 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
	 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
	 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
	 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
	 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
	 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	 * POSSIBILITY OF SUCH DAMAGE.
	 *
	 ****************************************************************************/


  - PX4 middleware: BSD 3-clause
  - PX4 flight control stack: BSD 3-clause
  - NuttX operating system: BSD 3-clause
  - Exceptions: Currently only this [400 LOC file](https://github.com/PX4/Firmware/blob/master/src/lib/external_lgpl/tecs/tecs.cpp) remains LGPL, but will be replaced with a BSD implementation.