NYCRduCopter is a project mainly written in C++ and JAVA, it's free.
NYC Robotics QuadCopter Autopilot Software
This project contains an adaptation of the ArduPilot IMU functionality as taken from the AP_IMU library of the ArduCopter project.
Code in this project is intended to run on Arduino Uno hardware. It is designed to stream data from the IMU back to a computer using Serial.
IMPORTANT: Do NOT connect the 5-DOF to a +5V power supply. Powering with MORE than 3.6V may result in DAMAGE to the sensors! The Uno has a 3.3V output, which is fine to use.
Connect AREF to 3.3V for increased sensitivity (in ADC steps).
ADC - The original ArduCopter source is intended to be run on specialized hardware built around the Arduino Mega. It also uses an external 12-bit ADC connected to a serial port. It has been replaced by code that uses Uno's the onboard 10-bit ADC. Note that this required making some changes to constants used in the IMU for reading sensor data.
Hardware Serial - Some places in the code used the FastSerial library or hardware serial ports found on the Arduino Mega but not the Uno. These references were modified or removed as appropriate.
IMU DOF - ArduCopter has 3 gyro axes, but our IMU has only 2. This required a few small changes where sensor readings are taken and sensor data is stored.
EEPROM Storage - I haven't studied how this works yet, so I omitted it. ArduCopter has functions (under AP_Common) that allow persisting config or calibration data. This'll be nice in the future, but for now it wasn't needed.
board.h - Pin connections are defined here
calibration.h - constants related to particular sensors
IMU.h, APU_* - files from AP_IMU library, distilled to function on the Uno
ArducopterIMU.pde - main file with setup & loop. Just reads data from the IMU and pipes it out through Serial.
You'll need the ArduPilot libraries installed. They are included in the source distribution, along with installation instructions.
AP_Math is the only library used by the first version of this code.