open-headtracker versions (http://www.rcgroups.com/forums/showthread.php?t=1677559&page=207)
all founded forks of original DIY_Headtracker ( in DIY_Headtracker_firmware_orig )
DIY_headtracker-8mhz - port to 8mhz Arduino (as is) and others for different sensors (as is)
main one: DIY_Headtracker_firmware_fastserial - changed to FastSerial library with printf_P, uses ATAN2 (no more NAN!), add noise filter and some cleanup
- sensor timer moved from timer0 to timer2 - so we can use millis()!
- odd slow Wire library changed to fast I2C library
- I2C library altered to speed up and reduce size
- added full compass calibration with hard-iron and soft-iron corrections
- addede Four Order filter to accel data
- all code refactored to fit all the above
- calculations optimized so now measure & calculations uses only 4ms
- gyro filter changed from 98Hz to 20Hz
- It works!