This is a quick list of things to try if tracking through phone sensors using the FreePIE app doesn't work:
- See whether your phone model has all of gyro, mag, and acc. You can use the CPU-Z app and uninstall it afterward.
- When mounting on headphones, position as far away from each magnet as possible. Try different configurations.
- The rotation is received through the system's API for position. The only room for improvement is phone hardware's sensor precision.
- There's a working freepie app as
.apkinside opentrack'scontribdirectory inside the installation directory.