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By mlportersr
OK, I have one of your BNO080 boards and it is working great except that when I convert the quaternions to Euler angles, the Y axis always shows a pitch between 90 and -90 degrees. For Yaw and Roll (Z and X) I see a full 180 to -180 degrees, why is the Y axis limited? Is this intended?

By jremington
That is not a problem, it is a solution to a different problem. If you allow pitch angles >= 90 or <= -90, you can't even calculate the other angles using simple equations.

Angular systems are degenerate, meaning that if you allow a full 360 degrees rotation around each axis, there is always more than one way to represent the same absolute orientation.

And it gets worse. Look up "gimbal lock". Then there is the fact that the order of rotations matters. There are something like six different definitions for "Euler angles".