Based on the datasheet, HMC5583L has 160Hz output rate and produce three axis direction angle data, X, Y, and Z. It can measure diversion from Earth magnet field with 1° to 2° accuracy. Does that means that the "heading" direction always point to the North perpendicular to vertical orientation or it is slightly point downward? Does it also has measurement drift overtime? Is it reasonable to use it alone as orientation detector or it needs to be orchestrated with other sensors?
I understand that gyro + accelerometer module is more suitable than this, but there is also the tricky drift to deal with if we want to detect the orientation overtime. I'm merely considering alternatives.