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PCF8563详细驱动程序，使用飞思卡尔库函数

If it was necessary to have an estimate of angle for 360º of rotation, having the Y-axis measurement would be useful, but not necessary. With it, we could use trigonometry to find the inverse tangent of the two axis readings and calculate the angle. Without it, we can still use sine or cosine and the X-axis alone to figure out angle, since we know the magnitude of gravity. But trig kills processor time and is non-linear, so if it can be avoided, it should.