在28335的eQEP模块的reference Guide一书中，有个计算转速的公式：
v(k)=x(k)-x(k-1)/T
其说明如下：
Estimation based on Equation 1 has an inherent accuracy limit directly related to the resolution of the
position sensor and the unit time period T. For example, consider a 500-line per revolution quadrature
encoder with a velocity calculation rate of 400 Hz. When used for position the quadrature encoder gives a
four-fold increase in resolution, in this case, 2000 counts per revolution. The minimum rotation that can be
detected is therefore 0.0005 revolutions, which gives a velocity resolution of 12 rpm when sampled at 400
Hz. While this resolution may be satisfactory at moderate or high speeds, e.g. 1% error at 1200 rpm, it
would clearly prove inadequate at low speeds. In fact, at speeds below 12 rpm, the speed estimate would
erroneously be zero much of the time
在这里我没看明白的有两点：
1、最小可检测圈速为0.0005是如何计算的？
2、速度精度12rpm是如何计算的？
求教了
