测量转速，使用霍尔传感器，被测轴安装有12只磁钢，即转轴每转一周，产生12个脉冲，要求将转速值（转/分）显示在数码管上。-Measurement speed, the use of Hall sensors, the measured axial magnet 12 is installed, that is, to a week of each axis to produce 12 pulses requested speed val