这个文件包含A3972的protel99 原理图和PCB图，经过大量产品验证。配合本人以前上传的AA3972源程序，希望可以为初学入门者提供参考。-This file contains the protel99 schematic and PCB in A3972 after a large number of product validation. With the the AA3972 source I previously uploaded, I hope to provide a ref

这段程序是步进电机的细分驱动动程序，驱动芯片是A3972. -This process is the breakdown of stepper motor driver driver driver chip is the A3972.