内容：三相步进电动机驱动程序

说明：步进脉冲从p3.2管脚输入（低电平有效），转动方向由p3.7管脚控制，

工作运行方式：三相六拍运行方式即 A-AB-B-BC-C-CA-A

输出：A、B、C三相输出分别对应P1.7、P1.6、P1.5 (各相输出为低电平)

片：STC89C52 时钟：11.0592MHZ-Content: Three-phase stepper motor driver Descr iption: Step pulse input from the p3.2 pin (active low), direction of rotation controlled by the p3.7 pin, working operation mode: three-phase six-run mode, namely the A-AB-B-BC-C-CA-A output: A, B, C three-phase output corresponding to the P1.7, P1.6, P1.5 (each phase output is low) films: STC89C52 clock: 11.0592 MHZ