L297 chip generates pulse phase sequence signals of which the pulse width is adjustable. The signals are the input ones of dual bridge driving circuit and drive the stepper motor after amplification.
L 297芯片产生脉宽可调的脉冲相序信号，该信号作为双极性桥式功率驱动电路的输入信号，放大后驱动步进电机。
2
The 'h' Bridge design built on one of the existing PCB's, basically just one complete controller circuit and two output stages linked together at the input of the optocouplers.
' h '桥梁设计建立在一个现有的印刷电路板的，基本上只是一个完整的控制器电路和两个输出阶段联系在一起，在输入光电耦合器。