S08例程：本程序是显示模块的例程，所接器件为四位八段led数码管，其中PTB0-PTB3 与数码管的位选相连接，PTB4，PTB5与74LS164连接

stc串口通过74LS164扩展成串行输入并行输出的IO驱4线制动步进电机-STC serial port by74LS164expanded into the serial input parallel output IO drive 4stepper motor braking

74LS143与STM32F103连接，PA.0和PA.1控制A和B的收发，PB.0为时钟控制，连接clock。(The 74LS143 is connected to the STM32F103. PA.0 and PA.1 control the sending and receiving of A and B. PB.0 controls the clock and connects the clock.)