STM32驱动ch395_4个socket连接

代码说明：

  main.c已详尽注释连接的引脚 和 调试助手参数。STM32分别以串口,硬件SPI,模拟并口驱动CH395,4个socket连接, 原路返回上位机发送的数据。串口模式支持更改工作波特率，硬件SPI速率最高36MHz, 模拟并口较快，这三种模式支持在stm32任意型号下。(Main.c has commented on pins and debugging assistant parameters in detail. STM32 drives CH395 and 4 sockets by serial port, hardware SPI and analog parallel port respectively, and returns the data sent by the host computer in the original way. Serial mode supports changing working baud rate. Hardware SPI rate is up to 36MHz and analog parallel port is fast. These three modes support any model of stm32.)