51单片机及其C语言程序开发实例,介绍了51单片机常用的模块电路设计与实现，主要模块有键盘、LCD显示、A/D转换、D/A转换、I2C总线应用、语音、实时时钟、红外、USB、步进电机、数字锁相环、串口通信、DDS等-51 microcontroller C language program development instance, introduced 51 single-chip module circuit design and implementation of the main mod

本源码针对USB继电器，使PC通过USB连接继电器从而控制电路开、关。-The source for the USB relay, so the relay to control circuit connected to the PC on and off via USB.

SMT32的9路max31855电路，usb CH340(ON SMT32 9 max31855,usb CH340 connect computor)