用新华龙的C8051F340单片机，实现的MODBUS RTU协议通信程序,New hualong the C8051F340 microcontroller, implementation of the MODBUS RTU protocol communication procedures

C8051f340的SPI学习程序。采用c语言编写，有利于新手学习。-C8051f340 the learning process of the SPI. Using c language is conducive to new learning.