由于RS232的电平与Arduino Mega 2560的接口电平不能兼容，所以就需要进行电平的转换，即进行串口转换模块的设计，本文选择利用ATMEGA16U2-MU模块来做电平转换，将上位机的指令通过此模块发给下位机-Since the RS232 level is not compatible with the Arduino Mega 2560 interface level, so we need to level conversion, that is designed to seri

melzi 3D打印机的硬件电路原理图，有主机、传感器和驱动电路-Hardware circuit diagram melzi 3D printer, there are a host, and the sensor driver circuit

EM78P451 SPI官方使用程序，内涵主机模式、从机模式已经.INC头文件。(EM78P451 SPI The official use program, the connotations of the host mode, the slave mode has.INC header file.)