用SPI总线将两块实验电路板连接起来。作为SPI主机的PIC单片机读取其所在的实验电路板上的按键值，判断6只按键中的哪一只被按下，并将按键编号通过SPI总线发送给作为从机的PIC单片机。从机得到按键编号后点亮从机所在电路板上对应的发光二极管，并将收到的按键编号重新发还给主机。主机收到后也将所在电路板上对应的发光二极管点亮。-Two breadboard connection with the SPI bus. Read key value of its experimental circuit board as a the SPI host of PIC microcontroller to determine which six keys only press and key ID send through the SPI bus as a slave PIC microcontroller. Key ID from the machine lit from the light-emitting diode, corresponding to the machine where the circuit board and will be returned to the host again received key number. The host receives the circuit board where the corresponding LED lights.