说明：  ST7920带中文字库液晶原码程序 12864 keil的，串行方式 编写时已经考虑到往avr上的移植了，spi可以用avr硬件的，也可以用io模拟，甚至可以用mega48的串口做spi主机 ，经过我的测试串行方式，在cs无效时，7920还是可以接受数据，导致显示被误改，如果spi上接了其它器件，小心使用。
(Driver with the original Chinese font LCD procedure code 12864 Keil. Serial way has been prepared to take into account the transplant avr, 20 avr hardware can be used, io can also use the simulation, or can even be done Serial mega48 20 mainframe, I have serial testing, cs in vain, 7920 can still receive data, resulting in the misuse of reform shows that if 20 on to other devices, careless use.)