说明：  LPC1768控制ST7920的显示屏，串行模式，不知道为什么，必须写第二次数据才能正常显示，发上来给大家参考下。
(LPC1768 control ST7920 display, serial mode, do not know why, we must write a second data to the normal display, made up for everyone to refer to the next.)