先lcd屏幕中部开始显示4行的一首诗，在定时器控制下垂直滚动，直到整首诗逐渐从屏幕最上边消失，然后又从屏幕下沿逐渐出现。并如此循环不止-Middle of the screen started to show the first 4 lines of a poem, under the control of the vertical scroll in the timer, until the whole poem gradually disappear from the screen the