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 top, then from the lower edge of the screen gradually appear. And so the cycle is more than