12864 ASM驱动程序接着要做的事就是指定我们的图片要从哪里写入（即写入的XY坐标，这个是最关键，也是最难理解的部分）。因为我们这里是显示一整个画面的图片，所以我们就从12864的第一个点开始显示。那这个点的坐标是怎么定位的呢？我们往这个点写入数据后，要是接着再写数据，-Then to do is specify where to write from our picture (that is, write the XY coordinates of the Is the most critical part is the hardest to understand). Because we are here is to show an entire screen map Film, so we first point from the 12864 beginning to show. That the coordinates of this point is how determined Bit of it? We write data to this point, if followed by write data, that coordinates what would happen Change? First we must clarify what is 12864 how to write data to the GDRAM (graphics display Display RAM) to go. 12864 (ST7920 driver chips) to the screen is divided into two parts (as Figure in the vertical coordinate is divided into two parts of 00 ~ 1F). When we wrote the LCD after the coordinate values ​　​　(how Why write back would say), ST7920 control chip on the LCD screen of the control process can use the following diagram Pieces to represent: (The following photograph picture a little later found the problem ... it s here in the horizontal c