基于M16的字库液晶12864(st7920)的驱动，带有直接处理正负浮点数和正负整数数并且将数值显示的函数。硬件使用3根线，方便调试，更方便移植，有测试程序, 有详细说明。 -M16 character LCD 12864 (st7920)-based drive, with the function to deal directly with the positive and negative floating-point number and the number of positiv