使用2*4矩阵按键，外加两个独立按键，可以演奏一段小曲，或是使用来弹奏，包含程序图，仿真图，pcb图和原理图(Using 2*4 matrix buttons and two independent buttons, you can play a little tune, or use it to play, including program diagram, simulation diagram, PCB diagram and schematic diagram.)