实现4×4键盘与51单片机的连接，有矩阵键盘模拟电子琴，4X4矩阵键盘(查表法)，矩阵键盘按键键值显示程序，4x4矩阵键盘实验(计算法)。-Achieve 4 × 4 with 51 single-chip keyboard connection, a matrix keyboard, analog keyboard, 4X4 matrix keyboard (look-up table), matrix keyboard keys display process Sequence, 4x4