飞思卡尔MC9S12XS128之锁相环PLL 单片机 三 272011通过设置XS128的锁相环，可以方便改变内部总线频率，轻松实现超频。下面是16MHz~120MHz的设置函数，后面有各寄存器用法。-The phase-locked loop PLL chip Freescale MC9S12XS128 three 272,011 PLL by setting the XS128, you can easily change the internal bus frequency, easy