实现dds功能，利用quartus软件， 子模块包括加法器，锁相环，date-rom 利用原图将各模块综合，利用ps2键盘控制频率及相位。-Dds realize functions, using Quartus software, sub-modules including the adder, phase-locked loop, date-rom image to the module using integrated, using ps2 keyboard to control