VHDL实现谐波检测信号发生的DDS. 同时发出正弦波，三角波，正弦波2倍频后的方波。波形频率相位可调。-VHDL implementation of harmonic detection signal of the DDS. Also issued a sine wave, triangle wave, sine wave, after square-wave frequency 2. Phase adjustable frequency waveform.