实现通过PC来控制fpga发出波形，波的形状和频率可通过PC控制，波形利用dds来发出，这是当时我做的电子测量的课程设计。-Fpga implementation given by PC to control the waveform, wave shape and frequency can be controlled through the PC, waveform using dds to send, this is when I do the electronic measurement