说明：  基于AD9850的正弦波发生器的源码，运用单片机AT89S52对DDS芯片AD9850进行控制，通过键盘输入实现任意频率值的正弦波信号的发生
(AD9850 Based on the sine wave generator source code, the use of single-chip AT89S52 of DDS chip AD9850 is controlled through keyboard input achieve arbitrary frequency value of the sine wave signal happened)