文中设计基于AVR单片机AT90S8515和DDS芯片AD9835的信号发生器的硬件电路，给出AD9835工作流程图和AT90S8515串行加载AD9835芯片的时序图。-In this paper，the design of a signal generator circuit based on AVR microprocessor AT90S8515 and DDS chip AD9835 is introduced，illustrated the working diagram of AD9835，presented the procedure of AT90S8515 serial loading DDS chip AD9835.