该代码采用c5400dsp的汇编语言和c语言实现双音多频信号的产生于检测，用在设计的电话通信系统中，经过实际测试，效果很好，接口为同步串口。-c5400dsp of assembly language and c language DTMF signals generated in the detection, used in the design of the telephone communication system, throu