“使用AT90S4414芯片产生双音多频信号”

DTMF Generafor with AT9OS4414 chip

叙述了带有ＰＷＭ和ＳＲＡＮ的ＡＶＲ系列微控制器产生双音多频（ＤＴＭＦ）信号的方法。ＤＴＭＦ信号可用于电话机以传递拨号信令。ＤＴＭＦ信号是由两个不同频率合成的。表１显示出不同的频率ｆａ和ｆｂ合成ＤＴＭＦ音频信号。

This application note describes how DTMF (Dual-Tone Multiple Frequencies) signaling can be implemented using any AVR microcontroller with PWM and SRAM. Applications such as phones are using DTMF signals for transmitting dialing information. There are two frequencies added together to generate a valid DTMF signal,a low fre- quency (fb)and a high frequency (f a ). Table 1 shows how the different frequencies are mixed to form DTMF tones.