Tone Decoder

Using Tone Decoder for microcontroller,telephone interface,remote control is one advantage, because DTMF (Dual Tone Multi Frequency) is reliable from noise and error, here i describle how to using tone decoder :
I'm using CM8870 DTMF decoder from california device, it can decode fron audio signal to 4 bit digital data in cheaper price :)

the picture above i describle :
pin 11 to 14 is output data, Q1 to Q4, Q4 is the MSB.
right table is output configuration
StD in pin 15 is active high, it will be high if Indicates that valid frequencies have been present/absent for the required guard time, thus constituting a valid signal.