Hi
Agree. Do you want the 17K PDF?
Cassie

> try to use the dedicated MT8870 IC. It is a DTMF decoder, with a 4-bit
> parallel output, and a strobe line. I use the strobe line to control the
> PIC INTR0 line. The AC characteristic of that IC is great, about 100 mV or
> so drives it already. It requires an 3.58 MHz XTAL and the oscillation can
> be used also to drive a PIC.
>
> Imre
>
>