It is possible to connect the DMF transceiver up to the external bus of the processor and use MOVX instructions to access its various functions. However it is equally valid to connect the control pin functions of this chip to normal port pins and let software perorm what is called bit-banging to control and monitor the DTMF chip. The latter connections would be VERY similar to the way common character mode LCD modules are connected to port bits using 4-bit bus mode.

If you search around this site via the...



... button to the left and look up the article Tutorial: Introduction to LCD Programming 2: Driving 4-bit Mode you will find some real helpful information that should give you some good ideas on connecting the DTMF chip.

Michael Karas