BS2 DTMF Decoder

The project builded with the BASIC Stamp 2 OEM Module

My second project is a DTMF decoder using a CD22204E. The DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone's touch keys or, the keys used by some AMATER RADIO services.
 

The Basic Stamp 2 script:

' DTMF Decoder using a CD22204E ' by Denis Verreault ' ' {$STAMP BS2} ' {$PBASIC 2.5} t VAR Word INPUT 0 INPUT 1 INPUT 2 INPUT 3 INPUT 4 'used to detect the "D" key Main: t = IN0+(2*IN1)+(4*IN2)+(8*IN3) 'IF t=0 AND IN4=1 THEN GOTO D IF t=0 THEN GOTO main IF t<10 THEN DEBUG DEC t ELSE IF t=10 THEN DEBUG "0" IF t=11 THEN DEBUG "*" IF t=12 THEN DEBUG "#" IF t=13 THEN DEBUG "A" IF t=14 THEN DEBUG "B" IF t=15 THEN DEBUG "C" ENDIF t = 0 GOTO Main 'D: 'DEBUG "D" 'GOTO main END
Download the script

Download the source code for visual basic 6
 

The electronic Diagram:

Connection Diagram

The kit #28102 available at Abra-electronics