Hello I'm a bit new to Arduino and electronics. I'm using an Arduino Uno to hack some telephones to use DTMF to communicate between two arduinos across phone lines (much like the cellphone controlled robots). I am using a MT8870DE DTMF tone decoder right now (though I have some MT8888's). It generates a binary code on four output pins. Everything is working fine--the chip generates binary code when I send a tone from the phone--but the arduino can't read it.
I am getting just enough power to turn on an LED but apparently not enough for the digital pin to see it.
Here are the things that I have tried:
-Having the chip send binary to LED lights --Works--the lights turn on
-Having the chip send binary to arduino analog pin --low reads 0-40, high reads 1020-1022 (only about 700 if the LED is plugged in)
-Send the signal to a HEX Inverter (DM74LS04) --Works on an LED but gives the same (though opposite) values to the analog pin--and still does not trip HIGH for digital
-Send the signal to a transister (PN2222 and TIP120) --not enough power to trip the transistor
Running out of ideas--I'm getting ready to just read this thing from analog (messy code) or do an optic coupler (just stupid)! It seems like it should be so simple!