DTMF DECODERS Are used to detect DTMF TONES Genrated by mobile phone DTMF Keypad.
In this project we are going to decode the DTMF Tones into 4bit Output and this output is given to the arduino which detects the keypress and displays it on LCD

Step 1: Components Used

The components that I have used are easily available locally in most of the cities or you can also buy it online

1 x Arduino UNO
1 x 16x2 Alphanumeric LCD
1 x Bread Board
1 x MT8870 DTMF Decoder IC
Jumper Wires Male to Male
1 x Crystal 3.579Mhz
1 x 390k Resistor
2 x 100k Resistor
2 x 0.1uf Ceramic Capacitor
1 x 10K Variable resistor
1 x 3.5mm Audio Jack

Step 2: Circuit Diagram

Use the above Circuit Diagram and build the circuit.You can change it according to your need

Step 3: Giving DTMF Input to Circuit

The input is given by a mobile phone with a 3.5mm jack which provides the DTMF signals to MT8870 decoder

Step 4: Programming the Arduino

I used USBasp to program arduino u directly program it using usb it is better to use usbasp if you are building the circuit on breadboard

Step 5: Arduino Code

Use the code to program arduino
it uses hex codes for numbers pressed on dialpad of mobile

The Hex Codes For Keypress Are As Follows
1 = 0x01
2 = 0x02
3 = 0x03
4 = 0x04
5 = 0x05
6 = 0x06
7 = 0x07
8 = 0x08
9 = 0x09
0 = 0x0A
# = 0x0C