This tutorial explains the working of DTMF and how it can be embedded with Arduino based project. We have added working demo with two arduino based development board (R-Board & Arduino UNO).
1. Introduction:
Whenever we dial to a customer care service and there machine responses “Press 1 to do so”, “Press 2 to do so”. That is an application of DTMF. You can use DTMF in such application for example you want to switch on your AC 1 hour before you reach your home so that when you enter your home you get an air conditioned environment.
Thus DTMF is a low cost solution of controlling equipment from a remote location wirelessly
2. Hardware Required:
| S.No. | Item | Quantity |
| 1. | R-Board with FTDI or Arduino Board | 1 |
| 2. | DTMF Module | 1 |
| 3. | Male to female Jumpers | 6 |
| 3. | LED Array Led array is required to test DTMFmodule with out development board,if you dont want to test the same itis not required. | 1 |
3. Testing DTMF without microcontroller (Development Board)
To test Robo India DTMF module you need make the following circuit.
Schematic is here.
Connect your phone to DTMF module with the help of 3.5mm auxiliary cable. Increase volume of phone to the maximum. Now you may choose to call to the phone you have attached or you may download DTMF apps available at Android and Apple store.
After doing these, when you press any button, sound is generated and DTMF module decodes that sound to Digital output.
You will see above pattern on the LED board on the LEDs(4-7).
4. DTMF on Arduino
To see DTMF in actual action you will need to use it with microcontroller, here we are using it with Arduino.
4.1 make following circuit:
Schematic is here:
You can make this on Arduino UNO as following:
Schematic of above arrangement is here.
4.2 Now connect a phone to DTMF module with the help of 3.5mm Aux cable.
4.3 Connect Arduino UNO/R-Board with computer and you are ready with hardware part.
5. Programming
5.1 Copy/paste the following code and upload the same. (The complete code is explained in Comments, please go through the code.)
You may download this code (Arduino Sketch) from here
// Robo India Tutorial on using DTMF.
// www.roboindia.com
const int Q1 = 2; // Defining Digital Input Pins from DTMF Module
const int Q2 = 3;
const int Q3 = 4;
const int Q4 = 5;
int SoQ1 = 0; // Defining variable to store the status(HIGH/LOW) of above inputs.
int SoQ2 = 0;
int SoQ3 = 0;
int SoQ4 = 0;
int oldCon = 0; // Variable to know what was the last button pressed.
void setup(){
pinMode(Q1, INPUT); // Defining pins as input.
pinMode(Q2, INPUT);
pinMode(Q3, INPUT);
pinMode(Q4, INPUT);
Serial.begin(9600); // Setup Serial Communication.
Serial.print("ROBO INDIA\r\n");
Serial.print("roboindia.com\r\n");
}
void loop(){
SoQ1 = digitalRead(Q1); // Reading status of Input Pins. It can be LOW or HIGH
SoQ2 = digitalRead(Q2);
SoQ3 = digitalRead(Q3);
SoQ4 = digitalRead(Q4);
if(SoQ4==LOW && SoQ3==LOW && SoQ2==LOW && SoQ1==HIGH ) // Condition for Button 1. It is equal to Binary - 0001
{
if (oldCon!=1){ // Here we are testing that what was the last pressed button,
//We want actions to be done when current is not as the lastone.
Serial.println("1");
// Your Action goes here. // You can add your set of action here.
}
oldCon=1;
}
else if(SoQ4==LOW && SoQ3==LOW && SoQ2==HIGH && SoQ1==LOW ) // Condition for Button 2. It is equal to Binary - 0010
{
if (oldCon!=2){
Serial.println("2");
// Your Action goes here.
}
oldCon=2;
}
else if(SoQ4==LOW && SoQ3==LOW && SoQ2==HIGH && SoQ1==HIGH ) // Condition for Button 3. It is equal to Binary - 0011
{
if (oldCon!=3){
Serial.println("3");
// Your Action goes here.
}
oldCon=3;
}
else if(SoQ4==LOW && SoQ3==HIGH && SoQ2==LOW && SoQ1==LOW ) // Condition for Button 4. It is equal to Binary - 0100
{
if (oldCon!=4){
Serial.println("4");
// Your Action goes here.
}
oldCon=4;
}
else if(SoQ4==LOW && SoQ3==HIGH && SoQ2==LOW && SoQ1==HIGH ) // Condition for Button 5. It is equal to Binary - 0101
{
if (oldCon!=5){
Serial.println("5");
// Your Action goes here.
}
oldCon=5;
}
else if(SoQ4==LOW && SoQ3==HIGH && SoQ2==HIGH && SoQ1==LOW ) // Condition for Button 6. It is equal to Binary - 0110
{
if (oldCon!=6){
Serial.println("6");
// Your Action goes here.
}
oldCon=6;
}
else if(SoQ4==LOW && SoQ3==HIGH && SoQ2==HIGH && SoQ1==HIGH ) // Condition for Button 7. It is equal to Binary - 0111
{
if (oldCon!=7){
Serial.println("7");
// Your Action goes here.
}
oldCon=7;
}
else if(SoQ4==HIGH && SoQ3==LOW && SoQ2==LOW && SoQ1==LOW ) // Condition for Button 8. It is equal to Binary - 1000
{
if (oldCon!=8){
Serial.println("8");
// Your Action goes here.
}
oldCon=8;
}
else if(SoQ4==HIGH && SoQ3==LOW && SoQ2==LOW && SoQ1==HIGH ) // Condition for Button 9. It is equal to Binary - 1001
{
if (oldCon!=9){
Serial.println("9");
// Your Action goes here.
}
oldCon=9;
}
else if(SoQ4==HIGH && SoQ3==LOW && SoQ2==HIGH && SoQ1==LOW ) // Condition for Button 0 (10). It is equal to Binary - 1010
{
if (oldCon!=10){
Serial.println("0");
// Your Action goes here.
}
oldCon=10;
}
else if(SoQ4==HIGH && SoQ3==LOW && SoQ2==HIGH && SoQ1==HIGH ) // Condition for Button * (11). It is equal to Binary - 1011
{
if (oldCon!=11){
Serial.println("*");
// Your Action goes here.
}
oldCon=11;
}
else if(SoQ4==HIGH && SoQ3==HIGH && SoQ2==LOW && SoQ1==LOW ) // Condition for Button # (12). It is equal to Binary - 1100
{
if (oldCon!=12){
Serial.println("#");
// Your Action goes here.
}
oldCon=12;
}
else if(SoQ4==HIGH && SoQ3==HIGH && SoQ2==LOW && SoQ1==HIGH ) // Condition for Button A (13). It is equal to Binary - 1101
{
if (oldCon!=13){
Serial.println("A");
// Your Action goes here.
}
oldCon=13;
}
else if(SoQ4==HIGH && SoQ3==HIGH && SoQ2==HIGH && SoQ1==LOW ) // Condition for Button B (14). It is equal to Binary - 1110
{
if (oldCon!=14){
Serial.println("B");
// Your Action goes here.
}
oldCon=14;
}
else if(SoQ4==HIGH && SoQ3==HIGH && SoQ2==HIGH && SoQ1==HIGH ) // Condition for Button C (15). It is equal to Binary - 1111
{
if (oldCon!=15){
Serial.println("C");
// Your Action goes here.
}
oldCon=15;
}
else if(SoQ4==LOW && SoQ3==LOW && SoQ2==LOW && SoQ1==LOW ) // Condition for Button D (0). It is equal to Binary - 0000
{
if (oldCon!=0){
Serial.println("D");
// Your Action goes here.
}
oldCon=0;
}
delay(50); // Debounce Delay.
}
5.2 After uploading above mentioned code, Open serial monitor. And you will find following output.
The buttons you press it is displayed on serial monitor. In the codding section we have provided comments where you can add set of action with the input condition for your projects.
6. Actual Work
For the above project here is R-Board and Arduino UNO:
Original Arduino UNO with Robo India’s DTMF Module:
The testing output of this tutorial is:
if you have any query please write us at: support@roboindia.com
Thanks and Regards
Content Development Team
Robo India
http://roboindia.com