DTMF Decoder Using Only Arduino

1/*
2 
3 This code is a basic implementation of a DTMF decoder for   detecting the 16 character
4 DTMF code from the analog pin A0 and gives the decoded   output by checking for all the 
5 Upper and lower tones in the DTMF matrix and   gives us the corresponding number by turning
6 on the corresponding digital bit   for the numbers 0-9 and by Serially printing the rest of
7 the characters.
8   This work is entirely based on the Kevin Banks code found at
9  http://www.embedded.com/design/embedded/4024443/The-Goertzel-Algorithm
10   so full credit to him for his generic implementation and breakdown. 
11  The   Goertzel algorithm is long standing so see 
12  http://en.wikipedia.org/wiki/Goertzel_algorithm   for a full description.
13  It is often used in DTMF tone detection as an alternative   to the Fast 
14  Fourier Transform because it is quick with low overheard because   it
15  is only searching for a single frequency rather than showing the 
16  occurrence   of all frequencies.
17  * THIS CODE IS Made/modified by "Mian Mohammad Shoaib"   and  Released into the public domain.
18  * for any querries related to the code   feel free to ask at 
19  
20  MMSHOAIB8452@GMAIL.COM
21 */
22
23
24#include   <Goertzel.h>
25
26int sensorPin = A0; 
27const int N = 100;                       //it   is the number of samples code will take y0u can change for sensitivity and can if   large it can slow the arduino
28const float threshold = 2000;            //minimum   tone amplitude to be considered we can change it for more senstivity
29const float   sampling_freq = 8900;        //maximum detectable frequency is the sampling rate/2   and arduino uno with 16Mhz can support sampling upto 8900 Hz
30float x_frequencies[4];                   // make two arrays for holding x and y axis frequencies to be   detected
31float y_frequencies[4];
32
33void setup(){
34 pinMode(13, OUTPUT);                     //initalize blink led to show if any tone is detected
35 pinMode(2,   OUTPUT);                     //initialize 10 pins as output to show the dtmf outputs   from 2 to number 12 rest will be just derially printed to the monitor
36 pinMode(3,   OUTPUT);
37 pinMode(4, OUTPUT);
38 pinMode(5, OUTPUT);
39 pinMode(6, OUTPUT);
40   pinMode(7, OUTPUT);
41 pinMode(8, OUTPUT);
42 pinMode(9, OUTPUT);
43 pinMode(10,   OUTPUT);
44 pinMode(11, OUTPUT);
45 pinMode(12, OUTPUT);
46 
47  Serial.begin(9600);   
48
49x_frequencies[0]=1209;                //just initialize the arrays with   the x and y axis tone frequencies along with their row and colon number
50x_frequencies[1]=1336;
51x_frequencies[2]=1477;
52x_frequencies[3]=1633;
53
54y_frequencies[0]=697;
55y_frequencies[1]=770;
56y_frequencies[2]=852;
57y_frequencies[3]=941;
58}
59
60bool   detect_tone(float freq){
61
62Goertzel goertzel = Goertzel(freq, N, sampling_freq);         //initialize library function with the given sampling frequency no of samples   and target freq
63  goertzel.sample(sensorPin);                               //Will   take n samples          
64  float magnitude = goertzel.detect();                      //check   them for target_freq
65
66 if(magnitude>threshold){                                   //if   you're getting false hits or no hits adjust the threshold
67  digitalWrite(13,HIGH);                                     //blink led on 13 if a pulse is detected
68   delay(250);
69  digitalWrite(13,LOW);
70  Serial.print(freq);
71  Serial.print("\
72");
73   return true;
74 }
75  else
76    return false;
77}
78
79
80void print_number(int   row,int column){
81int number=0;
82if(row==0){                                             //find   the number corresponding to the found row and column
83  if(column== 0)
84  number=   1;
85  else if(column== 1)  
86  number= 2;
87  else if(column== 2)
88  number=   3;  
89  else if(column== 3)
90  number= 10;  
91}
92else if(row==1){
93  if(column==   0)
94  number= 4;  
95  else if(column== 1)
96  number= 5;    
97  else if(column==   2)
98  number= 6;    
99  else if(column== 3)
100  number= 11;    
101}
102else   if(row==2){
103  if(column== 0)
104  number= 7;  
105  else if(column== 1)
106  number=   8;    
107  else if(column== 2)
108  number= 9;    
109  else if(column== 3)  
110   number= 12;  
111}
112else if(row==3){
113  if(column== 0)
114  number= 14;  
115   else if(column== 1)
116  number= 0;    
117  else if(column== 2)
118  number=   15;    
119  else if(column== 3)
120  number= 13;    
121}
122
123if(number <10){
124digitalWrite((number+2),HIGH);
125Serial.print(number);
126}
127else   if(number ==10)
128Serial.print('A');
129else if(number ==11)
130Serial.print('B');
131else   if(number ==12)
132Serial.print('C');
133else if(number ==13)
134Serial.print('D');
135else   if(number ==14)
136Serial.print('*');
137else if(number ==15)
138Serial.print('#');
139Serial.print("\
140");
141delay(800);
142for(int   i=2;i<=12;i++){
143  digitalWrite(i,LOW);
144}
145}
146
147void loop(){
148int column=0,row=0;
149int   i=0;
150while(1){
151  if(detect_tone(x_frequencies[i]) == true){
152    column   = i;
153    break;
154  }
155  i++;
156if(i==4)
157i=0;
158}
159
160i=0;
161while(1){
162if(detect_tone(y_frequencies[i])   == true){
163    row = i;
164    break;
165  }
166   i++;
167if(i==4)
168i=0;
169}
170print_number(row,column);
171
172}

1/*
2 
3 This code is a basic implementation of a DTMF decoder for  detecting the 16 character
4 DTMF code from the analog pin A0 and gives the decoded  output by checking for all the 
5 Upper and lower tones in the DTMF matrix and  gives us the corresponding number by turning
6 on the corresponding digital bit  for the numbers 0-9 and by Serially printing the rest of
7 the characters.
8  This work is entirely based on the Kevin Banks code found at
9  http://www.embedded.com/design/embedded/4024443/The-Goertzel-Algorithm
10  so full credit to him for his generic implementation and breakdown. 
11  The  Goertzel algorithm is long standing so see 
12  http://en.wikipedia.org/wiki/Goertzel_algorithm  for a full description.
13  It is often used in DTMF tone detection as an alternative  to the Fast 
14  Fourier Transform because it is quick with low overheard because  it
15  is only searching for a single frequency rather than showing the 
16  occurrence  of all frequencies.
17  * THIS CODE IS Made/modified by "Mian Mohammad Shoaib"  and  Released into the public domain.
18  * for any querries related to the code  feel free to ask at 
19  
20  MMSHOAIB8452@GMAIL.COM
21 */
22
23
24#include  <Goertzel.h>
25
26int sensorPin = A0; 
27const int N = 100;                       //it  is the number of samples code will take y0u can change for sensitivity and can if  large it can slow the arduino
28const float threshold = 2000;            //minimum  tone amplitude to be considered we can change it for more senstivity
29const float  sampling_freq = 8900;        //maximum detectable frequency is the sampling rate/2  and arduino uno with 16Mhz can support sampling upto 8900 Hz
30float x_frequencies[4];                  // make two arrays for holding x and y axis frequencies to be  detected
31float y_frequencies[4];
32
33void setup(){
34 pinMode(13, OUTPUT);                    //initalize blink led to show if any tone is detected
35 pinMode(2,  OUTPUT);                     //initialize 10 pins as output to show the dtmf outputs  from 2 to number 12 rest will be just derially printed to the monitor
36 pinMode(3,  OUTPUT);
37 pinMode(4, OUTPUT);
38 pinMode(5, OUTPUT);
39 pinMode(6, OUTPUT);
40  pinMode(7, OUTPUT);
41 pinMode(8, OUTPUT);
42 pinMode(9, OUTPUT);
43 pinMode(10,  OUTPUT);
44 pinMode(11, OUTPUT);
45 pinMode(12, OUTPUT);
46 
47  Serial.begin(9600);  
48
49x_frequencies[0]=1209;                //just initialize the arrays with  the x and y axis tone frequencies along with their row and colon number
50x_frequencies[1]=1336;
51x_frequencies[2]=1477;
52x_frequencies[3]=1633;
53
54y_frequencies[0]=697;
55y_frequencies[1]=770;
56y_frequencies[2]=852;
57y_frequencies[3]=941;
58}
59
60bool  detect_tone(float freq){
61
62Goertzel goertzel = Goertzel(freq, N, sampling_freq);        //initialize library function with the given sampling frequency no of samples  and target freq
63  goertzel.sample(sensorPin);                               //Will  take n samples          
64  float magnitude = goertzel.detect();                      //check  them for target_freq
65
66 if(magnitude>threshold){                                   //if  you're getting false hits or no hits adjust the threshold
67  digitalWrite(13,HIGH);                                    //blink led on 13 if a pulse is detected
68  delay(250);
69  digitalWrite(13,LOW);
70  Serial.print(freq);
71  Serial.print("\
72");
73  return true;
74 }
75  else
76    return false;
77}
78
79
80void print_number(int  row,int column){
81int number=0;
82if(row==0){                                             //find  the number corresponding to the found row and column
83  if(column== 0)
84  number=  1;
85  else if(column== 1)  
86  number= 2;
87  else if(column== 2)
88  number=  3;  
89  else if(column== 3)
90  number= 10;  
91}
92else if(row==1){
93  if(column==  0)
94  number= 4;  
95  else if(column== 1)
96  number= 5;    
97  else if(column==  2)
98  number= 6;    
99  else if(column== 3)
100  number= 11;    
101}
102else  if(row==2){
103  if(column== 0)
104  number= 7;  
105  else if(column== 1)
106  number=  8;    
107  else if(column== 2)
108  number= 9;    
109  else if(column== 3)  
110  number= 12;  
111}
112else if(row==3){
113  if(column== 0)
114  number= 14;  
115  else if(column== 1)
116  number= 0;    
117  else if(column== 2)
118  number=  15;    
119  else if(column== 3)
120  number= 13;    
121}
122
123if(number <10){
124digitalWrite((number+2),HIGH);
125Serial.print(number);
126}
127else  if(number ==10)
128Serial.print('A');
129else if(number ==11)
130Serial.print('B');
131else  if(number ==12)
132Serial.print('C');
133else if(number ==13)
134Serial.print('D');
135else  if(number ==14)
136Serial.print('*');
137else if(number ==15)
138Serial.print('#');
139Serial.print("\
140");
141delay(800);
142for(int  i=2;i<=12;i++){
143  digitalWrite(i,LOW);
144}
145}
146
147void loop(){
148int column=0,row=0;
149int  i=0;
150while(1){
151  if(detect_tone(x_frequencies[i]) == true){
152    column  = i;
153    break;
154  }
155  i++;
156if(i==4)
157i=0;
158}
159
160i=0;
161while(1){
162if(detect_tone(y_frequencies[i])  == true){
163    row = i;
164    break;
165  }
166   i++;
167if(i==4)
168i=0;
169}
170print_number(row,column);
171
172}