Metal Detector

1// Arduino based metal detector
2// (C)Dzl july 2013
3
4// http://dzlsevilgeniuslair.blogspot.dk
5
6/   Connect search coil oscillator (20-200kHz) to pin 5
7
8// Connect piezo between   pin 13 and GND
9
10// Connect NULL button between pin 12 anf GND
11
12// REMEMBER   TO PRESS NULL BUTTON AFTER POWER UP!!
13
14#define SET(x,y) (x |=(1<
15
16#define   CLR(x,y) (x &= (~(1<
17
18#define CHK(x,y) (x & (1<
19
20#define TOG(x,y) (x^=(1<
21
22unsigned   long t0=0; //-Last time
23
24int t=0; //-time between ints
25
26unsigned char   tflag=0; //-Measurement ready flag
27
28float SENSITIVITY= 1000.0; //-Guess what
29
30//-Generate   interrupt every 1000 oscillations of the search coil
31
32SIGNAL(TIMER1_COMPA_vect)
33
34{
35
36OCR1A+=1000;
37
38t=micros()-t0;
39
40t0+=t;
41
42tflag=1;
43
44}
45
46void   setup()
47
48{
49
50Serial.begin(9600);
51
52pinMode(13,OUTPUT); //-piezo   pin
53
54digitalWrite(12,HIGH); //-NULL SW. pull up
55
56//-Set up counter1   to count at pin 5
57
58TCCR1A=0;
59
60TCCR1B=0x07;
61
62SET(TIMSK1,OCF1A);
63
64}
65
66//-Float   ABS
67
68float absf(float f)
69
70{
71
72if(f<0.0)
73
74return -f;
75
76else
77
78return   f;
79
80}
81
82int v0=0; //-NULL value
83
84float f=0; //-Measurement value
85
86unsigned   int FTW=0; //-Click generator rate
87
88unsigned int PCW=0; //-Click generator   phase
89
90unsigned long timer=0; //-Click timer
91
92void loop()
93
94{
95
96if(tflag)
97
98{
99
100if(digitalRead(12)==LOW)   //-Check NULL SW.
101
102v0=t; //-Sample new null value
103
104f=f*0.9+absf(t-v0)*0.1;   //-Running average over 10 samples
105
106tflag=0; //-Reset flag
107
108float clf=f*SENSITIVITY;   //-Convert measurement to click frequency
109
110if(clf>10000)
111
112clf=10000;
113
114FTW=clf;
115
116Serial.println(f);
117
118}
119
120//-Click   generator
121
122if(millis()>timer)
123
124{
125
126timer+=10;
127
128PCW+=FTW;
129
130if(PCW&0x8000)
131
132{
133
134digitalWrite(13,HIGH);
135
136PCW&=0x7fff;
137
138}
139
140else
141
142digitalWrite(13,LOW);
143
144}
145
146}

1// Arduino based metal detector
2// (C)Dzl july 2013
3
4// http://dzlsevilgeniuslair.blogspot.dk
5
6/
7  Connect search coil oscillator (20-200kHz) to pin 5
8
9// Connect piezo between
10  pin 13 and GND
11
12// Connect NULL button between pin 12 anf GND
13
14// REMEMBER
15  TO PRESS NULL BUTTON AFTER POWER UP!!
16
17#define SET(x,y) (x |=(1<
18
19#define
20  CLR(x,y) (x &= (~(1<
21
22#define CHK(x,y) (x & (1<
23
24#define TOG(x,y) (x^=(1<
25
26unsigned
27  long t0=0; //-Last time
28
29int t=0; //-time between ints
30
31unsigned char
32  tflag=0; //-Measurement ready flag
33
34float SENSITIVITY= 1000.0; //-Guess what
35
36//-Generate
37  interrupt every 1000 oscillations of the search coil
38
39SIGNAL(TIMER1_COMPA_vect)
40
41{
42
43OCR1A+=1000;
44
45t=micros()-t0;
46
47t0+=t;
48
49tflag=1;
50
51}
52
53void
54  setup()
55
56{
57
58Serial.begin(9600);
59
60pinMode(13,OUTPUT); //-piezo
61  pin
62
63digitalWrite(12,HIGH); //-NULL SW. pull up
64
65//-Set up counter1
66  to count at pin 5
67
68TCCR1A=0;
69
70TCCR1B=0x07;
71
72SET(TIMSK1,OCF1A);
73
74}
75
76//-Float
77  ABS
78
79float absf(float f)
80
81{
82
83if(f<0.0)
84
85return -f;
86
87else
88
89return
90  f;
91
92}
93
94int v0=0; //-NULL value
95
96float f=0; //-Measurement value
97
98unsigned
99  int FTW=0; //-Click generator rate
100
101unsigned int PCW=0; //-Click generator
102  phase
103
104unsigned long timer=0; //-Click timer
105
106void loop()
107
108{
109
110if(tflag)
111
112{
113
114if(digitalRead(12)==LOW)
115  //-Check NULL SW.
116
117v0=t; //-Sample new null value
118
119f=f*0.9+absf(t-v0)*0.1;
120  //-Running average over 10 samples
121
122tflag=0; //-Reset flag
123
124float clf=f*SENSITIVITY;
125  //-Convert measurement to click frequency
126
127if(clf>10000)
128
129clf=10000;
130
131FTW=clf;
132
133Serial.println(f);
134
135}
136
137//-Click
138  generator
139
140if(millis()>timer)
141
142{
143
144timer+=10;
145
146PCW+=FTW;
147
148if(PCW&0x8000)
149
150{
151
152digitalWrite(13,HIGH);
153
154PCW&=0x7fff;
155
156}
157
158else
159
160digitalWrite(13,LOW);
161
162}
163
164}