Magnetic Field Meter range +- 200mT (milliTesla)

A stable instrument with display, LED and buzzer to feel the Magnetic Field live.

Mar 30, 2022

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5430 views

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3 respects

environmental sensing

debugging tools

data collection

Components and supplies

Arduino Nano R3

Project description

Code

Arduino Sketch

arduino

1/*
2 This sketch acts as a Magnetic Field Meter, by Marco Zonca, 3/2021
3  Arduino Nano as 5V MPU, UGN3503UA magnetic sensor, i2c Oled 128x32 display, a LED,
4  one button, an active buzzer and a few resistors;
5
6 Magnetic Field Meter,  output in milliTesla (mT)
7  
8 from sensor +- 1.3 mV = +- 1 Gauss = +- 0.1  mT
9 from sensor 2.5V = 0 (0-2.5V = -2500 to 0 mV, 2.5-5V = 0 to 2500mV)  
10*/
11
12#include  <Wire.h>
13#include <Adafruit_SSD1306.h>
14
15Adafruit_SSD1306 display = Adafruit_SSD1306  (128, 32, &Wire, -1);
16
17float aVal=0;
18float aZero=0;
19float aRead=0;
20float  VL=0;
21float Gauss=0;
22float mTesla=0;
23float fTot=0;
24float fNr=0;
25float  fMax=0;
26float fMin=0;
27float fAvr=0;
28
29unsigned long fprevMillis=0;
30
31const  unsigned long fMillis=500;  // update display and average calc every 0.5 seconds
32const  int aValPin=14;
33const int aLedPin=10;
34const int aBuzPin=9;
35const int aButton=15;
36
37String  mT = "  -0.0 mT";
38
39void setup() {
40  //Serial.begin(9600);
41  display.begin(SSD1306_SWITCHCAPVCC,  0x3C); // Display Address 0x3C for 128x32 pixels
42  mT.reserve(20);
43}  //setup()
44
45void  loop() {
46  aRead=analogRead(aValPin);
47  if (aZero==0) aZero=aRead;  // initial  auto zero
48  if (digitalRead(aButton)==LOW) aZero=aRead;  // forced zero with  button
49  aVal=(map(aRead,0,1023,0,5000)-map(aZero,0,1023,0,5000)) / 1.3;  //  to milliVolt, to Gauss
50  if (aVal != 0) {
51    fTot=fTot+aVal;
52    fNr=fNr+1;
53  }
54  if (aVal>fMax) fMax=aVal;  // mem max
55  if (aVal<fMin) fMin=aVal;  //  mem min
56  if (millis() > (fMillis+fprevMillis)) showVal(); 
57}  //loop()
58
59void  showVal() {
60  if (fMax != 0) {
61    fTot=fTot-fMax;  // average without max
62    fNr=fNr-1;    
63  }
64  if (fMin != 0) {
65    fTot=fTot-fMin;  // average  without min
66    fNr=fNr-1;    
67  }
68  if (fNr > 0) {
69    aVal=fTot/fNr;  // average value
70  } else {
71    aVal=0;
72  }
73  if (aVal != aZero) {
74    Gauss=aVal;
75    mTesla=Gauss/10;  // to milliTesla
76    VL=abs((aVal) /  10);
77    if (VL>255) VL=255;
78    analogWrite(aLedPin,VL);  // lights led
79    analogWrite(aBuzPin,VL);  // beeps buz
80    //Serial.print(roundOneDec(mTesla));
81    //Serial.println("mT");
82  } else {
83    Gauss=0;
84    mTesla=0;
85    analogWrite(aLedPin,0);  // off led
86    analogWrite(aBuzPin,0);  // off buz
87  }
88  display.clearDisplay();  // output to display
89  display.setTextColor(SSD1306_WHITE);
90  display.setTextSize(1);
91  display.setCursor(1,1);
92  display.print("Magnetic  Field Meter");
93  display.setTextSize(2);
94  display.setCursor(8,16);
95  mT="      "+String(roundOneDec(mTesla),1)+" mT";
96  display.print(mT.substring(mT.length()-9));  // right alignment
97  display.display();  
98  
99  fprevMillis=millis();
100  fTot=0;
101  fNr=0;
102  fMin=0;
103  fMax=0;
104}  //showVal()
105
106float roundOneDec(float  f) {
107  float y, d;
108  y = f*10;
109  d = y - (int)y;
110  y = (float)(int)(f*10)/10;
111  if (d >= 0.5) {
112    y += 0.1;
113   } else {
114    if (d < -0.5) {
115    y  -= 0.1;
116  }
117  }
118  return y;
119}  //roundOneDec()
120

/*
 This sketch acts as a Magnetic Field Meter, by Marco Zonca, 3/2021
  Arduino Nano as 5V MPU, UGN3503UA magnetic sensor, i2c Oled 128x32 display, a LED,
  one button, an active buzzer and a few resistors;

 Magnetic Field Meter,  output in milliTesla (mT)
  
 from sensor +- 1.3 mV = +- 1 Gauss = +- 0.1  mT
 from sensor 2.5V = 0 (0-2.5V = -2500 to 0 mV, 2.5-5V = 0 to 2500mV)  
*/

#include  <Wire.h>
#include <Adafruit_SSD1306.h>

Adafruit_SSD1306 display = Adafruit_SSD1306  (128, 32, &Wire, -1);

float aVal=0;
float aZero=0;
float aRead=0;
float  VL=0;
float Gauss=0;
float mTesla=0;
float fTot=0;
float fNr=0;
float  fMax=0;
float fMin=0;
float fAvr=0;

unsigned long fprevMillis=0;

const  unsigned long fMillis=500;  // update display and average calc every 0.5 seconds
const  int aValPin=14;
const int aLedPin=10;
const int aBuzPin=9;
const int aButton=15;

String  mT = "  -0.0 mT";

void setup() {
  //Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC,  0x3C); // Display Address 0x3C for 128x32 pixels
  mT.reserve(20);
}  //setup()

void  loop() {
  aRead=analogRead(aValPin);
  if (aZero==0) aZero=aRead;  // initial  auto zero
  if (digitalRead(aButton)==LOW) aZero=aRead;  // forced zero with  button
  aVal=(map(aRead,0,1023,0,5000)-map(aZero,0,1023,0,5000)) / 1.3;  //  to milliVolt, to Gauss
  if (aVal != 0) {
    fTot=fTot+aVal;
    fNr=fNr+1;
  }
  if (aVal>fMax) fMax=aVal;  // mem max
  if (aVal<fMin) fMin=aVal;  //  mem min
  if (millis() > (fMillis+fprevMillis)) showVal(); 
}  //loop()

void  showVal() {
  if (fMax != 0) {
    fTot=fTot-fMax;  // average without max
    fNr=fNr-1;    
  }
  if (fMin != 0) {
    fTot=fTot-fMin;  // average  without min
    fNr=fNr-1;    
  }
  if (fNr > 0) {
    aVal=fTot/fNr;  // average value
  } else {
    aVal=0;
  }
  if (aVal != aZero) {
    Gauss=aVal;
    mTesla=Gauss/10;  // to milliTesla
    VL=abs((aVal) /  10);
    if (VL>255) VL=255;
    analogWrite(aLedPin,VL);  // lights led
    analogWrite(aBuzPin,VL);  // beeps buz
    //Serial.print(roundOneDec(mTesla));
    //Serial.println("mT");
  } else {
    Gauss=0;
    mTesla=0;
    analogWrite(aLedPin,0);  // off led
    analogWrite(aBuzPin,0);  // off buz
  }
  display.clearDisplay();  // output to display
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(1,1);
  display.print("Magnetic  Field Meter");
  display.setTextSize(2);
  display.setCursor(8,16);
  mT="      "+String(roundOneDec(mTesla),1)+" mT";
  display.print(mT.substring(mT.length()-9));  // right alignment
  display.display();  
  
  fprevMillis=millis();
  fTot=0;
  fNr=0;
  fMin=0;
  fMax=0;
}  //showVal()

float roundOneDec(float  f) {
  float y, d;
  y = f*10;
  d = y - (int)y;
  y = (float)(int)(f*10)/10;
  if (d >= 0.5) {
    y += 0.1;
   } else {
    if (d < -0.5) {
    y  -= 0.1;
  }
  }
  return y;
}  //roundOneDec()

Arduino Sketch

arduino

1/*
2 This sketch acts as a Magnetic Field Meter, by Marco Zonca, 3/2021
3   Arduino Nano as 5V MPU, UGN3503UA magnetic sensor, i2c Oled 128x32 display, a LED,
4   one button, an active buzzer and a few resistors;
5
6 Magnetic Field Meter,   output in milliTesla (mT)
7  
8 from sensor +- 1.3 mV = +- 1 Gauss = +- 0.1   mT
9 from sensor 2.5V = 0 (0-2.5V = -2500 to 0 mV, 2.5-5V = 0 to 2500mV)  
10*/
11
12#include   <Wire.h>
13#include <Adafruit_SSD1306.h>
14
15Adafruit_SSD1306 display = Adafruit_SSD1306   (128, 32, &Wire, -1);
16
17float aVal=0;
18float aZero=0;
19float aRead=0;
20float   VL=0;
21float Gauss=0;
22float mTesla=0;
23float fTot=0;
24float fNr=0;
25float   fMax=0;
26float fMin=0;
27float fAvr=0;
28
29unsigned long fprevMillis=0;
30
31const   unsigned long fMillis=500;  // update display and average calc every 0.5 seconds
32const   int aValPin=14;
33const int aLedPin=10;
34const int aBuzPin=9;
35const int aButton=15;
36
37String   mT = "  -0.0 mT";
38
39void setup() {
40  //Serial.begin(9600);
41  display.begin(SSD1306_SWITCHCAPVCC,   0x3C); // Display Address 0x3C for 128x32 pixels
42  mT.reserve(20);
43}  //setup()
44
45void   loop() {
46  aRead=analogRead(aValPin);
47  if (aZero==0) aZero=aRead;  // initial   auto zero
48  if (digitalRead(aButton)==LOW) aZero=aRead;  // forced zero with   button
49  aVal=(map(aRead,0,1023,0,5000)-map(aZero,0,1023,0,5000)) / 1.3;  //   to milliVolt, to Gauss
50  if (aVal != 0) {
51    fTot=fTot+aVal;
52    fNr=fNr+1;
53   }
54  if (aVal>fMax) fMax=aVal;  // mem max
55  if (aVal<fMin) fMin=aVal;  //   mem min
56  if (millis() > (fMillis+fprevMillis)) showVal(); 
57}  //loop()
58
59void   showVal() {
60  if (fMax != 0) {
61    fTot=fTot-fMax;  // average without max
62     fNr=fNr-1;    
63  }
64  if (fMin != 0) {
65    fTot=fTot-fMin;  // average   without min
66    fNr=fNr-1;    
67  }
68  if (fNr > 0) {
69    aVal=fTot/fNr;   // average value
70  } else {
71    aVal=0;
72  }
73  if (aVal != aZero) {
74     Gauss=aVal;
75    mTesla=Gauss/10;  // to milliTesla
76    VL=abs((aVal) /   10);
77    if (VL>255) VL=255;
78    analogWrite(aLedPin,VL);  // lights led
79     analogWrite(aBuzPin,VL);  // beeps buz
80    //Serial.print(roundOneDec(mTesla));
81     //Serial.println("mT");
82  } else {
83    Gauss=0;
84    mTesla=0;
85     analogWrite(aLedPin,0);  // off led
86    analogWrite(aBuzPin,0);  // off buz
87   }
88  display.clearDisplay();  // output to display
89  display.setTextColor(SSD1306_WHITE);
90   display.setTextSize(1);
91  display.setCursor(1,1);
92  display.print("Magnetic   Field Meter");
93  display.setTextSize(2);
94  display.setCursor(8,16);
95  mT="       "+String(roundOneDec(mTesla),1)+" mT";
96  display.print(mT.substring(mT.length()-9));   // right alignment
97  display.display();  
98  
99  fprevMillis=millis();
100   fTot=0;
101  fNr=0;
102  fMin=0;
103  fMax=0;
104}  //showVal()
105
106float roundOneDec(float   f) {
107  float y, d;
108  y = f*10;
109  d = y - (int)y;
110  y = (float)(int)(f*10)/10;
111   if (d >= 0.5) {
112    y += 0.1;
113   } else {
114    if (d < -0.5) {
115    y   -= 0.1;
116  }
117  }
118  return y;
119}  //roundOneDec()
120

/*
 This sketch acts as a Magnetic Field Meter, by Marco Zonca, 3/2021
   Arduino Nano as 5V MPU, UGN3503UA magnetic sensor, i2c Oled 128x32 display, a LED,
   one button, an active buzzer and a few resistors;

 Magnetic Field Meter,   output in milliTesla (mT)
  
 from sensor +- 1.3 mV = +- 1 Gauss = +- 0.1   mT
 from sensor 2.5V = 0 (0-2.5V = -2500 to 0 mV, 2.5-5V = 0 to 2500mV)  
*/

#include   <Wire.h>
#include <Adafruit_SSD1306.h>

Adafruit_SSD1306 display = Adafruit_SSD1306   (128, 32, &Wire, -1);

float aVal=0;
float aZero=0;
float aRead=0;
float   VL=0;
float Gauss=0;
float mTesla=0;
float fTot=0;
float fNr=0;
float   fMax=0;
float fMin=0;
float fAvr=0;

unsigned long fprevMillis=0;

const   unsigned long fMillis=500;  // update display and average calc every 0.5 seconds
const   int aValPin=14;
const int aLedPin=10;
const int aBuzPin=9;
const int aButton=15;

String   mT = "  -0.0 mT";

void setup() {
  //Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC,   0x3C); // Display Address 0x3C for 128x32 pixels
  mT.reserve(20);
}  //setup()

void   loop() {
  aRead=analogRead(aValPin);
  if (aZero==0) aZero=aRead;  // initial   auto zero
  if (digitalRead(aButton)==LOW) aZero=aRead;  // forced zero with   button
  aVal=(map(aRead,0,1023,0,5000)-map(aZero,0,1023,0,5000)) / 1.3;  //   to milliVolt, to Gauss
  if (aVal != 0) {
    fTot=fTot+aVal;
    fNr=fNr+1;
   }
  if (aVal>fMax) fMax=aVal;  // mem max
  if (aVal<fMin) fMin=aVal;  //   mem min
  if (millis() > (fMillis+fprevMillis)) showVal(); 
}  //loop()

void   showVal() {
  if (fMax != 0) {
    fTot=fTot-fMax;  // average without max
     fNr=fNr-1;    
  }
  if (fMin != 0) {
    fTot=fTot-fMin;  // average   without min
    fNr=fNr-1;    
  }
  if (fNr > 0) {
    aVal=fTot/fNr;   // average value
  } else {
    aVal=0;
  }
  if (aVal != aZero) {
     Gauss=aVal;
    mTesla=Gauss/10;  // to milliTesla
    VL=abs((aVal) /   10);
    if (VL>255) VL=255;
    analogWrite(aLedPin,VL);  // lights led
     analogWrite(aBuzPin,VL);  // beeps buz
    //Serial.print(roundOneDec(mTesla));
     //Serial.println("mT");
  } else {
    Gauss=0;
    mTesla=0;
     analogWrite(aLedPin,0);  // off led
    analogWrite(aBuzPin,0);  // off buz
   }
  display.clearDisplay();  // output to display
  display.setTextColor(SSD1306_WHITE);
   display.setTextSize(1);
  display.setCursor(1,1);
  display.print("Magnetic   Field Meter");
  display.setTextSize(2);
  display.setCursor(8,16);
  mT="       "+String(roundOneDec(mTesla),1)+" mT";
  display.print(mT.substring(mT.length()-9));   // right alignment
  display.display();  
  
  fprevMillis=millis();
   fTot=0;
  fNr=0;
  fMin=0;
  fMax=0;
}  //showVal()

float roundOneDec(float   f) {
  float y, d;
  y = f*10;
  d = y - (int)y;
  y = (float)(int)(f*10)/10;
   if (d >= 0.5) {
    y += 0.1;
   } else {
    if (d < -0.5) {
    y   -= 0.1;
  }
  }
  return y;
}  //roundOneDec()

Downloadable files

PCB bottom solder face