FlProg

Arduino
// Induction balance metal detector

// We run the CPU at 16MHz and the ADC clock at 1MHz (АЦП работает на 1 МГц). ADC resolution is reduced to 8 bits at this speed. (разрешение АЦП уменьшено до 8 бит)

// Timer 1 is used to divide the system clock by about 256 to produce a 62.5kHz square wave. (Таймер 1 использовается для формирования прямоугольных импульсов с частотой 62,5 кГц)
// This is used to drive timer 0 and also to trigger ADC conversions.
// Timer 0 is used to divide the output of timer 1 by 8, giving a 7.8125kHz signal for driving the transmit coil.
// Таймер 0 делит выход таймера 1 на 8, и, таким образом, формирует сигнал частотой 7.8125kHz для управления передающей катушкой
// This gives us 16 ADC clock cycles for each ADC conversion (it actually takes 13.5 cycles), and we take 8 samples per cycle of the coil drive voltage.
// The ADC implements four phase-sensitive detectors at 45 degree intervals. Using 4 instead of just 2 allows us to cancel the third harmonic of the
// coil frequency.

// Timer 2 will be used to generate a tone for the earpiece or headset. (таймер 2 используется для генерации тона для наушников)

// Other division ratios for timer 1 are possible, from about 235 upwards.

// Wiring:
// Connect digital pin 4 (alias T0) to digital pin 9
// Connect digital pin 5 through resistor to primary coil and tuning capacitor
// Connect output from receive amplifier to analog pin 0. Output of receive amplifier should be biased to about half of the analog reference.
// When using USB power, change analog reference to the 3.3V pin, because there is too much noise on the +5V rail to get good sensitivity.
#include <LiquidCrystal.h>
#include <LcdBarGraph.h>
#define max_ampAverage 200
LiquidCrystal lcd(6, 7, 10, 11, 12, 13);
LcdBarGraph lbg(&lcd, 16, 0, 1);

#define TIMER1_TOP (259) // can adjust this to fine-tune the frequency to get the coil tuned (see above) (это значение используется для точной настройки частоты катушки)

#define USE_3V3_AREF (1) // set to 1 of running on an Arduino with USB power, 0 for an embedded atmega28p with no 3.3V supply available

// Digital pin definitions
// Digital pin 0 not used, however if we are using the serial port for debugging then it's serial input
const int debugTxPin = 1; // transmit pin reserved for debugging (передающий контакт, зарезервированный для целей отладки)
const int encoderButtonPin = 2; // encoder button, also IN0 for waking up from sleep mode
const int earpiecePin = 3; // earpiece, aka OCR2B for tone generation
const int T0InputPin = 4;
const int coilDrivePin = 5;
const int LcdRsPin = 6;
const int LcdEnPin = 7;
const int LcdPowerPin = 8; // LCD power and backlight enable
const int T0OutputPin = 9;
const int lcdD4Pin = 10;
const int lcdD5Pin = 11; // pins 11-13 also used for ICSP
const int LcdD6Pin = 12;
const int LcdD7Pin = 13;

// Analog pin definitions (используемые аналоговые контакты)
const int receiverInputPin = 0;
const int encoderAPin = A1;
const int encoderBpin = A2;
// Analog pins 3-5 not used

// Variables used only by the ISR
int16_t bins[4]; // bins used to accumulate ADC readings, one for each of the 4 phases (используются для хранения значений, считываемых с АЦП)
uint16_t numSamples = 0;
const uint16_t numSamplesToAverage = 1024;

// Variables used by the ISR and outside it
volatile int16_t averages[4]; // when we've accumulated enough readings in the bins, the ISR copies them to here and starts again
volatile uint32_t ticks = 0; // system tick counter for timekeeping
volatile bool sampleReady = false; // indicates that the averages array has been updated

// Variables used only outside the ISR
int16_t calib[4]; // values (set during calibration) that we subtract from the averages (значения, устанавливаемые во время калибровки, в дальнейшем мы их вычитаем из средних значений)

volatile uint8_t lastctr;
volatile uint16_t misses = 0; // this counts how many times the ISR has been executed too late. Should remain at zero if everything is working properly.

const double halfRoot2 = sqrt(0.5);
const double quarterPi = 3.1415927/4.0;
const double radiansToDegrees = 180.0/3.1415927;

// The ADC sample and hold occurs 2 ADC clocks (= 32 system clocks) after the timer 1 overflow flag is set.
// This introduces a slight phase error, which we adjust for in the calculations.
const float phaseAdjust = (45.0 * 32.0)/(float)(TIMER1_TOP + 1);

float threshold = 5.0; // lower = greater sensitivity. 10 is just about usable with a well-balanced coil.
// The user will be able to adjust this via a pot or rotary encoder. (эту границу можно сделать настраиваемой с помощью потенциометра или энкодера)

void setup()
{
lcd.begin(16, 2);// LCD 16X2
pinMode(encoderButtonPin, INPUT_PULLUP);
digitalWrite(T0OutputPin, LOW);
pinMode(T0OutputPin, OUTPUT); // pulse pin from timer 1 used to feed timer 0
digitalWrite(coilDrivePin, LOW);
pinMode(coilDrivePin, OUTPUT); // timer 0 output, square wave to drive transmit coil

cli();
// Stop timer 0 which was set up by the Arduino core
TCCR0B = 0; // stop the timer
TIMSK0 = 0; // disable interrupt
TIFR0 = 0x07; // clear any pending interrupt

// Set up ADC to trigger and read channel 0 on timer 1 overflow
#if USE_3V3_AREF
ADMUX = (1 << ADLAR); // use AREF pin (connected to 3.3V) as voltage reference, read pin A0, left-adjust result
#else
ADMUX = (1 << REFS0) | (1 << ADLAR); // use Avcc as voltage reference, read pin A0, left-adjust result
#endif
ADCSRB = (1 << ADTS2) | (1 << ADTS1); // auto-trigger ADC on timer/counter 1 overflow
ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) | (1 << ADPS2); // enable adc, enable auto-trigger, prescaler = 16 (1MHz ADC clock)
DIDR0 = 1;

// Set up timer 1.
// Prescaler = 1, phase correct PWM mode, TOP = ICR1A
TCCR1A = (1 << COM1A1) | (1 << WGM11);
TCCR1B = (1 << WGM12) | (1 << WGM13) | (1 << CS10); // CTC mode, prescaler = 1
TCCR1C = 0;
OCR1AH = (TIMER1_TOP/2 >> 8);
OCR1AL = (TIMER1_TOP/2 & 0xFF);
ICR1H = (TIMER1_TOP >> 8);
ICR1L = (TIMER1_TOP & 0xFF);
TCNT1H = 0;
TCNT1L = 0;
TIFR1 = 0x07; // clear any pending interrupt
TIMSK1 = (1 << TOIE1);

// Set up timer 0
// Clock source = T0, fast PWM mode, TOP (OCR0A) = 7, PWM output on OC0B
TCCR0A = (1 << COM0B1) | (1 << WGM01) | (1 << WGM00);
TCCR0B = (1 << CS00) | (1 << CS01) | (1 << CS02) | (1 << WGM02);
OCR0A = 7;
OCR0B = 3;
TCNT0 = 0;
sei();

while (!sampleReady) {} // discard the first sample (отбрасываем первый отсчет)
misses = 0;
sampleReady = false;

Serial.begin(19200);
}

// Timer 0 overflow interrupt (прерывание от таймера 0). This serves 2 purposes: (служит для 2-х целей)
// 1. It clears the timer 0 overflow flag. If we don't do this, the ADC will not see any more Timer 0 overflows and we will not get any more conversions.
// 2. It increments the tick counter, allowing is to do timekeeping. We get 62500 ticks/second.
// We now read the ADC in the timer interrupt routine instead of having a separate comversion complete interrupt.
ISR(TIMER1_OVF_vect)
{
++ticks;
uint8_t ctr = TCNT0;
int16_t val = (int16_t)(uint16_t)ADCH; // only need to read most significant 8 bits (нам нужно считывать только 8 наиболее значащих бит)
if (ctr != ((lastctr + 1) & 7))
{
++misses;
}
lastctr = ctr;
int16_t *p = &bins[ctr & 3];
if (ctr < 4)
{
*p += (val);
if (*p > 15000) *p = 15000;
}
else
{
*p -= val;
if (*p < -15000) *p = -15000;
}
if (ctr == 7)
{
++numSamples;
if (numSamples == numSamplesToAverage)
{
numSamples = 0;
if (!sampleReady) // if previous sample has been consumed
{
memcpy((void*)averages, bins, sizeof(averages));
sampleReady = true;
}
memset(bins, 0, sizeof(bins));
}
}
}

void loop()
{
while (!sampleReady) {}
uint32_t oldTicks = ticks;

if (digitalRead(encoderButtonPin) == LOW)
{
// Calibrate button pressed. We save the current phase detector outputs and subtract them from future results.
// This lets us use the detector if the coil is slightly off-balance.
// It would be better to everage several samples instead of taking just one.
for (int i = 0; i < 4; ++i)
{
calib = averages;
}
sampleReady = false;
Serial.print("Calibrated: ");

lcd.setCursor(0,0);
lcd.print("Calibrating... ");
for (int i = 0; i < 4; ++i)
{
Serial.write(' ');

Serial.print(calib);

lcd.setCursor(0,1);
lcd.print(' ');
lcd.print(calib[4]);
lcd.print(" ");
}
Serial.println();
}
else
{
for (int i = 0; i < 4; ++i)
{
averages -= calib;
}
const double f = 200.0;

// Massage the results to eliminate sensitivity to the 3rd harmonic, and divide by 200
double bin0 = (averages[0] + halfRoot2 * (averages[1] - averages[3]))/f;
double bin1 = (averages[1] + halfRoot2 * (averages[0] + averages[2]))/f;
double bin2 = (averages[2] + halfRoot2 * (averages[1] + averages[3]))/f;
double bin3 = (averages[3] + halfRoot2 * (averages[2] - averages[0]))/f;
sampleReady = false; // we've finished reading the averages, so the ISR is free to overwrite them again

double amp1 = sqrt((bin0 * bin0) + (bin2 * bin2));
double amp2 = sqrt((bin1 * bin1) + (bin3 * bin3));
double ampAverage = (amp1 + amp2)/2.0;

// The ADC sample/hold takes place 2 clocks after the timer overflow
double phase1 = atan2(bin0, bin2) * radiansToDegrees + 45.0;
double phase2 = atan2(bin1, bin3) * radiansToDegrees;

if (phase1 > phase2)
{
double temp = phase1;
phase1 = phase2;
phase2 = temp;
}

double phaseAverage = ((phase1 + phase2)/2.0) - phaseAdjust;
if (phase2 - phase1 > 180.0)
{
if (phaseAverage < 0.0)
{
phaseAverage += 180.0;
}
else
{
phaseAverage -= 180.0;
}
}

// For diagnostic purposes, print the individual bin counts and the 2 indepedently-calculated gains and phases
Serial.print(misses);
Serial.write(' ');

if (bin0 >= 0.0) Serial.write(' ');
Serial.print(bin0, 2);
Serial.write(' ');
if (bin1 >= 0.0) Serial.write(' ');
Serial.print(bin1, 2);
Serial.write(' ');
if (bin2 >= 0.0) Serial.write(' ');
Serial.print(bin2, 2);
Serial.write(' ');
if (bin3 >= 0.0) Serial.write(' ');
Serial.print(bin3, 2);
Serial.print(" ");
Serial.print(amp1, 2);
Serial.write(' ');
Serial.print(amp2, 2);
Serial.write(' ');
if (phase1 >= 0.0) Serial.write(' ');
Serial.print(phase1, 2);
Serial.write(' ');
if (phase2 >= 0.0) Serial.write(' ');
Serial.print(phase2, 2);
Serial.print(" ");

// Print the final amplitude and phase, which we use to decide what (if anything) we have found)
if (ampAverage >= 0.0) Serial.write(' ');
Serial.print(ampAverage, 1);
Serial.write(' ');

lcd.setCursor(0,0);
lcd.print(" ");
lcd.print(ampAverage);
lcd.setCursor(0,1);
lbg.drawValue(ampAverage, max_ampAverage);

if (phaseAverage >= 0.0) Serial.write(' ');
Serial.print((int)phaseAverage);

// Decide what we have found and tell the user
if (ampAverage >= threshold)
{
// When held in line with the centre of the coil:
// - non-ferrous metals give a negative phase shift, e.g. -90deg for thick copper or aluminium, a copper olive, -30deg for thin alumimium.
// Ferrous metals give zero phase shift or a small positive phase shift.
// So we'll say that anything with a phase shift below -20deg is non-ferrous.
if (phaseAverage < -20.0)
{
Serial.print(" Non-ferrous");
lcd.setCursor(0,0);
lcd.print("NonFerous ");

}
else
{
Serial.print(" Ferrous");
lcd.setCursor(0,0);
lcd.print("Ferrous ");
}
float temp = ampAverage;

int thisPitch = map (temp, 10, 200, 100, 1500);
tone(3, thisPitch,120);

while (temp > threshold)
{
Serial.write('!');
temp -= (threshold/2);
}
}
Serial.println();

}
while (ticks - oldTicks < 8000)
{
}
}