Long story short I am attempting to slightly modify an existing sketch to add in a stepper motor function. I am reasonably new to arduino coding, and this sketch I am messing with is way above my skill level. This sketch operates a homemade metal detector, and I want to add in a section that will energize a stepper motor upon the metal detector reaching a certain threshold. While operating the metal detector there are a couple variables in the serial monitor that correlate to the strength of feedback from the metal detector, but I cannot for the life of me figure out what those values represent in the sketch itself. My other idea was to trigger the stepper motor off of an LED cycle instead, as the onboard LED of my R3 uno flashes every time the buzzer in my circuit "clicks". But I am at a loss as to which values I should tie an "if" statement to in order to energize the stepper when necessary. This was a bit long-winded, but I tried to articulate my problem the best I could. A solid ~75% of this sketch is greek to me so im working with the limited knowledge I have. I have identified and initialized the stepper in the sketch, but am at a loss as to how to actually tie its function into this sketch. See attached sketch. Thank you in advance.
//Metal detector based on pulse delay in LR circuit
//Connect a coil beween pin 10 and pin 8,
//a 100 Ohm resistor between pin 8 and ground,
//a speaker in series with a 10muF capacitor between pin 12 and ground,
//a reset-button between A0 and ground.
//Reference coil: 60 turns, diameter 6cm, AWG26 (0.4mm) wire. L~300muH, R~2Ohm
//
//R. Oldeman Oct 11 2020, CC BY-NC-SA 4.0 licence
#define debug true
//some parameters
#define sensitivity 5000 //threshold as a fraction of reference
#define aimtime 160000 //aim for measurement every 160k cycles (=10ms)
#define LEDpulselen 16000 //length of the LED pulse in clock cycles
#define cycles 40 //number of clock cycles reserved for calculations
#define printfrac 50 //fraction of measurements printed when in debug mode
//pin definitions - cannot change freely!
#define pulsepin 10 //must be pin 10 - TIMER1B output
#define probepin 8 //must be pin 8 - input capture pin
#define LEDpin 13 //if changed also need to update the direct-port writing
#define soundpin 12 //if changed also need to update the direct-port writing
#define resetpin A0 //can be changed freely
//global variables - shared between main loop and measurement function
long int imeas = 0; //counts the number of measurements performed
int absdiff; //absolute value of difference wrt reference
long int phase = 0; //tracks integral of absdiff
long int phasemax; //value at which the phase counter turns over
int LEDcycles = 0; //number of cycles that the LED pin stays high
int LEDcycle = 0; //cycle index of the LED pulse
//
#include <Stepper.h>
const int stepsPerRevolution = 2048; // number of steps per revolution
Stepper myStepper(32, 2, 4, 3, 5); // initialize stepper on pins 2 through 5
//
void setup() {
noInterrupts(); //disable all inerrupts to avoid glitches
if (debug)Serial.begin(9600);
pinMode(pulsepin, OUTPUT);
digitalWrite(pulsepin, LOW);
pinMode(probepin, INPUT);
pinMode(LEDpin, OUTPUT);
digitalWrite(LEDpin, LOW);
pinMode(soundpin, OUTPUT);
digitalWrite(soundpin, LOW);
pinMode(resetpin, INPUT_PULLUP);
//
myStepper.setSpeed(750); // set speed of motor to 750 rpm
//
//setup timer1 to FASTPWM on pin 10
TCCR1A = 0B00100011;
TCCR1B = 0B00011001;
}
//perform measurement of delay of the trailing edge
long int meas(int period, int minlen, int maxlen, int steplen, int nloop) {
long int sum = 0;
int nmiss = 0;
OCR1A = period; //set the period
TIFR1 |= 0B00000001; //clear the timer overflow bit
for (int iloop = 0; iloop < nloop; iloop++) {
for (int len = minlen; len < maxlen; len += steplen) {
OCR1B = len; //set the pulselength
while ((TIFR1 & 0B00000001) == 0); //wait for timer overflow
TIFR1 |= 0B00000001; //clear the timer overflow bit
while (TCNT1 < (period - cycles)); //wait till pulse is almost finished
if ( (TIFR1 & 0B00100000) != 0) { //check if trailing edge has been detected
sum += (ICR1 - len);
TIFR1 |= 0B00100000; //clear the input capture flag
} else {
nmiss++;
}
//update phase
phase += absdiff;
//blink and click when phase rolls through
if (phase > phasemax) {
phase -= phasemax;
LEDcycle = LEDcycles;
PORTB = (PORTB | 0B00100000); //switch on LED
PORTB = (PORTB ^ 0B00010000); //invert sound pin - click!
}
//switch off LED when it's been on long enough
if (LEDcycle > 0) {
LEDcycle--;
if (LEDcycle == 0)PORTB = (PORTB & (!0B00100000));
}
}
}
if (nmiss > 0)sum = 0; //invalidate the result if there have been missing pulses
return sum;
}
//flash LED with error code indefinitely if there's been an error
void go_error(byte errorcode) {
if (debug) {
Serial.print("ERROR ");
Serial.print(errorcode);
if (errorcode == 1)Serial.println(": No pulse on probe pin - check connections");
if (errorcode == 2)Serial.println(": Delay too short - try more windings");
if (errorcode == 3)Serial.println(": Delay too long - try fewer windings");
if (errorcode == 4)Serial.println(": No robust pulse on pulselength scan - check coil resistance");
}
//enable in interrupts to use delay() and flash to indicate error code
interrupts();
while (true) {
for (byte i = 0; i < errorcode; i++) {
digitalWrite(LEDpin, HIGH);
delay(100);
digitalWrite(LEDpin, LOW);
delay(100);
}
delay(500);
}
}
void loop() {
//perform initial robust measurement of average delay time
long int tau = meas(16000, 8000, 8001, 1, 16) / 16;
if (debug)Serial.print("delay in clock cycles:");
if (debug)Serial.println(tau);
if (debug)Serial.print("estimated coil inductance in muH:");
if (debug)Serial.println(1.44 * tau * 100.0 / (16.0));
if (tau == 0) go_error(1); // no pulse
if (tau < 5) go_error(2); // too short
if (tau > 800)go_error(3); // too long
//choose pulsing parmeters based on measured delay time
int minlen = 3 * tau;
int maxlen = 5 * tau;
int period = maxlen + 2 * tau + cycles;
LEDcycles = LEDpulselen / period + 1;
// repeat loop or speed up loop to approach aimed duration of measurement
int steplen = 1;
int nloop = 1;
float tottime = float(period) * (maxlen - minlen);
if (tottime > aimtime * (3.0 / 2.0)) steplen = round(tottime / aimtime);
if (tottime < aimtime * (2.0 / 3.0)) nloop = round(aimtime / tottime);
if (debug)Serial.print(" minlen: ");
if (debug)Serial.print(minlen);
if (debug)Serial.print(" maxlen: ");
if (debug)Serial.print(maxlen);
if (debug)Serial.print(" steplen: ");
if (debug)Serial.print(steplen);
if (debug)Serial.print(" period: ");
if (debug)Serial.print(period);
if (debug)Serial.print(" nloop: ");
if (debug)Serial.print(nloop);
if (debug)Serial.print(" LEDcycles: ");
if (debug)Serial.println(LEDcycles);
//perform a scan from minlen to maxlen
long int minval = 1000000000;
for (int len = minlen; len < maxlen; len += steplen) {
long int val = meas(period, len, len + 1, 1, nloop);
minval = min(val, minval);
if (debug)Serial.print("len,val:");
if (debug)Serial.print(len);
if (debug)Serial.print(" ");
if (debug)Serial.println(val);
}
if (minval == 0)go_error(4);
//determine the reference value
long int ref = meas(period, minlen, maxlen, steplen, nloop);
//threshold and phasemax
int threshold = ref / sensitivity;
phasemax = 16000000 / period * threshold; //aim for 1Hz at threshold
if (debug)Serial.print("reference, threshold, phasemax: ");
if (debug)Serial.print(ref);
if (debug)Serial.print(" ");
if (debug)Serial.print(threshold);
if (debug)Serial.print(" ");
if (debug)Serial.println(phasemax);
long int sum = 0;
long int sumsq = 0;
while (true) {
long int val = meas(period, minlen, maxlen, steplen, nloop);
//check if reset of reference value is requested
if (digitalRead(resetpin) == LOW) ref = val;
int diff = val - ref;
absdiff = abs(diff);
if (absdiff < threshold) {
phase = 0; //reset the phase
if (diff > 0)ref += 1; //absorb slow drifts
if (diff < 0)ref -= 1;
}
if (debug) {
sum += diff;
sumsq += long(diff) * long(diff);
if (imeas % printfrac == 0) {
float mean = float(sum) / printfrac;
float rms = sqrt( (float(sumsq) / printfrac) - pow(mean, 2.0) );
Serial.print(imeas);
Serial.print(" val ref diff phase ");
Serial.print(val);
Serial.print(" ");
Serial.print(ref);
Serial.print(" ");
Serial.print(diff);
Serial.print(" ");
Serial.print(mean);
Serial.print(" ");
Serial.print(rms);
Serial.println("");
sum = 0; sumsq = 0;
}
}
imeas++;
}
}
