// Using a stepper to move an equilateral barn-door tracker at sidereal rate.
// Written by John Wasser, on May 23rd, 2020
// Copied from https://forum.arduino.cc/t/jjrobots-startracker/948662/3
//
// Wokwi Simulation: https://wokwi.com/projects/390541131703748609
// Modified to use this simulated hardware setup and add a speed adjustment potentiometer
// Second stepper is unused in this case

const uint16_t StepsPerRevolution = 200;
const float MillimetersPerRevolution  = 1.0; // 1mm pitch threaded rod
const uint16_t RotationRadiusMM = 400;  // Distance from hinge to threaded rod.

// connection Constants

// As in StepperDemo for Motor 1 on AVR
constexpr byte dirPinStepper  = 8;
constexpr byte enablePinStepper = 12;
constexpr byte stepPinStepper =  9;  // OC1A in case of AVR
constexpr byte dirPinStepper2  =  7;
constexpr byte enablePinStepper2 = 12;
constexpr byte stepPinStepper2 =  10;  // OC1B in case of AVR
constexpr byte PotPin = A0;


// Some sidereal rate constants:
// Seconds per Sidereal Day: 86164.0905  (Astronomical constant from Wikipedia)
// Radians per Second 7.2921158579e-5  (2 Pi radians divided by Siderail Day in Seconds)
const unsigned long MillisecondsPerRadian = 13713441;

uint32_t TimeAtLastStep = 0;
uint32_t IntervalToNextStep = 0;
uint32_t CurrentSteps = 0;  // Barn Door Tracker starts closed.
float CurrentAngle = 0;

void setup()
{
  Serial.begin(115200);

  TimeAtLastStep = millis();

  pinMode(stepPinStepper, OUTPUT);
  pinMode(dirPinStepper, OUTPUT);
}

void loop()
{
  uint32_t currentTime = millis();

  if (currentTime - TimeAtLastStep >= IntervalToNextStep)
  {
    TimeAtLastStep += IntervalToNextStep;


    // Code Here to Step Once
    digitalWrite(stepPinStepper, HIGH);
    //delay(1);
    digitalWrite(stepPinStepper, LOW);

    CurrentSteps++;

    uint32_t nextStep = CurrentSteps + 1;
    float nextRodLengthMM = (nextStep * MillimetersPerRevolution) / (float)StepsPerRevolution;

    float nextAngle = asin(nextRodLengthMM / (2 * RotationRadiusMM)) * 2.0;
    float deltaAngle = nextAngle - CurrentAngle;

    IntervalToNextStep = MillisecondsPerRadian * deltaAngle + speedAdjustment();
    CurrentAngle = nextAngle;

    Serial.print("ms:");
    Serial.print(currentTime);
    Serial.print("\tsteps:");
    Serial.print(CurrentSteps);
    Serial.print("\tIntervalMs:");
    Serial.println(IntervalToNextStep);
  }
}

int speedAdjustment(void) {
  // calculate a speed adjustment using a pot and a deadband
  const int DeadbandTop = 700;
  const int DeadbandBottom = 300;
  const int AdjustMax = 100;
  int potVal = analogRead(PotPin);
  int adjustment = 0;
  if (potVal >= DeadbandTop) {
    adjustment = map(potVal, DeadbandTop, 1023, 0, AdjustMax);
  }
  if (potVal <= DeadbandBottom) {
    adjustment = map(potVal, 0, DeadbandBottom, -AdjustMax, 0);
  }
  return (-adjustment); // change sign to flip sense of pot.
}