//  Sketch by R. Jordan Kreindler, written October 2016, to rotate
//    a stepper motor using the Half Step Method and reverse direction
//    after approximately a full revolution. A 48 basic step stepper
//    motor is used, yielding 96 steps for the half step method.
//  An LCD is used to show rotation direction, angle(s), and RPM.

float RPM;
unsigned long time;

#include <LiquidCrystal.h>
// LiquidCrystal (RS,  E, d4, d5, d6, d7)
LiquidCrystal lcd(13, 12, 11, 10,  9,  8); // A standalone, non-shield, LCD
//    was used.
// Pin assignments
int aPin      = 4; //IN1: coil a one end
int bPin      = 3; //IN2: coil b one end
int aPrimePin = 5; //IN3: coil aPrime other end of coil a
int bPrimePin = 2; //IN4: coil bPrime other end of coil b
// We do not connect IN5, IN6, or IN7

int one   = aPin;
int two   = bPin;
int three = aPrimePin;
int four  = bPrimePin;

int degrees = 0;

int delay1 = 20;   // The delay between each step in milliseconds
int delay2 = 50;   // The delay after each full revolution, in milliseconds
int count  = 0;    // The number of steps

int numberOfRotations = 1; // The number of times the rotor has
//   turned 360 degrees.

void setup() {
  // Set all pins as output to send output signals from the Arduino
  //   UNO to the coil windings of the stator
  lcd.begin(16, 2); // Sets the size of the LCD in characters and lines
  lcd.clear();     // Clear the LCD screen of characters and symbols
  pinMode(aPin,      OUTPUT);
  pinMode(bPin,      OUTPUT);
  pinMode(aPrimePin, OUTPUT);
  pinMode(bPrimePin, OUTPUT);
  lcd.setCursor(0, 0);
  lcd.print("   Clockwise");

  // Start with all coils off
  digitalWrite(aPin,      LOW);
  digitalWrite(bPin,      LOW);
  digitalWrite(aPrimePin, LOW);
  digitalWrite(bPrimePin, LOW);
}

void loop() {

  // Send current to
  // 1. The aPin
  // 2. The aPin, and the bPin
  // 3. The bPin
  // 4. Then to the bPin and the aPrimePin
  // 5. Then to the aPrimePin
  // 6. Then to the aPrimePin and the bPrime Pin
  // 7. Then to the bPrimePin
  // 8. Then the bPrimePin and the aPin.
  // Thus producing steps using the half step method

  // 1. Set the aPin High
  digitalWrite(aPin,      HIGH);
  digitalWrite(bPin,      LOW);
  digitalWrite(aPrimePin, LOW);
  digitalWrite(bPrimePin, LOW);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  // 2. Energize aPin and bPin to HIGH
  digitalWrite(aPin,      HIGH);
  digitalWrite(bPin,      HIGH);
  digitalWrite(aPrimePin, LOW);
  digitalWrite(bPrimePin, LOW);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  // 3. Set the bPin to High
  digitalWrite(aPin,      LOW);
  digitalWrite(bPin,      HIGH);
  digitalWrite(aPrimePin, LOW);
  digitalWrite(bPrimePin, LOW);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  // 4. Set the bPin and the aPrimePin to HIGH
  digitalWrite(aPin,      LOW);
  digitalWrite(bPin,      HIGH);
  digitalWrite(aPrimePin, HIGH);
  digitalWrite(bPrimePin, LOW);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  //  5. Set the aPrime Pin to high
  digitalWrite(aPin,      LOW);
  digitalWrite(bPin,      LOW);
  digitalWrite(aPrimePin, HIGH);
  digitalWrite(bPrimePin, LOW);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  // 6. Set the aPrimePin and the bPrime Pin to HIGH
  digitalWrite(aPin,      LOW);
  digitalWrite(bPin,      LOW);
  digitalWrite(aPrimePin, HIGH);
  digitalWrite(bPrimePin, HIGH);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  // 7. Set the bPrimePin to HIGH
  digitalWrite(aPin,      LOW);
  digitalWrite(bPin,      LOW);
  digitalWrite(aPrimePin, LOW);
  digitalWrite(bPrimePin, HIGH);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  // 8. Set the bPrimePin and the aPin to HIGH
  digitalWrite(aPin,      HIGH);
  digitalWrite(bPin,      LOW);
  digitalWrite(aPrimePin, LOW);
  digitalWrite(bPrimePin, HIGH);
  // Allow some delay between energizing the coils to allow
  //  the stepper rotor time to respond.
  delay(delay1); // So, delay1 milliseconds

  count = count + 8;
  degrees = (360.0 * (count / 400.0));

  if ((numberOfRotations % 2) == 1) { // Check if number of rotations is even
    lcd.setCursor(0, 0);      // Move the cursor to 1th position on 1st line
    lcd.print("   Clockwise    ");
    lcd.setCursor(0, 1);      // Move the cursor to 1th position on 2nd line
    lcd.print("  ");          // Print a space
    lcd.print(degrees);       // Print angular position in degrees
    lcd.print((char)223);     // Print degree symbol
    lcd.print(" ");           // Print a space
  }
  else { // If numberOfRotations is odd number
    lcd.setCursor(0, 0);      // Move the cursor to 1th position on 1st line
    lcd.print(" Anti-Clockwise  ");
    degrees = 360 - degrees;
    lcd.setCursor(0, 1);      // Move the cursor to 1th position on 2nd line
    lcd.print(" -");          // Print a minus sign
    lcd.print(degrees);       // Print angular position in degrees
    lcd.print((char)223);     // Print degree symbol
    lcd.print(" ");           // Print a space
  }
  if (count == 96) { // A full revolution of the stepper
    numberOfRotations = ++numberOfRotations;
    time = millis();
    RPM = time / numberOfRotations; // Average time of a rotation
    RPM = (60000.00 / RPM); // Number of rotations per minute
    if (numberOfRotations >= 10) {
      lcd.setCursor(7, 1);
      lcd.print("RPM:");
      lcd.print(round(RPM)); //Print RPM as integer
      lcd.print("       ");
    }
    delay(delay2); // delay2/1000 second(s) after each full rotation
    count = 0; // Reset step counter to zero
    //Reversive direction after each turn
    if ((numberOfRotations) % 2 == 0) { // Check if number of rotations is even
      //   if so reverse direction
      aPin      = four;
      bPin      = three;
      aPrimePin = two;
      bPrimePin = one;
    }
    else {  // If number of rotations is an odd number
      aPin      = one;
      bPin      = two;
      aPrimePin = three;
      bPrimePin = four;
    }
  }
}