/*
  This sketch handle stepper motors without driver nor librairies.
  It was designed so that current does not flow through the coils
  when the motor is stopped.

  A Red LED lit reveals the current flow through a coil.
  A Green LED lit indicates the state of a line.

  The VLWS (Voltage Level When Stopped) is to keep the lines HIGH
  or LOW when stopped. In no case current flows through the coils.

  Cable colors as seen at: https://i.imgur.com/eZdhbHZ.png

  Written in 2024 by raphik
*/

#define AN 11
#define AP 10
#define BP  9
#define BN  8
#define VLWS LOW   // or HIGH if you find it more interesting

// https://blog.ars-electronica.com.ar/2015/04/tutorial-stepper-motor-paso-a-paso.html
//uint8_t sequence[4] = { B1000, B0010, B0100, B0001 };  // weaker torque
uint8_t sequence[4] = { B1010, B0110, B0101, B1001 };  // stronger torque

int8_t index = 0;

void setup() {
  Serial.begin(9600);
  pinMode(AN,OUTPUT);  pinMode(AP,OUTPUT);    // coil A
  pinMode(BP,OUTPUT);  pinMode(BN,OUTPUT);    // coil B
}

void loop() {
  int thinkanumber = random(100, 500 );
  Serial.println(thinkanumber);
  // sequence of movements that always ends in zero steps
  step(thinkanumber/5);  delay(500);
  step(-thinkanumber/3); delay(500);
  step(thinkanumber/5);  delay(500);
  step(thinkanumber%5);  delay(500);
  step(thinkanumber/5);  delay(500);
  step(-thinkanumber/3); delay(500);
  step(-thinkanumber%3); delay(500);
  step(thinkanumber/5);  delay(500);
  step(-thinkanumber/3); delay(500);
  step(thinkanumber/5);  delay(500);
  Serial.println(F("The stepper must've gotten back to zero."));
  delay(2000);
}

void step(int16_t steps) {
  int8_t direction = 0;
  if (steps > 0 ) direction = 1;
  if (steps < 0 ) direction = -1;
  for ( int16_t i = abs(steps); i > 0; i-- ) {
    index += direction;
    if (index == 4) index = 0;
    if (index == -1) index = 3;
    digitalWrite(AN, bitRead(sequence[index], 0));
    digitalWrite(AP, bitRead(sequence[index], 1));
    digitalWrite(BP, bitRead(sequence[index], 2));
    digitalWrite(BN, bitRead(sequence[index], 3));
    delay(20);
  }
  digitalWrite(AN, VLWS); digitalWrite(AP, VLWS);
  digitalWrite(BP, VLWS); digitalWrite(BN, VLWS);
}