Calculate the correct current limit for driver A4988

Other Hardware Motors, Mechanics, Power and CNC
28

I got some different approaches but it would be nice to be able to get the ULN2003 to properly with just two pins.

I have wired this circuit and are trying with this code (problem: not precise. loosing position and jaggy in one direction)

const int coilA = 2;
const int coilB =  3;
const int ms = 2500;
const int ms1 = 0;
const int ms2 = 0;

int inc = 0;
bool changeDir = false;

void setup() {
  Serial.begin(9600);

  pinMode(coilA, OUTPUT);
  pinMode(coilB, OUTPUT);
  digitalWrite(coilA, LOW);
  digitalWrite(coilB, LOW);
}

void loop() {
  if (inc % 200 == 0) {
    changeDir = !changeDir;
    if (changeDir == 1) {
      Serial.println("CW");
    } else if (changeDir == 0) {
      Serial.println("CCW");
    }
    delay(10);
  }
  if (changeDir == 1) {
    cw();
  } else if (changeDir == 0) {
    ccw();
  }
  inc++;
}

void cw() {
  step1();
  step2();
  step3();
  step4();
}

void ccw() {
  step4();
  step3();
  step2();
  step1();
}

void step1 () {
  digitalWrite(coilA, LOW);
  digitalWrite(coilB, HIGH);
  delayMicroseconds(ms);
}

void step2 () {
  digitalWrite(coilA, HIGH);
  digitalWrite(coilB, HIGH);
  delayMicroseconds(ms);
}

void step3 () {
  digitalWrite(coilA, HIGH);
  digitalWrite(coilB, LOW);
  delayMicroseconds(ms);
}

void step4 () {
  digitalWrite(coilA, LOW);
  digitalWrite(coilB, LOW);
  delayMicroseconds(ms);
}

and with stepper library (that one wont turn in both directions)

#include <Stepper.h>

const int stepsPerRevolution = 32;  // change this to fit the number of steps per revolution
const int stepperSpeed = 60;
// for your motor

// initialize the stepper library on pins 8 through 11:
Stepper myStepper(stepsPerRevolution, 2, 3);

void setup() {
  // set the speed at 60 rpm:
  myStepper.setSpeed(stepperSpeed);
  // initialize the serial port:
  Serial.begin(9600);
}

void loop() {
  // step one revolution  in one direction:
  Serial.println("clockwise");
  myStepper.step(stepsPerRevolution);
  delay(500);

  // step one revolution in the other direction:
  Serial.println("counterclockwise");
  myStepper.step(-stepsPerRevolution);
  delay(500);
}