Stepper Motor and ULN2003 Driver Board on Raspberry Pi with Node.js

ULN2003StepperMotor.js

// Inspired from:
// https://ben.akrin.com/driving-a-28byj-48-stepper-motor-uln2003-driver-with-a-raspberry-pi/
// https://gist.github.com/wolli2710/9ae48c9f39737896c1f6
const { Gpio } = require("onoff");

const in1ToGpio = 17; // IN1
const in2ToGpio = 18; // IN2
const in3ToGpio = 27; // IN3
const in4ToGpio = 22; // IN4
const timeout = 1; // milliseconds
const antiClockWise = false;

const gpios = [
  new Gpio(in1ToGpio, "out"),
  new Gpio(in2ToGpio, "out"),
  new Gpio(in3ToGpio, "out"),
  new Gpio(in4ToGpio, "out")
];

// Make sure to clean up GPIO on exit
let processStepTimeoutID;
function exit() {
  clearTimeout(processStepTimeoutID);
  gpios.forEach(gpio => gpio.writeSync(0));
  process.exit(0);
}
process.on("SIGINT", exit); // CTRL+C
process.on("SIGQUIT", exit); // Keyboard quit
process.on("SIGTERM", exit); // `kill` command

// http://www.4tronix.co.uk/arduino/Stepper-Motors.php
// From the specification:
// - Reduction ratio: 1/64
// - Step angle: 5.625 x 1/64
// This gives 4096 steps to get a full 360° (5.625 x 1/64 per step)
const sequenceSteps = [
  [1, 0, 0, 0],
  [1, 1, 0, 0],
  [0, 1, 0, 0],
  [0, 1, 1, 0],
  [0, 0, 1, 0],
  [0, 0, 1, 1],
  [0, 0, 0, 1],
  [1, 0, 0, 1]
];

// For anti-clockwise motion, simply follow the sequence in reverse
if (antiClockWise) {
  sequenceSteps.reverse();
}

const lastStepIndex = sequenceSteps.length - 1;
let currentStepIndex = 0;
function processStep () {
  const step = sequenceSteps[currentStepIndex];
  Promise.resolve([
    gpios[0].write(step[0]),
    gpios[1].write(step[1]),
    gpios[2].write(step[2]),
    gpios[3].write(step[3])
  ]).then(() => {
    currentStepIndex = currentStepIndex < lastStepIndex ? currentStepIndex + 1 : 0;
    processStepTimeoutID = setTimeout(processStep, timeout);
  });
}
processStep();