Remote stepper on an Arduino Uno

// Remote stepper: VOL+ and VOL- on the IR remote turn a stepper motor.
//
//   IR receiver   OUT -> pin 12, GND -> GND, VCC -> 5V
//   ULN2003 board IN1 -> pin 8, IN2 -> pin 9, IN3 -> pin 10, IN4 -> pin 11
//                 + -> 5V, - -> GND
//
// Each press of VOL+ turns the shaft a quarter turn clockwise, and VOL- a
// quarter turn back. The 28BYJ-48 takes 2048 full steps for one turn of its
// output shaft, so a quarter turn is 512 steps.
//
// The Stepper library wants the pins as IN1, IN3, IN2, IN4: that is why the
// constructor below says 8, 10, 9, 11. Given 8, 9, 10, 11 the motor hums and
// does not turn.

#include <IRremote.hpp>
#include <Stepper.h>

const int RECEIVER_PIN = 12;
const int STEPS_PER_TURN = 2048;
const int QUARTER = STEPS_PER_TURN / 4;

Stepper motor(STEPS_PER_TURN, 8, 10, 9, 11);

void release() {
  // Let the coils go between moves, so the driver stays cool.
  for (int pin = 8; pin <= 11; pin++) digitalWrite(pin, LOW);
}

void setup() {
  Serial.begin(9600);
  IrReceiver.begin(RECEIVER_PIN, ENABLE_LED_FEEDBACK);
  motor.setSpeed(15);
  Serial.println("Mokxi Uno: remote stepper. VOL+ and VOL- turn the shaft.");
}

void loop() {
  if (!IrReceiver.decode()) return;
  bool repeat = IrReceiver.decodedIRData.flags & IRDATA_FLAGS_IS_REPEAT;
  uint8_t command = IrReceiver.decodedIRData.command;
  IrReceiver.resume();
  if (repeat) return;
  if (command == 0x15) {
    Serial.println("VOL+: a quarter turn clockwise");
    motor.step(QUARTER);
    release();
  } else if (command == 0x07) {
    Serial.println("VOL-: a quarter turn back");
    motor.step(-QUARTER);
    release();
  } else {
    Serial.print("button 0x");
    Serial.print(command, HEX);
    Serial.println(" does nothing here");
  }
}