Summer fan: four buttons and an L293D (pins 9 and 10), on an Arduino Uno

// A summer fan: four buttons pick the speed of a motor on an L293D.
//
//   L293D 1,2EN -> 5V   VCC1 (16) and VCC2 (8) -> 5V   GND -> GND
//   L293D 1A -> pin 10   2A -> pin 9   1Y and 2Y -> the motor's two leads
//   buttons on pins 4, 5, 6 and 7, each to GND (internal pull-ups)
//
// A board pin cannot run a motor, so the L293D does it: each Y output copies
// its A input, with the motor's own current behind it. One input HIGH and the
// other LOW turns the motor; both LOW stops it. analogWrite on 1A, with 2A
// held LOW, chooses how fast.
//
// Press a button: pin 4 is off, 5 slow, 6 medium and 7 fast.

const int MOTOR_1A = 10;
const int MOTOR_2A = 9;
const int BUTTONS[4] = {4, 5, 6, 7};
const int SPEEDS[4] = {0, 120, 180, 255};
const char *NAMES[4] = {"off", "slow", "medium", "fast"};

void setup() {
  pinMode(MOTOR_1A, OUTPUT);
  pinMode(MOTOR_2A, OUTPUT);
  digitalWrite(MOTOR_2A, LOW);
  for (int i = 0; i < 4; i++) pinMode(BUTTONS[i], INPUT_PULLUP);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: fan buttons on 4 (off), 5, 6 and 7 (fast)");
}

void loop() {
  for (int i = 0; i < 4; i++) {
    if (digitalRead(BUTTONS[i]) == LOW) {
      analogWrite(MOTOR_1A, SPEEDS[i]);
      Serial.print("fan: ");
      Serial.println(NAMES[i]);
      delay(200);
    }
  }
}