uint8_t buf[8] = { 0 }; //Keyboard report buffer

#define PIN_W 4 // Pin for w
#define PIN_A 5 // Pin for a
#define PIN_S 6 // Pin for s
#define PIN_D 7 // Pin for d

int potVal = 0;

void setup() {
  Serial.begin(9600); // Setup Serial communication

  //Set pinmode of Input pins
  pinMode(PIN_W, INPUT);
  pinMode(PIN_A, INPUT);
  pinMode(PIN_S, INPUT);
  pinMode(PIN_D, INPUT);
}

void loop() {

  //When button representing W is pressed
  if (digitalRead(PIN_W) == HIGH) {
    buf[2] = 26; // W keycode
    Serial.write(buf, 8); // Send keypress
    Serial.println("Button 4 Pressed");
    releaseKey();
  }

  //When button representing A is pressed
  if (digitalRead(PIN_A) == HIGH) {
    buf[2] = 4; // A keycode
    Serial.write(buf, 8); // Send keypress
    Serial.println("Button 5 Pressed");
    releaseKey();
  }

  //When button representing S is pressed
  if (digitalRead(PIN_S) == HIGH) {
    buf[2] = 22; // S keycode
    Serial.write(buf, 8); // Send keypress
    Serial.println("Button 6 Pressed");
    releaseKey();
  }

  //When button representing D is pressed
  if (digitalRead(PIN_D) == HIGH) {
    buf[2] = 7; // D keycode
    Serial.write(buf, 8);
    Serial.println("Button 7 Pressed");
    releaseKey();
  }

  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  if ( sensorValue != potVal ) {
    // print out the value you read:
    Serial.println(sensorValue);
    delay(1);  // delay in between reads for stability
    potVal = sensorValue;
  }
}

// Function for Key Release
void releaseKey() {
  buf[0] = 0;
  buf[2] = 0;
  Serial.write(buf, 8); // Send Release key
}