// Send digital signal from motion detector
// to the Atari joystick port pin 1
// via the Arduino digital pin 4

const int Digital_In = 2;  // Digital in from motion sensor
const int Digital_Out = 4; // Digital out to Atari
int MotionState = LOW;        // current state of pin
  
void setup()
{
  pinMode(Digital_In, INPUT);   // Set pin 2 to input
  pinMode(Digital_Out, OUTPUT);  // Set pin 4 to output
  pinMode(LED_BUILTIN, OUTPUT); // Set LED for feedback
}

void loop() 
{
  MotionState = digitalRead(Digital_In);   // read new motion state

  if (MotionState == HIGH) // Motion detected?
  { 
    digitalWrite(Digital_Out, HIGH); // send HIGH bit (1) to Atari
    digitalWrite(LED_BUILTIN, HIGH); // turn on the LED
  }
  else
  if (MotionState == LOW) // Motion not detected?
  {  
    digitalWrite(Digital_Out, LOW); // send LOW bit (0) to Atari
    digitalWrite(LED_BUILTIN, LOW); // turn off the LED
  }
}