TX

// Include VirtualWire library
#include <VirtualWire.h>

int led_pin = 13;
int transmit_pin = 10;
int pir_pin = 12;
int val = 0;
int pir_state = LOW;

void setup()
{
   Serial.begin(19200);
   vw_set_tx_pin(transmit_pin);
   vw_setup(4000); // Transmission rate
   pinMode(led_pin, OUTPUT);
   pinMode(pir_pin,INPUT);
   delay(20000); // give time to get out the door
}

void loop()
{
   char msg[1] = {'0'};
  // Get sensor value
  val = digitalRead(pir_pin);
  // Change message if motion is detected
  if (val == 1)
  {
      msg[0] = '1';
      digitalWrite(led_pin, HIGH); // Flash a light to show transmitting
      vw_send((uint8_t *)msg, 1);
      vw_wait_tx(); // Wait until the whole message is gone
      Serial.println("Motion detected!");
      pir_state = HIGH;
      }

  else
 {
      Serial.println("Motion ended!");
      digitalWrite(led_pin, LOW);
      pir_state = LOW;
   }
}