#include "SoftwareSerial.h"

// Declare and initialize UART pins
const int rx_pin = 4;
const int tx_pin = 5;

// Declare and initialize led pin
const int led_pin = 9;

// Create new serial with specified UART pins
SoftwareSerial mySerial(rx_pin , tx_pin);


void setup(){ 
  // Set the pin modes of UART pins
  pinMode(rx_pin, INPUT); // Receiving requires input
  pinMode(tx_pin, OUTPUT); // Transmitting requires output

  // Set led as output
  pinMode(led_pin, OUTPUT);

  // Start the serial communication at 9600 bits/sec
  mySerial.begin(9600);
}


void loop(){ 
  mySerial.println("100"); // Send the message "100"

  // Flash the LED
  digitalWrite(led_pin,HIGH);
  delay(100);
  digitalWrite(led_pin,LOW);

  // Wait some time (500ms in total)
  delay(400);
}