#include <SoftwareSerial.h> 

int rx=4;                      // pins used to send data
int tx=6;

SoftwareSerial bluetoothSerial(rx,tx);

int ppm=0;

void setup() {
 bluetoothSerial.begin(9600);  // begin serial
 pinMode(rx,INPUT);
 pinMode(tx,OUTPUT);
}

void loop() {
  ppm=ppm+1;                    //increase the value by 1
  bluetoothSerial.print(ppm);   // print value
  delay(400);                   // wait 400 ms
}