#define PROCESSING_VISUALIZER 1
#define SERIAL_PLOTTER  2
#include <SoftwareSerial.h>
//  Variables
int pulsePin = 0;                 // Pulse Sensor purple wire connected to analog pin 0
 
// Volatile Variables, used in the interrupt service routine!
volatile int BPM;                   // int that holds raw Analog in 0. updated every 2mS
volatile int Signal;                // holds the incoming raw data
volatile int IBI = 600;             // int that holds the time interval between beats! Must be seeded!
volatile boolean Pulse = false;     // "True" when User's live heartbeat is detected. "False" when not a "live beat".
volatile boolean QS = false;        // becomes true when Arduoino finds a beat.
SoftwareSerial BTSerial(2, 3);
 
// SET THE SERIAL OUTPUT TYPE TO YOUR NEEDS
// PROCESSING_VISUALIZER works with Pulse Sensor Processing Visualizer
//      https://github.com/WorldFamousElectronics/PulseSensor_Amped_Processing_Visualizer
// SERIAL_PLOTTER outputs sensor data for viewing with the Arduino Serial Plotter
//      run the Serial Plotter at 115200 baud: Tools/Serial Plotter or Command+L
static int outputType = SERIAL_PLOTTER;
 
 
void setup(){ 
  Serial.begin(9600);             // we agree to talk fast!
  BTSerial.begin(9600);
  interruptSetup();                 // sets up to read Pulse Sensor signal every 2mS
   // IF YOU ARE POWERING The Pulse Sensor AT VOLTAGE LESS THAN THE BOARD VOLTAGE,
   // UN-COMMENT THE NEXT LINE AND APPLY THAT VOLTAGE TO THE A-REF PIN
//   analogReference(EXTERNAL);
}
 
 
//  Where the Magic Happens
void loop(){
 
    serialOutput() ;
  if (QS == true){     // A Heartbeat Was Found
                       // BPM and IBI have been Determined
                       // Quantified Self "QS" true when arduino finds a heartbeat
                                // Set 'fadeRate' Variable to 255 to fade LED with pulse
        serialOutputWhenBeatHappens();   // A Beat Happened, Output that to serial.
        QS = false;                      // reset the Quantified Self flag for next time
  }
  delay(1000);
}
 
void serialOutput(){   // Decide How To Output Serial.
  switch(outputType){
    case PROCESSING_VISUALIZER:
      sendDataToSerial('S', Signal);     // goes to sendDataToSerial function
      break;
    case SERIAL_PLOTTER:  // open the Arduino Serial Plotter to visualize these data
      Serial.print(BPM);
      Serial.print(",");
      Serial.print(IBI);
      Serial.print(",");
      Serial.println(Signal);
      BTSerial.print(BPM);
      break;
    default:
      break;
  }
 
}
 
//  Decides How To OutPut BPM and IBI Data
void serialOutputWhenBeatHappens(){
  switch(outputType){
    case PROCESSING_VISUALIZER:    // find it here https://github.com/WorldFamousElectronics/PulseSensor_Amped_Processing_Visualizer
      sendDataToSerial('B',BPM);   // send heart rate with a 'B' prefix
      sendDataToSerial('Q',IBI);   // send time between beats with a 'Q' prefix
      BTSerial.print(BPM);
      break;
 
    default:
      break;
  }
}
 
//  Sends Data to Pulse Sensor Processing App, Native Mac App, or Third-party Serial Readers.
void sendDataToSerial(char symbol, int data ){
    Serial.print(symbol);
    Serial.println(data);
  }
 
위의 코드로 블루투스 모듈을 사용하여 앱에 bpm을 띄우고 있는데 어쩌다 한번씩 bpm값이 겹쳐서 나오는 경우가 발생합니다. 어느 부분이 문제가 되는 걸까요? 시리얼 모니터 상에서는 그런 현상이 없는데 스마트폰에 디스플레이 할 때만 이런 문제가 발생합니다.