< MAX30102 모듈 작동 원리 >
▷ 통합 발광체: 내부의 적색 LED와 적외선(IR) LED가 빛을 발사한다.
▷ 광검출기: 혈액 내 헤모글로빈이 빛을 흡수하고 남은 반사광을 측정한다.
▷ 데이터 변환: 내부의 저소음 아날로그-디지털 변환기(ADC)가 신호를 디지털 데이터로 변환한다.
▷ 통신 방식: 표준 I2C 인터페이스를 사용하여 선 2개(SDA, SCL)로 데이터를 전송한다.

★ MAX30102  라이브러리 설치 하면 예제가 있다
File --> Examples --> SparkFun MAX3010x Pulse and Proximity Sensor Library --> Example1_Basic_Readings

---<  MAX30102_Basic- Reading.ino  >-------------------------------------------------------------------------
#include <Wire.h>
#include "MAX30105.h"
MAX30105 particleSensor;

#define debug Serial //Uncomment this line if you're using an Uno or ESP
//#define debug SerialUSB //Uncomment this line if you're using a SAMD21

void setup()
{
  debug.begin(9600);
  debug.println("MAX30105 Basic Readings Example");

  // Initialize sensor
  if (particleSensor.begin() == false)
  {
    debug.println("MAX30105 was not found. Please check wiring/power. ");
    while (1);
  }

  particleSensor.setup(); //Configure sensor. Use 6.4mA for LED drive
}

void loop()
{
  debug.print(" R[");
  debug.print(particleSensor.getRed());
  debug.print("] IR[");
  debug.print(particleSensor.getIR());
  debug.print("] G[");
  debug.print(particleSensor.getGreen());
  debug.print("]");

  debug.println();
}
---------------------------------------------------------------------------------------------------

---<  MAX30102_HeartRate.ino  >----------------------------------------------------------------
#include <Wire.h>
#include "MAX30105.h"

MAX30105 particleSensor; // initialize MAX30102 with I2C

void setup() {
  Serial.begin(115200);
  while(!Serial); //We must wait for Teensy to come online
  delay(100);
  Serial.println("");
  Serial.println("MAX30102");
  Serial.println("");
  delay(100);
  // Initialize sensor
  if (particleSensor.begin(Wire, I2C_SPEED_FAST) == false) //Use default I2C port, 400kHz speed
  {
    Serial.println("MAX30105 was not found. Please check wiring/power. ");
    while (1);
  }

  byte ledBrightness = 70; //Options: 0=Off to 255=50mA
  byte sampleAverage = 1; //Options: 1, 2, 4, 8, 16, 32
  byte ledMode = 2; //Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
  int sampleRate = 400; //Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
  int pulseWidth = 69; //Options: 69, 118, 215, 411
  int adcRange = 16384; //Options: 2048, 4096, 8192, 16384

  //Configure sensor with these settings
  particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange);

}

void loop() {
  particleSensor.check(); //Check the sensor
  while (particleSensor.available()) {
      // read stored IR
      Serial.print(particleSensor.getFIFOIR());
      Serial.print(",");
      // read stored red
      Serial.println(particleSensor.getFIFORed());
      // read next set of samples
      particleSensor.nextSample();     
  }
}
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