I need help with connecting two sensors

Currently I have a project. I need to combine MAX30102 sensor and ADXL345 accelerameter. What I am trying to do here is get chest movements from accelerameter; heart rate and blood oxygen rate from other sensor.

I make them work separetely but I'm not sure how to combine them.

I am using arduino UNO and when I connect them separetely I use A4 and A5 pins to SDA and SCL for both sensor.

So if I want to combine them I wasn't sure for which pins I need to use and how I can start the sensors on arduino code.

I have also some questions about combining the code, but before wiring checks out I can not be certain about the code.

You can use same pins I2C, A4 and A5, SDA and SCL, to both sensors.
The sensor have diferentes I2C address.

Using " < code > " from tools bar, post your code.

Ref: " https://www.analog.com/media/en/technical-documentation/data-sheets/max30102.pdf
2C Write Address AE Hex
I2C Read Address AF Hex

Ref: " https://www.analog.com/media/en/technical-documentation/data-sheets/adxl345.pdf
Address 0x2C

/*
  Based on Arduino Library Example
*/

#include <Wire.h>
#include "MAX30105.h"
#include "spo2_algorithm.h"
#include <Adafruit_Sensor.h>
#include <Adafruit_ADXL345_U.h>

MAX30105 particleSensor;

#define MAX_BRIGHTNESS 255

#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)
//Arduino Uno doesn't have enough SRAM to store 100 samples of IR led data and red led data in 32-bit format
//To solve this problem, 16-bit MSB of the sampled data will be truncated. Samples become 16-bit data.
uint16_t irBuffer[100]; //infrared LED sensor data
uint16_t redBuffer[100];  //red LED sensor data
#else
uint32_t irBuffer[100]; //infrared LED sensor data
uint32_t redBuffer[100];  //red LED sensor data
#endif

int32_t bufferLength; //data length
int32_t spo2; //SPO2 value
int8_t validSPO2; //indicator to show if the SPO2 calculation is valid
int32_t heartRate; //heart rate value
int8_t validHeartRate; //indicator to show if the heart rate calculation is valid

byte pulseLED = 11; //Must be on PWM pin
byte readLED = 13; //Blinks with each data read

Adafruit_ADXL345_Unified accel = Adafruit_ADXL345_Unified();

void setup()
{
  Serial.begin(115200); // initialize serial communication at 115200 bits per second:

  pinMode(pulseLED, OUTPUT);
  pinMode(readLED, OUTPUT);

  // Initialize sensor

  if(!accel.begin())
  {
    Serial.println("No valid sensor found");
    while(1);
  }


  if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) //Use default I2C port, 400kHz speed
  {
    Serial.println(F("MAX30102 was not found. Please check wiring/power."));
    while (1);
  }

  Serial.println(F("Attach sensor to finger with rubber band. Press any key to start conversion"));
  while (Serial.available() == 0) ; //wait until user presses a key
  Serial.read();

  byte ledBrightness = 60; //Options: 0=Off to 255=50mA
  byte sampleAverage = 4; //Options: 1, 2, 4, 8, 16, 32
  byte ledMode = 2; //Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
  byte sampleRate = 100; //Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
  int pulseWidth = 411; //Options: 69, 118, 215, 411
  int adcRange = 4096; //Options: 2048, 4096, 8192, 16384

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

void loop()
{
  bufferLength = 100; //buffer length of 100 stores 4 seconds of samples running at 25sps

  //read the first 100 samples, and determine the signal range
  for (byte i = 0 ; i < bufferLength ; i++)
  {
    while (particleSensor.available() == false) //do we have new data?
      particleSensor.check(); //Check the sensor for new data

    redBuffer[i] = particleSensor.getRed();
    irBuffer[i] = particleSensor.getIR();
    particleSensor.nextSample(); //We're finished with this sample so move to next sample

    Serial.print(F("red="));
    Serial.print(redBuffer[i], DEC);
    Serial.print(F(", ir="));
    Serial.println(irBuffer[i], DEC);

    
  }

  //calculate heart rate and SpO2 after first 100 samples (first 4 seconds of samples)
  maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);

  //Continuously taking samples from MAX30102.  Heart rate and SpO2 are calculated every 1 second
  while (1)
  {
    //dumping the first 25 sets of samples in the memory and shift the last 75 sets of samples to the top
    for (byte i = 25; i < 100; i++)
    {
      redBuffer[i - 25] = redBuffer[i];
      irBuffer[i - 25] = irBuffer[i];
    }

    //take 25 sets of samples before calculating the heart rate.
    for (byte i = 75; i < 100; i++)
    {
      while (particleSensor.available() == false) //do we have new data?
        particleSensor.check(); //Check the sensor for new data

      digitalWrite(readLED, !digitalRead(readLED)); //Blink onboard LED with every data read

      redBuffer[i] = particleSensor.getRed();
      irBuffer[i] = particleSensor.getIR();
      particleSensor.nextSample(); //We're finished with this sample so move to next sample

      //send samples and calculation result to terminal program through UART
      Serial.print(F("red="));
      Serial.print(redBuffer[i], DEC);
      Serial.print(F(", ir="));
      Serial.print(irBuffer[i], DEC);

      Serial.print(F(", HR="));
      Serial.print(heartRate, DEC);

      Serial.print(F(", HRvalid="));
      Serial.print(validHeartRate, DEC);

      Serial.print(F(", SPO2="));
      Serial.print(spo2, DEC);

      Serial.print(F(", SPO2Valid="));
      Serial.println(validSPO2, DEC);
    }

    //After gathering 25 new samples recalculate HR and SP02
    maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);
  }
  sensors_event_t event; 
  accel.getEvent(&event);
  Serial.print("X: "); Serial.print(event.acceleration.x); Serial.print("");
  Serial.print("Y: "); Serial.print(event.acceleration.y); Serial.print("");
  Serial.print("Z: "); Serial.print(event.acceleration.z); Serial.print("");
  Serial.println("m/s^2 ");
  delay(500);
}

Code is Like this right now. I'm not really experienced in arduino codes, so these are mostly from web guides.

I tried to combine them but not exactly sure about how to do so.

Also even if I wanted to write adresses for I2C what is the syntax for this?

This is the current schematic.

Does your code work the way you expect it to?

Post the stand alone sketch that works only for MAX30102 sensor.

Post the stand alone sketch that works only for ADXL345 sensor.

After that I wish to workaround to show you combining the two sketches.

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