Hi,

I do not understand how to use the <i2c_t3.h> library for my application because one of my devices is using <Wire.h> through an instance of LightSensor. I need to run a secondary device on Wire1 and have tried using pins 29/30 and 16/17 in the below code.

The first I2C device (Light sensor) is working on pins 17/18 and my second I2C device (accelerometer) is not working. When I plug the accelerometer into pins 17/18 it works but the LightSensor has to be unplugged. Any guidance would be very helpful. Thanks.

This is my code:
Code:
#define HWSERIAL Serial1
#include <MFRC522.h>
#include <SPI.h>
#include <Wire.h>
#include "BH1750FVI.h"

#define VIB_PIN    6
#define RST_PIN    9   
#define SS_PIN    10    
#define SCK_PIN   13

BH1750FVI LightSensor;
MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

const int MPU_ADDR = 0x68; // I2C address of the MPU-6050. If AD0 pin is set to HIGH, the I2C address will be 0x69.
int16_t accelerometer_x, accelerometer_y, accelerometer_z; // variables for accelerometer raw data
int16_t temperature; // variables for temperature data
char tmp_str[7]; // temporary variable used in convert function

void RFID_reader() {

  if ( ! mfrc522.PICC_IsNewCardPresent()) 
  {
    return;
  }
  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) 
  {
    return;
  }
  //Show UID on serial monitor
  HWSERIAL.print("UID = ");
  String content= "";
  byte letter;
  for (byte i = 0; i < mfrc522.uid.size; i++) 
  {
     HWSERIAL.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
     HWSERIAL.print(mfrc522.uid.uidByte[i], HEX);
     content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
     content.concat(String(mfrc522.uid.uidByte[i], HEX));
  }
  
    HWSERIAL.println();

}

long TP_init(){
  long measurement=digitalRead(VIB_PIN);  //wait for the pin to get HIGH and returns measurement
  return measurement;
}

char* convert_int16_to_str(int16_t i) { // converts int16 to string. Moreover, resulting strings will have the same length in the debug monitor.
  sprintf(tmp_str, "%6d", i);
  return tmp_str;
}

void setup() {

  pinMode(VIB_PIN, INPUT);

  HWSERIAL.begin(9600);

  SPI.setSCK(SCK_PIN);
  SPI.begin();      // Init SPI bus
  mfrc522.PCD_Init();   // Init MFRC522
  
  LightSensor.begin();
  LightSensor.SetAddress(0x23);
  LightSensor.SetMode(Continuous_H_resolution_Mode);

  
  Wire1.begin();
  Wire1.beginTransmission(MPU_ADDR); // Begins a transmission to the I2C slave (GY-521 board)
  Wire1.write(0x6B); // PWR_MGMT_1 register
  Wire1.write(0); // set to zero (wakes up the MPU-6050)
  Wire1.endTransmission(true);
  
  
}

void loop() {
  
  RFID_reader();

  long measurement = TP_init();
  HWSERIAL.print("Vib = ");HWSERIAL.print(measurement);
  HWSERIAL.println();
  delay(100);

  uint16_t lux = LightSensor.GetLightIntensity();
  HWSERIAL.print("Lux = ");HWSERIAL.print(lux);
  HWSERIAL.println();

  
  Wire1.beginTransmission(MPU_ADDR);
  Wire1.write(0x3B); // starting with register 0x3B (ACCEL_XOUT_H) [MPU-6000 and MPU-6050 Register Map and Descriptions Revision 4.2, p.40]
  Wire1.endTransmission(false); // the parameter indicates that the Arduino will send a restart. As a result, the connection is kept active.
  Wire1.requestFrom(MPU_ADDR, 7*2, true); // request a total of 7*2=14 registers
  
  // "Wire.read()<<8 | Wire.read();" means two registers are read and stored in the same variable
  accelerometer_x = Wire1.read()<<8 | Wire1.read(); // reading registers: 0x3B (ACCEL_XOUT_H) and 0x3C (ACCEL_XOUT_L)
  accelerometer_y = Wire1.read()<<8 | Wire1.read(); // reading registers: 0x3D (ACCEL_YOUT_H) and 0x3E (ACCEL_YOUT_L)
  accelerometer_z = Wire1.read()<<8 | Wire1.read(); // reading registers: 0x3F (ACCEL_ZOUT_H) and 0x40 (ACCEL_ZOUT_L)
  temperature = Wire1.read()<<8 | Wire1.read();

  HWSERIAL.print("aX = ");HWSERIAL.print(convert_int16_to_str(accelerometer_x));
  HWSERIAL.println();
  delay(100);

  HWSERIAL.print("aY = ");HWSERIAL.print(convert_int16_to_str(accelerometer_y));
  HWSERIAL.println();
  delay(100);

  HWSERIAL.print("aZ = ");HWSERIAL.print(convert_int16_to_str(accelerometer_z));
  HWSERIAL.println();
  delay(100);

  HWSERIAL.print("Temp = ");HWSERIAL.print(temperature/340.00+36.53);
  HWSERIAL.println();
  delay(100);
  
  
}