Could someone help me to use a second slave on i2c

Hi everyone,
I need help regarding the connection of another I2Cparticipant. I hope someone could help me and tell me how the PCA9685 should be connected and with what resistors it should be. And how would i have to extend my code so that the PCA9685 can communicate via I2C?

My circuit is the following (irrelavante such as other sensors removed):

My code for the master (unrelated code removed):

#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>

//Lenken
#define PWM_FREQUENCY_HZ 60      // Frequency of PWM signals
#define PCA_CHANNEL_SERVO 0      // Board PCA9685: servo channel
#define PWM_SERVO_CENTER 390     // Neutral position in 0..4095
#define PWM_SERVO_MAX_DELTA 120  // Max. +/- deviation from neutral position


// PWM servo driver module
#define PWM_CHANNEL_ESC 1
#define PWM_NEUTRAL 400
#define PWM_DRIVE 415
#define PWM_BACKWARDS 380

Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();

//Lenken
int minPulse = PWM_SERVO_CENTER - PWM_SERVO_MAX_DELTA;
int maxPulse = PWM_SERVO_CENTER + PWM_SERVO_MAX_DELTA;

char distance_Char[] = "V"

void setup() {
  Wire.begin();  // join i2c bus (address optional for master)
  Serial.begin(9600);

}

void loop() {

  /*pwm.setPWM(PWM_CHANNEL_ESC, 0, PWM_DRIVE) 
this doesn't work yet because i'm already using scl and sda to connect both arduinos*/

  Serial.println(distance_Char);
  Wire.beginTransmission(4);          // transmit to device #4
  Wire.write(distance_Char);  // sends five bytes
  Wire.endTransmission();             // stop transmitting

}

My code for the slave (unrelated code removed):

#include <SoftwareSerial.h>
#include <Wire.h>

SoftwareSerial BT(4, 2);

char myChar;

void setup() {
  BT.begin(9600);                // set the data rate for the SoftwareSerial port
  Wire.begin(4);                 // join i2c bus with address #4
  Wire.onReceive(receiveEvent);  // register event
  Serial.begin(9600);
  pinMode(8, OUTPUT);
}
void loop() {
  while (BT.available()) {
    myChar = BT.read();
    if (myChar == 'V') {
     Serial.println("Hi")
    }
  }
}

void receiveEvent(int howMany) {
  int charCount = 0;
  while (Wire.available()) {  // loop through all but the last
    char c = Wire.read();     // receive byte as a character

    if (c == '#') {
      BT.println("Hi");
  }
}

Baased on your diagram, the first thing I note is you miss the GND connection between the two Arduinos. I hope it's not missing in the real hardware wiring anyway.
The second issue is you shouldn't connect the PCA9685 V+ pin to Arduino because this is the power for the motors, and Arduino can't power them directly (you need an external source, and connect it to the two screw connectors V+/GND).
Going back to your question, as I2C is a bus based communication line, you just need to connect all SDAs and SCLs together (SDA to the green line, SCL to the yellow one), then both are usually connected to two pull-up resistors to 5V.
Once done, and get over hardware issues, you can start talking about coding.

Closing in favor of @ard54z7564's other topic on the subject in the Deutsch forum category: