I2C Connection between different Arduino boards

[bugerman]

Hello,

I2C onnection works on:
UNO with UNO
Leonardo with Leonardo

But UNO with Leonardo did not work.
Please help me understand why it does not work, and what need to do.

Thanks

[sterretje]

1. Post your schematic how the two boards are connected.
2. Is anything connected to other pins? Post your code.
   To post code, use edit -> copy for forum in the IDE and next paste it here in a reply.

[bugerman]

1.
UNO is Slave / Leonardo is Master

2.
Anything else not connected to Arduino.
The target is: Leonardo sending a Value -> UNO receiving a value and turning on Arduino led.

Master (Leonardo)

#include<Wire.h>
int LED = 13;
int x = 0;

void setup() {
  Serial.begin(9600);
  pinMode(LED, OUTPUT);
  Wire.begin(); 
}

void loop() {
  Serial.println(x);
  digitalWrite(LED, HIGH);
  delay(500);
  x = 3;
  Wire.beginTransmission(9);
  Wire.write(x);
  Wire.endTransmission();
 
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(200);
}

Slave (UNO)

#include<Wire.h>
int LED = 13;
int x = 0;

void setup() {
  Serial.begin(9600);
  pinMode (LED, OUTPUT);
  Wire.begin(9); 
  Wire.onReceive(receiveEvent);
}

void loop() {
  Serial.println(x);
  if (x == 3) {
    Serial.print("Hello - 1\n");
    digitalWrite(LED, HIGH);
    delay(200);
    digitalWrite(LED, LOW);
    delay(200);
    
    digitalWrite(LED, HIGH);
    delay(200);
    digitalWrite(LED, LOW);
    delay(200);
    
    digitalWrite(LED, HIGH);
    delay(200);
    digitalWrite(LED, LOW);
    delay(5000);
  }
  if (x == 0) {
    Serial.print("Hello - 2\n");
    digitalWrite(LED, HIGH);
    delay(400);
  }
}

void receiveEvent(int bytes) {
  x = Wire.read();
}

[bugerman]

Resolved, was a bad connection