How can I send and receive data from an Arduino Uno to Arduino Mega using I2C?

Question

I am trying to send data as a string from an Arduino Uno to another Arduino Mega. I have read about the I2C connection where we connect the RX to TX oppositely.

How to start and send and receive data between them? I have no idea how the code can be written.

Answer 1

At instructables there is a good post.

In short the code is

Master code:

// Include the required Wire library for I2C
#include <Wire.h>
int x = 0;
void setup() {
 // Start the I2C Bus as Master
 Wire.begin(); 
}
void loop() {
 Wire.beginTransmission(9); // transmit to device #9
 Wire.write(x); // sends x 
 Wire.endTransmission(); // stop transmitting
 x++; // Increment x
 if (x > 5) x = 0; // `reset x once it gets 6
 delay(500);
}

Slave code

// Include the required Wire library for I2C
#include <Wire.h>
int LED = 13;
int x = 0;
void setup() {
 // Define the LED pin as Output
 pinMode (LED, OUTPUT);
 // Start the I2C Bus as Slave on address 9
 Wire.begin(9); 
 // Attach a function to trigger when something is received.
 Wire.onReceive(receiveEvent);
}
void receiveEvent(int bytes) {
 x = Wire.read(); // read one character from the I2C
}
void loop() {
 //If value received is 0 blink LED for 200 ms
 if (x == '0') {
 digitalWrite(LED, HIGH);
 delay(200);
 digitalWrite(LED, LOW);
 delay(200);
 }
 //If value received is 3 blink LED for 400 ms
 if (x == '3') {
 digitalWrite(LED, HIGH);
 delay(400);
 digitalWrite(LED, LOW);
 delay(400);
 }
}

In the instructables post a lot more explanation is shown.