I2C between Arduino's

Step 2 Hardware

 The Hardware for the I2C is simple. You just need to connect all the Arduino's by two wires to Analog Pin 3 and Analog Pin 4.  Because the I2C BUS cannot stay at 0 V. To solve this, we put two Pull-Up resistors connected to 5V.

The Pull-Up resistors should be between 1,5 K and 47 K. In this example i personally used 1,5 K.

Comments

[chris911ny]

I have read in some articles that the wire library will enable internal pull-ups, is that the case or we really need to add pull-ups?

[jeremyvnc]

Pins 4 & 5 are SDA and SCLK for I2C

[easydaman]

Nice! Thanks man!
A little sidenote for when working with an Arduino Mega: Comm-Pins are 20 and 21. But well... figuring that out takes 5 minutes. On the other hand: you just saved them ;-)

[tekkentux]

Is that pin 3 and 4 (as in the text), or pin 4 and 5 (as in the picture)? Thank you!