How do I interface a 5v & 3.3v arduino

Forum 2005-2010 (read only) Hardware Interfacing
1

I have an arduino running a 5V sensor array that I want to actuate outputs on an arduino operating at 3.3v. Do I need to use an optoisolator, relay or can this be accomplished using a bipolar transistor (like a PN2222)?

2

You can use any of those methods. However you can also use a potential divider, that's just two resistors.

To cut down the 5V signal to 3v3

3

In fact with a voltage divider you will probably be able to communicate both directions since the input-high voltage level is 2.7V for an ATmega at 5V supply, so a 3.3V driving it will register.

4

thanks, that sure seems easier, so I'm experimenting with the voltage divider now.