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Author Topic: How do I interface a 5v & 3.3v arduino  (Read 601 times)
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Jr. Member
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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)?
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Brattain Member
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You can use any of those methods. However you can also use a potential divider, that's just two resistors.
http://en.wikipedia.org/wiki/Voltage_divider
To cut down the 5V signal to 3v3
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Shannon Member
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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.
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thanks, that sure seems easier, so I'm experimenting with the voltage divider now.
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