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Topic: Arduino DUE and Pro Micro (Read 531 times) previous topic - next topic


Mar 30, 2015, 11:46 am Last Edit: Mar 30, 2015, 03:15 pm by b_barbosa

I'd like to have I2C communication between Arduino DUE and Arduino Pro Micro (5V version). The 3.3V voltage of DUE is a compatibility problem on I2C Bus??

Bruno Barbosa


No. You can connect the I2C pullups to 3.3v and both sides will work. It's not going to be reliable for cable longer than 10cm.

It appears the Pro Micro doesn't have any built-in pullups, so the ones on the Due board (for the main I2C pins) will be OK.
"The problem is in the code you didn't post."


Hi Morgan,

Final questions:
There are any chance of permanent damage in DUE because the working voltage of Micro is 5.0V and Due 3.3V?
The I2C bus will work at 5.0V?
And finally, my cable have 25cm is that a problem in I2C bus?

Thanks again.


1. If you don't have any pullups to 5v then you will be OK.
2. No, the I2C bus will work at 3.3v.
3. Maybe. It might work. Is it a ribbon cable? Don't run SDA and SCL next to each other. Put a ground wire or power wire in between. Most devices put those pins together, so all my ribbon cables have some wires twisted over each other at both ends.
"The problem is in the code you didn't post."

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