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Topic: Logic level converter help [Solved] (Read 855 times) previous topic - next topic


Jan 16, 2012, 10:12 pm Last Edit: Jan 16, 2012, 11:55 pm by madvoid Reason: 1
Hi all,

I am trying to interface a bmp085 breakout (from Sparkfun) with an Arduino Mega.  The sensor works fine with a 3.3V supply and connected straight to SDA and SCL but the trouble comes when I try to use the sensor with a logic level converter (also from sparkfun).  The sensor sends the data but it's completely wrong.  I did a simple test where I turned a digital pin on and off through the logic level converter and a resistor and the voltage on the low side of the converter was around 2.2 Volts.  I was expecting it to be somewhere around 3.3 V.  Did I fry the logic level converter or is that within its tolerances? The only reason I'm bothering with a logic level converter is because I will need to use 5V I2C devices on the same bus.

I have included a picture of my setup

Thanks in advance for any help or advice!


I2C signals are bidirectional. This means you have to use a Tx channel for each of the two signals, not one Tx and one Rx channel.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.


Wow, that was a lot simpler solution than I thought it would be. I'm sorry for asking such an obvious question, thank you very much for your help!

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