Connecting to 3.3V accelerometer

Other Hardware General Electronics
1

I bought this accelerometer:

I realized it uses up to 3.6V power supply.

And I want to run it with this RBBB kit I have:

http://shop.moderndevice.com/products/rbbb-kit

The kit is intended for 5V arduino. I used it for a 5V analog output accelerometer with success.

Now if I want to convert between 3.3V accelerometer power and logic and 5V arduino power and logic, what is the easiest way? Do I need both a logic level converter and a 3.3V regulator, right? The RBBB has no 3.3V supply like Duemilanove does. Thanks.

2

I also have that accelerometer. I ran it with my Uno, which has the 3V3 supply available, but 5V I/O. It survived, but the pull-up resistors to 3V3 supplied by another component (Barometric Pressure Sensor - BMP085 Breakout - SEN-09694 - SparkFun Electronics) may have mitigated the potential negative effects.

I eventually got a logic level converter, which allows everything to run at the proper voltages http://www.sparkfun.com/products/8745

3

I haven't tried this, but the sensor supports I2C. Since I2C requires pull-up resistors, couldn't you use external pull-up resistors and pull-up the I2C to 3.3V instead of 5V?

4

theepdinker:
I also have that accelerometer. I ran it with my Uno, which has the 3V3 supply available, but 5V I/O. It survived, but the pull-up resistors to 3V3 supplied by another component (http://www.sparkfun.com/products/9694) may have mitigated the potential negative effects.

I eventually got a logic level converter, which allows everything to run at the proper voltages http://www.sparkfun.com/products/8745

Hey thanks. I will get some 3.3V regulator and a logic converter.

5

Thank you James. I'll see if I can do that. Since the I2C arduino library probably has a command to enable internal pullup resistors, should I try to seek and disable that command if I pull up the line to 3.3V? How about the clock line?

6

should I try to seek and disable that command if I pull up the line to 3.3V? How about the clock line?

Yes. I believe the Arduino library enables the pull-ups by default but I don't remember. Based on the datasheet for your part, both the clock and data lines need to be pulled to 3.3V. The part's absolute max rating for I/O is 3.6V.

7

Thanks James. I'll give it a shot later. I have an older adxl3xx with analog outputs. Hope I can run the new one before a competition I'm entering into :slight_smile: