Pressure sensor BMP180 for Arduino UNO

Using Arduino Networking, Protocols, and Devices
1

I got tiny board with pressure BMP180 and I want to use my Arduino UNO.

I found out that BMP180 require to be powered with 3.3V.

This sensor should connected with Arduino over I2C interface.

I have some questions to answer:

  • Firstly, I don't know how configure I2C, probably I need library for it, maybe it is built-in already.
    Which pins are used for I2C interface? Can I use any digital input?
  • How can I use pullup resistors for I2C if Arduino is powered with 5V and sensor with 3.3V?

I appreciate for any help. Thank you in advance.

2

I have already found answer for some questions. By default, SDA is on A4 and SCL on A5 pin.

I don't still know about voltage level translation between Arduino and sensor.

I have another question to answer: How can I configure I2C if I use more than one I2C device. I know I must assign different addresses for them but how can I do that?

3

I've found out about voltage level translation. I need to connect Mosfet N and rezystor 10k between 3.3V and 5V sides for 2 I2C lines.

I don't still know about how to assign I2C addresses for 2 devices.

4

I have the BMP180 breakout board from Adafruit (that link shows the BMP085, but they work identically) and I've not had to assign an address to it within my code (if I understand what you're saying...). The library that comes with it takes care of all of that for me. A similar breakout board from Sparkfun looks like it has a similar library.

If you don't have one of those two boards, does the manufacturer of your device provide such a library?

--Greg