I2C help?

Hi, im after some help (it may be a stupid question as ive never done anything with I2C) but i have device that comminucates to other devices (slaves) using I2C. So, the salve in this case would be my arduino, but i want to add this breakout board MPL3115A2 Altitude/Pressure Sensor Breakout, which states it communicats over I2C?

So what do i do in this case where i have two devices that want to communicate over I2C?

Thanks
Andy

You need to first understand Bus Arbitration: http://www.esacademy.com/en/library/technical-articles-and-documents/miscellaneous/i2c-bus/general-introduction/bus-arbitration.html

Every I2C device has an address. You can connect lots of them on the same wires.

fungus: Every I2C device has an address. You can connect lots of them on the same wires.

Fine for multiple slave devices, but multi-master takes a little more care and attention.

majenko:

fungus: Every I2C device has an address. You can connect lots of them on the same wires.

Fine for multiple slave devices, but multi-master takes a little more care and attention.

Oh, I see what you mean. There's one device treating the Arduino as a slave and the Arduino has to treat a different device as a slave. Yes, that's difficult.

I'd be tempted to bit-bang the communication with the sensor. I2C isn't complicated (and I'd be surprised if a google for "SoftI2C" doesn't turn up something...)