Honeywell's HMC5883L——3-axis digital magnetometer designed for low-field magnetic sensing. it has a full-scale range of ±8 Guass and a resolution of up to 5 milli-Gauss.

you have to make it works with voltage between 2.16 and 3.6VDC.

It's very easy to communicate with this HMC5883L just through an I2C interface.

Click here you can buy a HMC5883L  breakout  Module

Features:

• Simple I2C interface

• 2.16-3.6VDC supply range

• Low current draw

• 5 milli-gauss resolution

Dimensions: 3.0x3.0x0.9mm

For more information about how to use this breakout please refer to our Wiki Page

Documents:

HMC5883L-Schematic.pdf
HMC5883L-FDS.pdf
HMC5883L.pdf