This is a breakout board for Honeywell's HMC5883L, a 3-axis digital compass.
Communication with the HMC5883L is simple and all done through an I2C interface.
There is no on-board regulator, so a regulated voltage of 2.16-3.6VDC should be supplied.

The breakout board includes the HMC5883L sensor and all filtering capacitors as shown. The power and 2-wire interface pins are all broken out to a 0.1" pitch header.

Features:

• Simple I2C interface
• 2.16-3.6VDC supply range
• Low current draw
• 5 milli-gauss resolution

Dimensions: 0.7x0.7" (17.78x17.78mm)

 

Documents:

• Schematic
• Eagle Files
• Datasheet (HMC5883L)
• Example code (Arduino)
• Bildr Tutorial
• Digital Compass How-To Video