Honeywell’s HMC5883L 3-Axis Magnetometer can measure both the direction and the magnitude of Earth’s magnetic fields. Think of it as a Digital Compass.
HMC5883L features low-voltage operation (2.16 to 3.6V) and low-power consumption (100 μA) thus an excellent choice for battery powered applications. It has 12-bit ADC that enables 1° to 2° compass heading accuracy. The Board supports I2C (2-wire) digital interface.
Applications: These tiny sensors are used in Cell Phones to detect your heading in GPS/Maps application. Their applications include and are not limited to Auto Navigation Systems, like Unmanned Aerial Vehicles for finding the Heading and Personal Navigation Devices.
According to Honeywell’s HMC5983 Datasheet (.pdf), the Circuit Board containing this sensor should not bear any Power or Ground plane/ traces on the Bottom side of the Printed Circuit Board below the sensor. Since the HMC5983 sensor is similar to the HMC5883L sensor (with an added benefit of SPI capability), we followed the guideline. Hence, the back side of our board looks like this:
The Board has Two Pull-Up resistors for SDA (Serial Data) and SCL (Serial Clock) lines. The suggested value for Pull-Ups is 2.2K.
Just connect our Board as shown in the pictures. It is suggested to use a Logic Level Converter between the (5V) Microcontroller and the (3.3V) HMC5883L Sensor. The default (factory) HMC5883L 8-bit slave address is 0x3C for write operations, or 0x3D for read operations.