GY-271 HMC5883L 3-Axis Magnetic Electronic Compass Module is designed for low-field magnetic sensing with a digital interface and it is perfect to give precise heading information. This compact sensor fits into small projects such as UAVs and robot navigation systems. The sensor converts any magnetic field to a differential voltage output on 3 axes. This voltage shift is the raw digital output value, which can then be used to calculate headings or sense magnetic fields coming from different directions.