GY-271 HMC5883L 3-Axis Digital Compass Module

The HMC5883L reads the Earth's magnetic field across three axes and turns that into a compass heading, the same underlying sensing principle a physical compass needle uses but read out digitally over I2C rather than watched visually. Heading accuracy runs to within 1-2 degrees, precise enough for real navigation logic rather than a rough directional guess.

A built-in 12-bit ADC and onboard amplification mean the raw magnetic field reading arrives already converted to a usable digital value, with automatic degaussing and offset cancellation handling the calibration drift that magnetometers are prone to. Data updates up to 160 times per second, fast enough to track a moving vehicle's heading in real time rather than only a stationary reading.

Common uses are robot and drone heading sensors, compass-based navigation projects, and any build needing to know which direction it is currently facing rather than just how it has moved.