The car odometer can display the mileage of the car, which is based on the number of rotations of the wheels to indirectly derive the mileage. The number of wheel revolutions can be measured with a Hall sensor, which is an important part of the odometer. Its performance plays an extremely important role in the work of the whole circuit.

The magnet is attached to the iron and fixed at a certain position on the wheel. The Hall circuit is fixed on the frame. For each revolution of the wheel, the magnet passes through the Hall IC once and generates a pulse signal, and the counter counts the pulse.

Hall sensors commonly used in odometers are mostly bipolar latch Hall switch.