Hall Effect sensors explained: Stick drift, magnets & more

Stick drift has become the scourge of modern controllers, but surprisingly, this was a problem that was solved long ago using magnets and something called the Hall Effect.

Though more associated with the Nintendo Switch Joycons, Stick Drift is an issue that affects the majority of modern controllers, Nintendo, Sony, and Microsoft alike. As this issue came to prominence, some vendors started offering controllers with ‘Hall Effect’ analog sticks that were said to be immune to Stick Drift. But what is the Hall Effect? And can it really eliminate Drift?

What is Stick Drift?

The ‘drift’ of an analog stick is when the stick is picking up inputs the user is not making. For example, your character could move or the camera can turn without the player ever touching the analog stick.

The reason this happens is that most modern analog sticks use small components called potentiometers to measure the position of the stick and send that data to the console or computer. Potentiometers use electrical resistance to track this information.

Each potentiometer has a resistor which takes the form of a curved track. A contact arm follows this track, causing the resistance to increase or decrease. By using two potentiometers, one for the X-axis and one for the Y-axis, you can get very accurate data on the position of the stick.

Wikimedia, Pexels

Potentometers are cheap and easy to make, but they do have a drawback. Since the contact arm does make physical contact with the resistance track, this can cause it to wear out over time, causing the resistance readings to become unreliable and ultimately leading to Drift.

What is a Hall Effect sensor & how does it help?

A Hall effect sensor is a type of sensor that detects the presence and magnitude of a magnetic field, helping stop stick drift in controllers.

The Hall Effect is the ratio of the induced electric field to the product of the current density and the applied magnetic field. The output voltage of a Hall sensor is directly proportional to the strength of the field.

The Hall Effect is named after the person who discovered the phenomenon, a man named Edwin Hall, who was studying for his doctorate at Johns Hopkins University in 1879 when he made his discovery.

His findings were regarding the interaction between magnets and electric current, specifically that a voltage difference was generated across a conductor when placed in a perpendicular magnetic field.

Hall’s discovery could not be taken full advantage of until the invention of silicon computer chips many years later, when it was found that the Hall effect could be used in a range of sensors, switches, and transducers, among other components.

Most importantly, since the Hall Effect relies on a magnetic field, none of the components make physical contact, thus eliminating any source of wear and tear and preventing drift.

Remarkably, the Hall Effect has been used before in controllers. Specifically, in the SEGA Saturn 3D controller and the SEGA Dreamcast, which both used Hall Effect sensors for their analog sticks.

It can be a little strange to use a Dreamcast controller now since it is remarkably sensitive and not plagued by Drift, nor by the ‘dead zone’ common in most modern controllers. This dead zone is a feature deliberately added to controllers to minimize the effect of drift.

Why don’t more controllers have Hall Effect sensors?

Hall Effect sensors are more expensive than potentiometers, and up until very recently, they took up much more space than the equivalent potentiometer. It is pretty common to hear the Dreamcast controller criticized for its size, but that size was partially what allowed the Hall Effect sensors to be used.

Are there any controllers that use Hall Effect sensors?

It is becoming more common to see the Hall Effect advertised as a feature, particularly in premium third-party controllers. The 8BitDo Ultimate Controller includes Hall effect analog sticks, for instance, as does the Ayaneo Air, though consumers will find they are paying a premium price for the privilege. Alternatively, for those who are confident with tools it is possible to get Hall Effect upgrade kits from companies such as GuilKit.

Until Hall Effect analog sticks become the standard, users will still be paying a premium to defeat the notorious joystick drift.

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