Linear Hall effect Sensor

Working Principle:

In a Hall effect sensor, a thin strip of metal has a current applied along it. In the presence of a magnetic field, the electrons in the metal strip are deflected toward one edge, producing a voltage gradient across the short side of the strip (perpendicular to the feed current). Hall effect sensors have an advantage over inductive sensors in that, while inductive sensors respond to a changing magnetic field which induces current in a coil of wire and produces voltage at its output, Hall effect sensors can detect static (non-changing) magnetic fields.

In its simplest form, the sensor operates as an  analog transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced.

When a beam of charged particles passes through a magnetic field, forces act on the particles and the beam is deflected from a straight path. The flow of electrons through a conductor form a beam of charged carriers. When an conductor is placed in a magnetic field perpendicular to the direction of the electrons, they will be deflected from a straight path. As a consequence, one plane of the conductor will become negatively charged and the opposite side will become positively charged. The voltage between these planes is called the Hall voltage.

When the force on the charged particles from the electric field balances the force produced by the magnetic field, the separation of them will stop. If the current is not changing, then the Hall voltage is a measure of the magnetic flux density. Basically, there are two kinds of Hall effect sensors: linear, which means the output of voltage linearly depends on magnetic flux density; and threshold, which means there will be a sharp decrease of output voltage at each magnetic flux density. This experiment was the one to demonstrate that there are only negative charges free to move in a conductor. Before this, it was believed that positive charges move in a current carrying conductor. This experiment is known as the Hall Experiment.


Pin Configuration:

A0: Analog pin of arduino
GND: ground
positive terminal : +5v
D0: digital pin of arduino



Types of Hall Devices

Based on the orientation and characteristics of the Active Area (Hall Element), Hall Effect Sensors can be categorized into three types.

  • Planar Hall Device
  • Vertical Hall Device
  • 3D Hall Device

In Planar Hall Devices, the flux lines of the magnetic field must pass perpendicularly through the active area to optimally operate the switch. Here, the active area is parallel to the branded face of the IC i.e. the face marked with Manufacturer part number.



Interfacing with Arduino



const int ledPin = 10;
const int hallPin = 2;
volatile bool ledState = LOW;
void setup()
attachInterrupt(digitalPinToInterrupt(hallPin), hall_ISR, CHANGE);
void loop()
digitalWrite(ledPin, ledState);
void hall_ISR()
ledState = !ledState;