Hall-Effect Sensor Digital 3144

The 3144 sensor can detect the presence of a magnetic field and a output logic level.

DESCRIPTION

The Hall-Effect Sensor Digital 3144 can detect the the presence or absence of a magnetic field and outputs a logic level.

PACKAGE INCLUDES:

• Hall-Effect Sensor Digital 3144

KEY FEATURES OF HALL-EFFECT SENSOR ANALOG 3144:

• Senses presence or absence of magnetic field and provides logic level output
• Operates over range of 4.5-24V (5V compatible)

Hall-effect sensors are commonly used for measuring the speed of rotating assemblies where a magnet on the assembly alternately makes and breaks magnetic contact with the sensor as the assembly rotates.  They can also be used for applications such as determining when a door has been opened, position sensing and detecting the magnetic field created by current flow in a wire.

The 3144 sensor can detect the basic presence of the magnetic field, but not the relative strength.  The side of the sensor with the labeling is the side used for detection and detects the one pole of the magnet.  The other side of the device will detect the other pole of the magnet.  If the sensor does not seem to be detecting the magnet, try reversing it.

Hall-effect sensors have several advantages over mechanic switches, chief among them are that by being solid-state, there is no concern about contacts wearing out and the switching speed can be quite high, as fast as 2uS.

The main challenge with using Hall-effect sensors usually resides around the mounting of the sensor and any associated magnets.

Power Supply

The sensor can operate over a Vcc range of 4.5-24V.

If the output is being read by an MCU, it is advisable to operate the sensor at the same voltage as the MCU so that the sensor output will be compatible with the digital input on the MCU

It is possible to power the device off a 5V MCU digital output pin.

Digital Output

The sensor output is open collector.  A pull-up resistor of about 10K is normally used to pull the output high.  This can be an external resistor or can be a built-in pull-up resistor on the MCU input.  When a magnetic field is detected, the sensor pulls the output LOW.

When the sensor output goes LOW, it can sink up to 25mA of current.

The output is typically read by a digital pin on an MCU.  Optionally in some cases it may be able to drive a secondary circuit directly.

OUR EVALUATION RESULTS:

Hall-effect sensors are quite useful in a number of applications and one of the more under utilized electronic components available to hobbyists.  These particular sensors are used in many of the digital hall effect sensor modules that come out of China.

The program below monitors the output of the sensor and reports when it detects a state change.  Simply hook the sensor up to 5V and ground and connect the sensor output pin to a digital pin on the MCU.  We use pin D4 in this example but this can be any digital input pin.

After downloading, open the Serial Monitor window to see the output.  If the state does not change when the magnet is brought near, try reversing the magnet (swap north & south ends).

Digital Hall-effect Sensor Example Program

/*
Digital Hall Effect Module Test

Basic code for monitoring the output of the sensor.  
Connect Output pin of sensor to D4 and connect 5V and Ground 
*/
int sensorPin = 4; // Arbitrary digital pin for monitoring the output
int state = 0;    // Current state of the sensor
int lastState = 0;  //Place to save our previous state
//===============================================================================
//  Initialization
//===============================================================================
void setup() 
{ 
  pinMode (sensorPin, INPUT_PULLUP); // Enable pull-up as sensor output is open collector
  Serial.begin (9600);      // Set output window comm rate
}

//===============================================================================
//  Main
//===============================================================================
void loop() 
{
  state = digitalRead (sensorPin);    // Read the current state of the sensor
  if (state != lastState)             // State has changed, so print out new state
  {
    Serial.print ("Current State: ");
    Serial.println (state);
   lastState = state;                 // Remember last state we were in
  }
}

BEFORE THEY ARE SHIPPED, THESE SENSORS ARE:

• Sample tested per incoming shipment
• Packaged in a resealable ESD bag for protection and easy storage.

Notes: 

1. None

TECHNICAL SPECIFICATIONS