Remarks
LinearHallEffectTachometer | |
---|---|
Status | Not Tested |
Source code | GitHub |
NuGet package |
A Hall effect sensor is a device that is used to measure the magnitude of a magnetic field. Its output voltage is directly proportional to the magnetic field strength through it. These sensors are commonly used for proximity sensing, positioning, speed detection, and current sensing applications.
Frequently, a Hall sensor is combined with threshold detection so that it acts as and is called a switch. Commonly seen in industrial applications such as the pictured pneumatic cylinder, they are also used in consumer equipment; for example some computer printers use them to detect missing paper and open covers. They can also be used in computer keyboards, an application that requires ultra-high reliability.
Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal combustion engine ignition timing, tachometers and anti-lock braking systems. They are used in brushless DC electric motors to detect the position of the permanent magnet. In the pictured wheel with two equally spaced magnets, the voltage from the sensor will peak twice for each revolution. This arrangement is commonly used to regulate the speed of disk drives.
The following example instantiates a LinearHallEffectTachometer object, and registers the RPMsChanged event handler, and it outputs the RPMs in the output console. To trigger the event of the sensor, you can place a magnet on a rotating object like a small motor, or even a fidget spinner, and make sure that the magnet passes very close to the sensor in every rotation so it picks up the electromagnetic field and it will start measuring RPMs.
Code Example
The following example prints horizontal and vertical values ranging from -1 to 1, 0 being the center position:
public class MeadowApp : App<F7Micro, MeadowApp>
{
public MeadowApp()
{
LinearHallEffectTachometer hallSensor;
public MeadowApp()
{
Console.Write("Initializing...");
hallSensor = new LinearHallEffectTachometer(
inputPort: Device.CreateDigitalInputPort(Device.Pins.D02, Meadow.Hardware.InterruptMode.EdgeRising, Meadow.Hardware.ResistorMode.InternalPullUp, 0, 10),
type: CircuitTerminationType.CommonGround,
numberOfMagnets: 2,
rpmChangeNotificationThreshold: 1);
hallSensor.RPMsChanged += HallSensorRPMsChanged;
Console.WriteLine("done");
}
void HallSensorRPMsChanged(object sender, ChangeResult<float> e)
{
Console.WriteLine($"RPM: {e.New}");
}
}
}
Sample projects available on GitHub
Wiring Example
Characteristic | Locus |
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Inheritance | System.Object > LinearHallEffectTachometer |
Namespace | Meadow.Foundation.Sensors.HallEffect |
Assembly | Meadow.Foundation.dll |
Syntax
public class LinearHallEffectTachometer : object
Constructors
LinearHallEffectTachometer(IDigitalInputController, IPin, CircuitTerminationType, UInt16, Single)
LinearHallEffectTachometer driver
Declaration
public LinearHallEffectTachometer(IDigitalInputController device, IPin inputPin, CircuitTerminationType type = CircuitTerminationType.CommonGround, ushort numberOfMagnets = null, float rpmChangeNotificationThreshold = 1F)
Parameters
Type | Name | Description |
---|---|---|
IDigitalInputController | device | IDigitalInputController to create digital input port |
IPin | inputPin | |
CircuitTerminationType | type | |
System.UInt16 | numberOfMagnets | |
System.Single | rpmChangeNotificationThreshold |
LinearHallEffectTachometer(IDigitalInputPort, CircuitTerminationType, UInt16, Single)
LinearHallEffectTachometer driver
Declaration
public LinearHallEffectTachometer(IDigitalInputPort inputPort, CircuitTerminationType type = CircuitTerminationType.CommonGround, ushort numberOfMagnets = null, float rpmChangeNotificationThreshold = 1F)
Parameters
Type | Name | Description |
---|---|---|
IDigitalInputPort | inputPort | |
CircuitTerminationType | type | |
System.UInt16 | numberOfMagnets | |
System.Single | rpmChangeNotificationThreshold |
Fields
lastNotifiedRPMs
Last notified RPM value
Declaration
protected float lastNotifiedRPMs
Field Value
Type | Description |
---|---|
System.Single |
numberOfReads
Number of reads
Declaration
protected ushort numberOfReads
Field Value
Type | Description |
---|---|
System.UInt16 |
revolutionTimeStart
Revolution start time
Declaration
protected DateTime revolutionTimeStart
Field Value
Type | Description |
---|---|
DateTime |
rpms
Revolutions pers minute
Declaration
protected float rpms
Field Value
Type | Description |
---|---|
System.Single |
Properties
InputPort
Input port for the tachometer
Declaration
protected IDigitalInputPort InputPort { get; set; }
Property Value
Type | Description |
---|---|
IDigitalInputPort |
NumberOfMagnets
Returns number of magnets of the sensor.
Declaration
public ushort NumberOfMagnets { get; }
Property Value
Type | Description |
---|---|
System.UInt16 |
RPMChangeNotificationThreshold
Any changes to the RPMs that are greater than the RPM change threshold will cause an event to be raised when the instance is set to update automatically.
Declaration
public float RPMChangeNotificationThreshold { get; set; }
Property Value
Type | Description |
---|---|
System.Single |
RPMs
Returns number of revolutions per minute.
Declaration
public int RPMs { get; }
Property Value
Type | Description |
---|---|
System.Int32 |
Methods
OnRaiseRPMChanged()
Notify when RPMs change
Declaration
protected void OnRaiseRPMChanged()
Events
RPMsChanged
Event raised when the RPM change is greater than the RPMChangeNotificationThreshold value.
Declaration
public event EventHandler<ChangeResult<float>> RPMsChanged
Event Type
Type | Description |
---|---|
EventHandler<ChangeResult<System.Single>> |