Visual Basic .NET - Hall Effect Bricklet – Tinkerforge

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# Visual Basic .NET - Hall Effect Bricklet

This is the description of the Visual Basic .NET API bindings for the Hall Effect Bricklet. General information and technical specifications for the Hall Effect Bricklet are summarized in its hardware description.

An installation guide for the Visual Basic .NET API bindings is part of their general description.

## Examples

The example code below is Public Domain (CC0 1.0).

### Simple

Download (ExampleSimple.vb)

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    Imports Tinkerforge

    Module ExampleSimple
        Const HOST As String = "localhost"
        Const PORT As Integer = 4223
        Const UID As String = "XYZ" ' Change to your UID

        Sub Main()
            Dim ipcon As New IPConnection() ' Create IP connection
            Dim he As New BrickletHallEffect(UID, ipcon) ' Create device object

            ipcon.Connect(HOST, PORT) ' Connect to brickd
            ' Don't use device before ipcon is connected

            ' Get current edge_count of Hall Effect Bricklet without reset
            Dim edge_count As Long = he.GetEdgeCount(false)

            System.Console.WriteLine("EdgeCount: " + edge_count.ToString())

            System.Console.WriteLine("Press key to exit")
            System.Console.ReadLine()
            ipcon.Disconnect()
        End Sub
    End Module

### Callback

Download (ExampleCallback.vb)

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    Imports Tinkerforge

    Module ExampleCallback
        Const HOST As String = "localhost"
        Const PORT As Integer = 4223
        Const UID As String = "XYZ" ' Change to your UID

        ' Callback function for edge_count callback
        Sub EdgeCountCB(ByVal sender As BrickletHallEffect, ByVal edge_count As Long, ByVal value As Boolean)
            System.Console.WriteLine("Edge Count: " + edge_count.ToString())
        End Sub

        Sub Main()
            Dim ipcon As New IPConnection() ' Create IP connection
            Dim he As New BrickletHallEffect(UID, ipcon) ' Create device object

            ipcon.Connect(HOST, PORT) ' Connect to brickd
            ' Don't use device before ipcon is connected

            ' Set Period for edge_count callback to 0.05s (50ms)
            ' Note: The edge_count callback is only called every 50ms if the
            '       edge_count has changed since the last call!
            he.SetEdgeCountCallbackPeriod(50)

            ' Register edge count callback to EdgeCountCB
            AddHandler he.EdgeCount, AddressOf EdgeCountCB

            System.Console.WriteLine("Press key to exit")
            System.Console.ReadLine()
            ipcon.Disconnect()
        End Sub
    End Module

## API

Since Visual Basic .NET does not support multiple return values directly, we use the `ByRef` keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

### Basic Functions

Class `BrickletHallEffect`(ByVal uid As String, ByVal ipcon As IPConnection)

  Creates an object with the unique device ID `uid`:

      Dim hallEffect As New BrickletHallEffect("YOUR_DEVICE_UID", ipcon)

  This object can then be used after the IP Connection is connected (see examples above).

Function `BrickletHallEffect.``GetValue`() As Boolean

  Returns true if a magnetic field of 35 Gauss (3.5mT) or greater is detected.

Function `BrickletHallEffect.``GetEdgeCount`(ByVal resetCounter As Boolean) As Long

  Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with `SetEdgeCountConfig()`.

  If you set the reset counter to true, the count is set back to 0 directly after it is read.

### Advanced Functions

Sub `BrickletHallEffect.``SetEdgeCountConfig`(ByVal edgeType As Byte, ByVal debounce As Byte)

  The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:

  - 0 = rising (default)
  - 1 = falling
  - 2 = both

  A magnetic field of 35 Gauss (3.5mT) or greater causes a falling edge and a magnetic field of 25 Gauss (2.5mT) or smaller causes a rising edge.

  If a magnet comes near the Bricklet the signal goes low (falling edge), if a magnet is removed from the vicinity the signal goes high (rising edge).

  The debounce time is given in ms.

  Configuring an edge counter resets its value to 0.

  If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

  Default values: 0 (edge type) and 100ms (debounce time)

  The following constants are available for this function:

  - BrickletHallEffect.EDGE_TYPE_RISING = 0
  - BrickletHallEffect.EDGE_TYPE_FALLING = 1
  - BrickletHallEffect.EDGE_TYPE_BOTH = 2

Sub `BrickletHallEffect.``GetEdgeCountConfig`(ByRef edgeType As Byte, ByRef debounce As Byte)

  Returns the edge type and debounce time as set by `SetEdgeCountConfig()`.

  The following constants are available for this function:

  - BrickletHallEffect.EDGE_TYPE_RISING = 0
  - BrickletHallEffect.EDGE_TYPE_FALLING = 1
  - BrickletHallEffect.EDGE_TYPE_BOTH = 2

Function `BrickletHallEffect.``GetAPIVersion`() As Byte()

  Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

Function `BrickletHallEffect.``GetResponseExpected`(ByVal functionId As Byte) As Boolean

  Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

  For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by `SetResponseExpected()`. For setter functions it is disabled by default and can be enabled.

  Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

  See `SetResponseExpected()` for the list of function ID constants available for this function.

Sub `BrickletHallEffect.``SetResponseExpected`(ByVal functionId As Byte, ByVal responseExpected As Boolean)

  Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled and callbacks it is always disabled.

  Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

  The following function ID constants are available for this function:

  - BrickletHallEffect.FUNCTION_SET_EDGE_COUNT_CONFIG = 3
  - BrickletHallEffect.FUNCTION_SET_EDGE_INTERRUPT = 5
  - BrickletHallEffect.FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7

Sub `BrickletHallEffect.``SetResponseExpectedAll`(ByVal responseExpected As Boolean)

  Changes the response expected flag for all setter and callback configuration functions of this device at once.

Sub `BrickletHallEffect.``GetIdentity`(ByRef uid As String, ByRef connectedUid As String, ByRef position As Char, ByRef hardwareVersion() As Byte, ByRef firmwareVersion() As Byte, ByRef deviceIdentifier As Integer)

  Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

  The position can be 'a', 'b', 'c' or 'd'.

  The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

### Callback Configuration Functions

Sub `BrickletHallEffect.``SetEdgeInterrupt`(ByVal edges As Long)

  Sets the number of edges until an interrupt is invoked.

  If edges is set to n, an interrupt is invoked for every n-th detected edge.

  If edges is set to 0, the interrupt is disabled.

  Default value is 0.

Function `BrickletHallEffect.``GetEdgeInterrupt`() As Long

  Returns the edges as set by `SetEdgeInterrupt()`.

Sub `BrickletHallEffect.``SetEdgeCountCallbackPeriod`(ByVal period As Long)

  Sets the period in ms with which the `EdgeCount` callback is triggered periodically. A value of 0 turns the callback off.

  `EdgeCount` is only triggered if the edge count has changed since the last triggering.

  The default value is 0.

Function `BrickletHallEffect.``GetEdgeCountCallbackPeriod`() As Long

  Returns the period as set by `SetEdgeCountCallbackPeriod()`.

### Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done by assigning a procedure to an callback property of the device object:

>     Sub Callback(ByVal sender As BrickletHallEffect, ByVal value As Short)
>         Console.WriteLine("Value: {0}", value)
>     End Sub

>     AddHandler hallEffect.Example, AddressOf Callback

The available callback property and their type of parameters are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

Event `BrickletHallEffect.``EdgeCount`(ByVal sender As BrickletHallEffect, ByVal count As Long, ByVal value As Boolean)

  This callback is triggered periodically with the period that is set by `SetEdgeCountCallbackPeriod()`. The parameters are the current count and the current value (see `GetValue()` and `GetEdgeCount()`).

  `EdgeCount` is only triggered if the count or value changed since the last triggering.

### Constants

Const `BrickletHallEffect.``DEVICE_IDENTIFIER`

  This constant is used to identify a Hall Effect Bricklet.

  The `GetIdentity()` function and the `EnumerateCallback` callback of the IP Connection have a `deviceIdentifier` parameter to specify the Brick's or Bricklet's type.

The content of this page is licensed under Creative Commons Attribution 3.0 Unported License.