Visual Basic .NET - Gas Detector Bricklet

Note

This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.

This is the description of the Visual Basic .NET API bindings for the Gas Detector Bricklet. General information and technical specifications for the Gas Detector 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).

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 BrickletGasDetector(ByVal uid As String, ByVal ipcon As IPConnection)

Creates an object with the unique device ID uid:

Dim gasDetector As New BrickletGasDetector("YOUR_DEVICE_UID", ipcon)

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

Function BrickletGasDetector.GetValue() As Integer

Returns a value between 0 and 4095.

See here for more information about the measurements.

If you want to get the value periodically, it is recommended to use the callback Value and set the period with SetValueCallbackPeriod().

Advanced Functions

Sub BrickletGasDetector.SetMovingAverage(ByVal average As Byte)

Sets the length of a moving averaging for the measured value.

Setting the length to 1 will turn the averaging off. With less averaging, there is more noise on the data.

The range for the averaging is 1-100.

The default value is 100.

Function BrickletGasDetector.GetMovingAverage() As Byte

Returns the length moving average as set by SetMovingAverage().

Sub BrickletGasDetector.SetDetectorType(ByVal detectorType As Byte)

Sets the detector type.

The following types are currently supported.

  • Type 0: MQ2 and MQ5
  • Type 1: MQ3

The detector type is written to the EEPROM of the Bricklet, so it only has to be set once.

You can use the Brick Viewer to set the detector type, so you likely don't need to use this function in your source code.

The default detector type is 0.

The following constants are available for this function:

  • BrickletGasDetector.DETECTOR_TYPE_0 = 0
  • BrickletGasDetector.DETECTOR_TYPE_1 = 1
Function BrickletGasDetector.GetDetectorType() As Byte

Returns the detector type as set by SetDetectorType().

The following constants are available for this function:

  • BrickletGasDetector.DETECTOR_TYPE_0 = 0
  • BrickletGasDetector.DETECTOR_TYPE_1 = 1
Sub BrickletGasDetector.HeaterOn()

Turns the internal heater on.

Sub BrickletGasDetector.HeaterOff()

Turns the internal heater off.

Function BrickletGasDetector.IsHeaterOn() As Boolean

Returns true if the heater is on, false otherwise.

Function BrickletGasDetector.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 BrickletGasDetector.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 BrickletGasDetector.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:

  • BrickletGasDetector.FUNCTION_SET_VALUE_CALLBACK_PERIOD = 2
  • BrickletGasDetector.FUNCTION_SET_VALUE_CALLBACK_THRESHOLD = 4
  • BrickletGasDetector.FUNCTION_SET_DEBOUNCE_PERIOD = 6
  • BrickletGasDetector.FUNCTION_SET_MOVING_AVERAGE = 8
  • BrickletGasDetector.FUNCTION_SET_DETECTOR_TYPE = 10
  • BrickletGasDetector.FUNCTION_HEATER_ON = 12
  • BrickletGasDetector.FUNCTION_HEATER_OFF = 13
Sub BrickletGasDetector.SetResponseExpectedAll(ByVal responseExpected As Boolean)

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

Sub BrickletGasDetector.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 BrickletGasDetector.SetValueCallbackPeriod(ByVal period As Long)

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

Value is only triggered if the value value has changed since the last triggering.

The default value is 0.

Function BrickletGasDetector.GetValueCallbackPeriod() As Long

Returns the period as set by SetValueCallbackPeriod().

Sub BrickletGasDetector.SetValueCallbackThreshold(ByVal option As Char, ByVal min As Integer, ByVal max As Integer)

Sets the thresholds for the ValueReached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the value value is outside the min and max values
'i' Callback is triggered when the value value is inside the min and max values
'<' Callback is triggered when the value value is smaller than the min value (max is ignored)
'>' Callback is triggered when the value value is greater than the min value (max is ignored)

The default value is ('x', 0, 0).

The following constants are available for this function:

  • BrickletGasDetector.THRESHOLD_OPTION_OFF = "x"C
  • BrickletGasDetector.THRESHOLD_OPTION_OUTSIDE = "o"C
  • BrickletGasDetector.THRESHOLD_OPTION_INSIDE = "i"C
  • BrickletGasDetector.THRESHOLD_OPTION_SMALLER = "<"C
  • BrickletGasDetector.THRESHOLD_OPTION_GREATER = ">"C
Sub BrickletGasDetector.GetValueCallbackThreshold(ByRef option As Char, ByRef min As Integer, ByRef max As Integer)

Returns the threshold as set by SetValueCallbackThreshold().

The following constants are available for this function:

  • BrickletGasDetector.THRESHOLD_OPTION_OFF = "x"C
  • BrickletGasDetector.THRESHOLD_OPTION_OUTSIDE = "o"C
  • BrickletGasDetector.THRESHOLD_OPTION_INSIDE = "i"C
  • BrickletGasDetector.THRESHOLD_OPTION_SMALLER = "<"C
  • BrickletGasDetector.THRESHOLD_OPTION_GREATER = ">"C
Sub BrickletGasDetector.SetDebouncePeriod(ByVal debounce As Long)

Sets the period in ms with which the threshold callback

is triggered, if the threshold

keeps being reached.

The default value is 100.

Function BrickletGasDetector.GetDebouncePeriod() As Long

Returns the debounce period as set by SetDebouncePeriod().

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 BrickletGasDetector, ByVal value As Short)
    Console.WriteLine("Value: {0}", value)
End Sub

AddHandler gasDetector.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 BrickletGasDetector.Value(ByVal sender As BrickletGasDetector, ByVal value As Integer)

This callback is triggered periodically with the period that is set by SetValueCallbackPeriod(). The parameter is the value value of the sensor.

Value is only triggered if the value has changed since the last triggering.

Event BrickletGasDetector.ValueReached(ByVal sender As BrickletGasDetector, ByVal value As Integer)

This callback is triggered when the threshold as set by SetValueCallbackThreshold() is reached. The parameter is the value of the detector.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by SetDebouncePeriod().

Constants

Const BrickletGasDetector.DEVICE_IDENTIFIER

This constant is used to identify a Gas Detector 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.

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