Mathematica - Multi Touch Bricklet

This is the description of the Mathematica API bindings for the Multi Touch Bricklet. General information and technical specifications for the Multi Touch Bricklet are summarized in its hardware description.

An installation guide for the Mathematica API bindings is part of their general description.

Examples

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

Simple

Download (ExampleSimple.nb)

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Needs["NETLink`"]
LoadNETAssembly["Tinkerforge",NotebookDirectory[]<>"../../.."]

host="localhost"
port=4223
uid="XYZ"(*Change XYZ to the UID of your Multi Touch Bricklet*)

(*Create IPConnection and device object*)
ipcon=NETNew["Tinkerforge.IPConnection"]
mt=NETNew["Tinkerforge.BrickletMultiTouch",uid,ipcon]
ipcon@Connect[host,port]

(*Get current touch state*)
touchStateBits=IntegerDigits[mt@GetTouchState[],2,13]
result={}

If[touchStateBits[[-13]]==1,AppendTo[result,"In proximity, "]]

If[Total[touchStateBits[[2;;13]]]==0,
 AppendTo[result,"No electrodes touched"],
 AppendTo[result,"Electrodes "];
 For[i=-1,i>=-12,--i,
  If[touchStateBits[[i]]==1,AppendTo[result,ToString[Abs[i]-1]<>" "]]
 ];
 AppendTo[result,"touched"]
]

Print[StringJoin[result]]

(*Clean up*)
ipcon@Disconnect[]
ReleaseNETObject[mt]
ReleaseNETObject[ipcon]

Callback

Download (ExampleCallback.nb)

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Needs["NETLink`"]
LoadNETAssembly["Tinkerforge",NotebookDirectory[]<>"../../.."]

host="localhost"
port=4223
uid="XYZ"(*Change XYZ to the UID of your Multi Touch Bricklet*)

(*Create IPConnection and device object*)
ipcon=NETNew["Tinkerforge.IPConnection"]
mt=NETNew["Tinkerforge.BrickletMultiTouch",uid,ipcon]
ipcon@Connect[host,port]

(*Callback function for touch state callback*)
TouchStateCB[sender_,state_]:=
 Module[{},
  touchStateBits=IntegerDigits[touchState,2,13];
  result={};
  If[touchStateBits[[-13]]==1,AppendTo[result,"In proximity, "]];
  If[Total[touchStateBits[[2;;13]]]==0,
   AppendTo[result,"No electrodes touched"],
   AppendTo[result,"Electrodes "];
   For[i=-1,i>=-12,--i,
    If[touchStateBits[[i]]==1,AppendTo[result,ToString[Abs[i]-1]<>" "]]
   ];
   AppendTo[result,"touched"]
  ];
  Print[StringJoin[result]]
 ]

AddEventHandler[mt@TouchStateCallback,TouchStateCB]

Input["Click OK to exit"]

(*Clean up*)
ipcon@Disconnect[]
ReleaseNETObject[mt]
ReleaseNETObject[ipcon]

API

Generally, every method of the Mathematica bindings that returns a value can throw a Tinkerforge.TimeoutException. This exception gets thrown if the device did not respond. If a cable based connection is used, it is unlikely that this exception gets thrown (assuming nobody plugs the device out). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Since .NET/Link does not support multiple return values directly, we use the out keyword to return multiple values from a method. For further information about the out keyword in .NET/Link see the corresponding Mathematica .NET/Link documentation.

The namespace for all Brick/Bricklet bindings and the IPConnection is Tinkerforge.*.

Basic Functions

BrickletMultiTouch[uid, ipcon] → multiTouch
Parameters:
  • uid -- String
  • ipcon -- NETObject[IPConnection]
Returns:
  • multiTouch -- NETObject[BrickletMultiTouch]

Creates an object with the unique device ID uid:

multiTouch=NETNew["Tinkerforge.BrickletMultiTouch","YOUR_DEVICE_UID",ipcon]

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

The .NET runtime has built-in garbage collection that frees objects that are no longer in use by a program. But because Mathematica can not automatically tell when a Mathematica "program" doesn't use a .NET object anymore, this has to be done by the program. For this the ReleaseNETObject[] function is used in the examples.

For further information about object management in .NET/Link see the corresponding Mathematica .NET/Link documentation.

BrickletMultiTouch@GetTouchState[] → state
Returns:
  • state -- Integer

Returns the current touch state. The state is given as a bitfield.

Bits 0 to 11 represent the 12 electrodes and bit 12 represents the proximity.

If an electrode is touched, the corresponding bit is true. If a hand or similar is in proximity to the electrodes, bit 12 is true.

Example: The state 4103 = 0x1007 = 0b1000000000111 means that electrodes 0, 1 and 2 are touched and that something is in the proximity of the electrodes.

The proximity is activated with a distance of 1-2cm. An electrode is already counted as touched if a finger is nearly touching the electrode. This means that you can put a piece of paper or foil or similar on top of a electrode to build a touch panel with a professional look.

BrickletMultiTouch@Recalibrate[] → Null

Recalibrates the electrodes. Call this function whenever you changed or moved you electrodes.

BrickletMultiTouch@SetElectrodeConfig[enabledElectrodes] → Null
Parameters:
  • enabledElectrodes -- Integer

Enables/disables electrodes with a bitfield (see GetTouchState[]).

True enables the electrode, false disables the electrode. A disabled electrode will always return false as its state. If you don't need all electrodes you can disable the electrodes that are not needed.

It is recommended that you disable the proximity bit (bit 12) if the proximity feature is not needed. This will reduce the amount of traffic that is produced by the TouchStateCallback callback.

Disabling electrodes will also reduce power consumption.

Default: 8191 = 0x1FFF = 0b1111111111111 (all electrodes enabled)

BrickletMultiTouch@GetElectrodeConfig[] → enabledElectrodes
Returns:
  • enabledElectrodes -- Integer

Returns the electrode configuration, as set by SetElectrodeConfig[].

BrickletMultiTouch@SetElectrodeSensitivity[sensitivity] → Null
Parameters:
  • sensitivity -- Integer

Sets the sensitivity of the electrodes. An electrode with a high sensitivity will register a touch earlier then an electrode with a low sensitivity.

If you build a big electrode you might need to decrease the sensitivity, since the area that can be charged will get bigger. If you want to be able to activate an electrode from further away you need to increase the sensitivity.

After a new sensitivity is set, you likely want to call Recalibrate[] to calibrate the electrodes with the newly defined sensitivity.

The valid sensitivity value range is 5-201.

The default sensitivity value is 181.

BrickletMultiTouch@GetElectrodeSensitivity[] → sensitivity
Returns:
  • sensitivity -- Integer

Returns the current sensitivity, as set by SetElectrodeSensitivity[].

Advanced Functions

BrickletMultiTouch@GetAPIVersion[] → {apiVersion1, apiVersion2, apiVersion3}
Returns:
  • apiVersioni -- Integer

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.

BrickletMultiTouch@GetResponseExpected[functionId] → responseExpected
Parameters:
  • functionId -- Integer
Returns:
  • responseExpected -- True/False

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.

BrickletMultiTouch@SetResponseExpected[functionId, responseExpected] → Null
Parameters:
  • functionId -- Integer
  • responseExpected -- True/False

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.

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:

  • BrickletMultiTouch`FUNCTIONURECALIBRATE = 2
  • BrickletMultiTouch`FUNCTIONUSETUELECTRODEUCONFIG = 3
  • BrickletMultiTouch`FUNCTIONUSETUELECTRODEUSENSITIVITY = 6
BrickletMultiTouch@SetResponseExpectedAll[responseExpected] → Null
Parameters:
  • responseExpected -- True/False

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

BrickletMultiTouch@GetIdentity[out uid, out connectedUid, out position, out {hardwareVersion1, hardwareVersion2, hardwareVersion3}, out {firmwareVersion1, firmwareVersion2, firmwareVersion3}, out deviceIdentifier] → Null
Parameters:
  • uid -- String
  • connectedUid -- String
  • position -- Integer
  • hardwareVersioni -- Integer
  • firmwareVersioni -- Integer
  • deviceIdentifier -- 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.

Callbacks

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

MyCallback[sender_,value_]:=Print["Value: "<>ToString[value]]

AddEventHandler[multiTouch@ExampleCallback,MyCallback]

For further information about event handling using .NET/Link see the corresponding Mathematica .NET/Link documentation.

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 BrickletMultiTouch@TouchStateCallback[sender, state]
Parameters:
  • sender -- NETObject[BrickletMultiTouch]
  • state -- Integer

Returns the current touch state, see GetTouchState[] for information about the state.

This callback is triggered every time the touch state changes.

Constants

BrickletMultiTouch`DEVICEUIDENTIFIER

This constant is used to identify a Multi Touch 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.

BrickletMultiTouch`DEVICEDISPLAYNAME

This constant represents the human readable name of a Multi Touch Bricklet.