Mathematica - Load Cell Bricklet – Tinkerforge

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# Mathematica - Load Cell 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 Mathematica API bindings for the Load Cell Bricklet. General information and technical specifications for the Load Cell 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="amb"(* Change to your UID *)

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

    (* Get current weight (unit is g) *)
    Print["Weight: "<>ToString[N[Quantity[lc@GetWeight[],"g"]]]]

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

### Callback

Download (ExampleCallback.nb)

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

    host="localhost"
    port=4223
    uid="amb"(* Change to your UID *)

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

    (* Set Period for weight callback to 1s (1000ms) *)
    (* Note: The weight callback is only called every second if the *)
    (*       weight has changed since the last call! *)
    lc@SetWeightCallbackPeriod[1000]

    (* Callback function for weight callback (parameter has unit g) *)
    WeightCB[sender_,weight_]:=
     Print["Weight: "<>ToString[N[Quantity[weight,"g"]]]]
    AddEventHandler[lc@Weight,WeightCB]

    Input["Click OK to exit"]

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

### Threshold

Download (ExampleThreshold.nb)

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

    host="localhost"
    port=4223
    uid="amb"(* Change to your UID *)

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

    (* Get threshold callbacks with a debounce time of 10 seconds (10000ms) *)
    lc@SetDebouncePeriod[10000]

    (* Callback for weight greater than 200 g *)
    WeightReachedCB[sender_,weight_]:=
     Module[{},
      Print["Weight: "<>ToString[N[Quantity[weight,"g"]]]<>"."];
     ]

    AddEventHandler[lc@WeightReached,WeightReachedCB]

    (* Configure threshold for "greater than 200 g" *)
    option=Tinkerforge`BrickletLoadCell`THRESHOLDUOPTIONUGREATER
    lc@SetWeightCallbackThreshold[option,200,0]

    Input["Click OK to exit"]

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

`BrickletLoadCell`[uid, ipcon] → loadCell

  Parameters:

  - uid -- String
  - ipcon -- NETObject[IPConnection]

  Returns:

  - loadCell -- NETObject[BrickletLoadCell]

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

      loadCell=NETNew["Tinkerforge.BrickletLoadCell","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.

`BrickletLoadCell``@``GetWeight`[] → weight

  Returns:

  - weight -- Integer

  Returns the currently measured weight in grams.

  If you want to get the weight periodically, it is recommended to use the callback `Weight` and set the period with `SetWeightCallbackPeriod[]`.

`BrickletLoadCell``@``LEDOn`[] → Null

  Turns the LED on.

`BrickletLoadCell``@``LEDOff`[] → Null

  Turns the LED off.

`BrickletLoadCell``@``IsLEDOn`[] → value

  Returns:

  - value -- Integer

  Returns true if the led is on, false otherwise.

`BrickletLoadCell``@``Tare`[] → Null

  Sets the currently measured weight as tare weight.

### Advanced Functions

`BrickletLoadCell``@``SetMovingAverage`[average] → Null

  Parameters:

  - average -- Integer

  Sets the length of a moving averaging for the weight 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 1-40.

  The default value is 4.

`BrickletLoadCell``@``GetMovingAverage`[] → average

  Returns:

  - average -- Integer

  Returns the length moving average as set by `SetMovingAverage[]`.

`BrickletLoadCell``@``Calibrate`[weight] → Null

  Parameters:

  - weight -- Integer

  To calibrate your Load Cell Bricklet you have to

  - empty the scale and call this function with 0 and
  - add a known weight to the scale and call this function with the weight in grams.

  The calibration is saved in the EEPROM of the Bricklet and only needs to be done once.

  We recommend to use the Brick Viewer for calibration, you don't need to call this function in your source code.

`BrickletLoadCell``@``SetConfiguration`[rate, gain] → Null

  Parameters:

  - rate -- Integer
  - gain -- Integer

  The measurement rate and gain are configurable.

  The rate can be either 10Hz or 80Hz. A faster rate will produce more noise. It is additionally possible to add a moving average (see `SetMovingAverage[]`) to the measurements.

  The gain can be 128x, 64x or 32x. It represents a measurement range of ±20mV, ±40mV and ±80mV respectively. The Load Cell Bricklet uses an excitation voltage of 5V and most load cells use an output of 2mV/V. That means the voltage range is ±15mV for most load cells (i.e. gain of 128x is best). If you don't know what all of this means you should keep it at 128x, it will most likely be correct.

  The configuration is saved in the EEPROM of the Bricklet and only needs to be done once.

  We recommend to use the Brick Viewer for configuration, you don't need to call this function in your source code.

  The default rate is 10Hz and the default gain is 128x.

  The following constants are available for this function:

  - BrickletLoadCell`RATEU10HZ = 0
  - BrickletLoadCell`RATEU80HZ = 1
  - BrickletLoadCell`GAINU128X = 0
  - BrickletLoadCell`GAINU64X = 1
  - BrickletLoadCell`GAINU32X = 2

`BrickletLoadCell``@``GetConfiguration`[out rate, out gain] → Null

  Parameters:

  - rate -- Integer
  - gain -- Integer

  Returns the configuration as set by `SetConfiguration[]`.

  The following constants are available for this function:

  - BrickletLoadCell`RATEU10HZ = 0
  - BrickletLoadCell`RATEU80HZ = 1
  - BrickletLoadCell`GAINU128X = 0
  - BrickletLoadCell`GAINU64X = 1
  - BrickletLoadCell`GAINU32X = 2

`BrickletLoadCell``@``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.

`BrickletLoadCell``@``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.

`BrickletLoadCell``@``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 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:

  - BrickletLoadCell`FUNCTIONUSETUWEIGHTUCALLBACKUPERIOD = 2
  - BrickletLoadCell`FUNCTIONUSETUWEIGHTUCALLBACKUTHRESHOLD = 4
  - BrickletLoadCell`FUNCTIONUSETUDEBOUNCEUPERIOD = 6
  - BrickletLoadCell`FUNCTIONUSETUMOVINGUAVERAGE = 8
  - BrickletLoadCell`FUNCTIONULEDUON = 10
  - BrickletLoadCell`FUNCTIONULEDUOFF = 11
  - BrickletLoadCell`FUNCTIONUCALIBRATE = 13
  - BrickletLoadCell`FUNCTIONUTARE = 14
  - BrickletLoadCell`FUNCTIONUSETUCONFIGURATION = 15

`BrickletLoadCell``@``SetResponseExpectedAll`[responseExpected] → Null

  Parameters:

  - responseExpected -- True/False

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

`BrickletLoadCell``@``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.

### Callback Configuration Functions

`BrickletLoadCell``@``SetWeightCallbackPeriod`[period] → Null

  Parameters:

  - period -- Integer

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

  `Weight` is only triggered if the weight has changed since the last triggering.

  The default value is 0.

`BrickletLoadCell``@``GetWeightCallbackPeriod`[] → period

  Returns:

  - period -- Integer

  Returns the period as set by `SetWeightCallbackPeriod[]`.

`BrickletLoadCell``@``SetWeightCallbackThreshold`[option, min, max] → Null

  Parameters:

  - option -- Integer
  - min -- Integer
  - max -- Integer

  Sets the thresholds for the `WeightReached` callback.

  The following options are possible:

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

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

  The following constants are available for this function:

  - BrickletLoadCell`THRESHOLDUOPTIONUOFF = `ToCharacterCode["x"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUOUTSIDE = `ToCharacterCode["o"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUINSIDE = `ToCharacterCode["i"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUSMALLER = `ToCharacterCode["<"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUGREATER = `ToCharacterCode[">"][[0]]`

`BrickletLoadCell``@``GetWeightCallbackThreshold`[out option, out min, out max] → Null

  Parameters:

  - option -- Integer
  - min -- Integer
  - max -- Integer

  Returns the threshold as set by `SetWeightCallbackThreshold[]`.

  The following constants are available for this function:

  - BrickletLoadCell`THRESHOLDUOPTIONUOFF = `ToCharacterCode["x"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUOUTSIDE = `ToCharacterCode["o"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUINSIDE = `ToCharacterCode["i"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUSMALLER = `ToCharacterCode["<"][[0]]`
  - BrickletLoadCell`THRESHOLDUOPTIONUGREATER = `ToCharacterCode[">"][[0]]`

`BrickletLoadCell``@``SetDebouncePeriod`[debounce] → Null

  Parameters:

  - debounce -- Integer

  Sets the period in ms with which the threshold callback

  - `WeightReached`

  is triggered, if the threshold

  - `SetWeightCallbackThreshold[]`

  keeps being reached.

  The default value is 100.

`BrickletLoadCell``@``GetDebouncePeriod`[] → debounce

  Returns:

  - debounce -- Integer

  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 function to a callback property of the device object:

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

>     AddEventHandler[loadCell@Example,Callback]

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 `BrickletLoadCell``@``Weight`[sender, weight]

  Parameters:

  - sender -- NETObject[BrickletLoadCell]
  - weight -- Integer

  This callback is triggered periodically with the period that is set by `SetWeightCallbackPeriod[]`. The parameter is the weight as measured by the load cell.

  `Weight` is only triggered if the weight has changed since the last triggering.

event `BrickletLoadCell``@``WeightReached`[sender, weight]

  Parameters:

  - sender -- NETObject[BrickletLoadCell]
  - weight -- Integer

  This callback is triggered when the threshold as set by `SetWeightCallbackThreshold[]` is reached. The parameter is the weight as measured by the load cell.

  If the threshold keeps being reached, the callback is triggered periodically with the period as set by `SetDebouncePeriod[]`.

### Constants

`BrickletLoadCell`````DEVICEUIDENTIFIER`

  This constant is used to identify a Load Cell 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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