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:breadcrumbs: <a href="../../index.html">Home</a> / <a href="../../index.html#software-shell">Software</a> / Shell - Line Bricklet

.. |device_identifier_constant| unicode:: 0xA0
   :trim:

.. _line_bricklet_shell:

Shell - Line Bricklet
=====================

This is the description of the :ref:`Shell API bindings <api_bindings_shell>` for the :ref:`Line Bricklet <line_bricklet>`. General information and technical
specifications for the Line Bricklet are summarized in its :ref:`hardware description
<line_bricklet_description>`.

An :ref:`installation guide <api_bindings_shell_install>` for the Shell API
bindings is part of their general description.

.. _line_bricklet_shell_examples:


Examples
--------

The example code below is `Public Domain (CC0 1.0)
<http://creativecommons.org/publicdomain/zero/1.0/>`__.

Simple
^^^^^^

`Download (example-simple.sh) <https://github.com/Tinkerforge/line-bricklet/raw/master/software/examples/shell/example-simple.sh>`__

.. literalinclude:: Line_Bricklet_Shell_example-simple.sh
 :language: bash
 :linenos:
 :tab-width: 4

Callback
^^^^^^^^

`Download (example-callback.sh) <https://github.com/Tinkerforge/line-bricklet/raw/master/software/examples/shell/example-callback.sh>`__

.. literalinclude:: Line_Bricklet_Shell_example-callback.sh
 :language: bash
 :linenos:
 :tab-width: 4

Threshold
^^^^^^^^^

`Download (example-threshold.sh) <https://github.com/Tinkerforge/line-bricklet/raw/master/software/examples/shell/example-threshold.sh>`__

.. literalinclude:: Line_Bricklet_Shell_example-threshold.sh
 :language: bash
 :linenos:
 :tab-width: 4

.. _line_bricklet_shell_api:

API
---

Possible exit codes for all ``tinkerforge`` commands are:

* 1: interrupted (ctrl+c)
* 2: syntax error
* 21: Python 2.5 or newer is required
* 22: Python ``argparse`` module is missing
* 23: socket error
* 24: other exception
* 25: invalid placeholder in format string
* 26: authentication error
* 201: timeout occurred
* 209: invalid argument value
* 210: function is not supported
* 211: unknown error



Command Structure
^^^^^^^^^^^^^^^^^

The common options of the ``call`` and ``dispatch`` commands are documented
:ref:`here <ipcon_shell_api>`. The specific command structure is shown below.

.. sh:function:: X Stinkerforge Pcall Nline-bricklet A[<option>..] L<uid> L<function> L[<argument>..]

 :param <uid>: string
 :param <function>: string

 The ``call`` command is used to call a function of the Line Bricklet. It can take several
 options:

 * ``--help`` shows help for the specific ``call`` command and exits
 * ``--list-functions`` shows a list of known functions of the Line Bricklet and exits


.. sh:function:: X Stinkerforge Pdispatch Nline-bricklet A[<option>..] L<uid> L<callback>

 :param <uid>: string
 :param <callback>: string

 The ``dispatch`` command is used to dispatch a callback of the Line Bricklet. It can
 take several options:

 * ``--help`` shows help for the specific ``dispatch`` command and exits
 * ``--list-callbacks`` shows a list of known callbacks of the Line Bricklet and exits


.. sh:function:: X Stinkerforge Scall Pline-bricklet L<uid> N<function> A[<option>..] L[<argument>..]

 :param <uid>: string
 :param <function>: string

 The ``<function>`` to be called can take different options depending of its
 kind. All functions can take the following options:

 * ``--help`` shows help for the specific function and exits

 Getter functions can take the following options:

 * ``--execute <command>`` shell command line to execute for each incoming
   response (see section about :ref:`output formatting <ipcon_shell_output>`
   for details)

 Setter functions can take the following options:

 * ``--expect-response`` requests response and waits for it

 The ``--expect-response`` option for setter functions allows to detect
 timeouts and other error conditions calls of setters as well. The device will
 then send a response for this purpose. If this option is not given for a
 setter function then no response is send and errors are silently ignored,
 because they cannot be detected.


.. sh:function:: X Stinkerforge Sdispatch Pline-bricklet L<uid> N<callback> A[<option>..]

 :param <uid>: string
 :param <callback>: string

 The ``<callback>`` to be dispatched can take several options:

 * ``--help`` shows help for the specific callback and exits
 * ``--execute <command>`` shell command line to execute for each incoming
   response (see section about :ref:`output formatting <ipcon_shell_output>`
   for details)



Basic Functions
^^^^^^^^^^^^^^^



.. sh:function:: tinkerforge call line-bricklet <uid> get-reflectivity  


 :returns reflectivity: int

 Returns the currently measured reflectivity. The reflectivity is
 a value between 0 (not reflective) and 4095 (very reflective).
 
 Usually black has a low reflectivity while white has a high
 reflectivity.
 
 If you want to get the reflectivity periodically, it is recommended 
 to use the callback :sh:func:`reflectivity <line-bricklet reflectivity>` and set the period with 
 :sh:func:`set-reflectivity-callback-period <line-bricklet set-reflectivity-callback-period>`.
 


Advanced Functions
^^^^^^^^^^^^^^^^^^

.. sh:function:: tinkerforge call line-bricklet <uid> get-identity  


 :returns uid: string
 :returns connected-uid: string
 :returns position: char
 :returns hardware-version: int,int,int
 :returns firmware-version: int,int,int
 :returns device-identifier: int (has symbols)

 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 :ref:`here <device_identifier>`.
 |device_identifier_constant|
 


Callback Configuration Functions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^



.. sh:function:: tinkerforge call line-bricklet <uid> set-reflectivity-callback-period <period> 

 :param <period>: int

 :noreturn: no output

 Sets the period in ms with which the :sh:func:`reflectivity <line-bricklet reflectivity>` callback is triggered
 periodically. A value of 0 turns the callback off.
 
 :sh:func:`reflectivity <line-bricklet reflectivity>` is only triggered if the reflectivity has changed since the
 last triggering.
 
 The default value is 0.
 
.. sh:function:: tinkerforge call line-bricklet <uid> get-reflectivity-callback-period  


 :returns period: int

 Returns the period as set by :sh:func:`set-reflectivity-callback-period <line-bricklet set-reflectivity-callback-period>`.
 
.. sh:function:: tinkerforge call line-bricklet <uid> set-reflectivity-callback-threshold <option> <min> <max> 

 :param <option>: char (has symbols)
 :param <min>: int
 :param <max>: int

 :noreturn: no output

 Sets the thresholds for the :sh:func:`reflectivity-reached <line-bricklet reflectivity-reached>` callback. 
 
 The following options are possible:
 
 .. csv-table::
  :header: "Option", "Description"
  :widths: 10, 100
 
  "'x'",    "Callback is turned off"
  "'o'",    "Callback is triggered when the reflectivity is *outside* the min and max values"
  "'i'",    "Callback is triggered when the reflectivity is *inside* the min and max values"
  "'<'",    "Callback is triggered when the reflectivity is smaller than the min value (max is ignored)"
  "'>'",    "Callback is triggered when the reflectivity is greater than the min value (max is ignored)"
 
 The default value is ('x', 0, 0).
 
 The following symbols are available for this function:
 
 * ``off`` = x, for <option>
 * ``outside`` = o, for <option>
 * ``inside`` = i, for <option>
 * ``smaller`` = <, for <option>
 * ``greater`` = >, for <option>
 
.. sh:function:: tinkerforge call line-bricklet <uid> get-reflectivity-callback-threshold  


 :returns option: char (has symbols)
 :returns min: int
 :returns max: int

 Returns the threshold as set by :sh:func:`set-reflectivity-callback-threshold <line-bricklet set-reflectivity-callback-threshold>`.
 
 The following symbols are available for this function:
 
 * ``off`` = x, for option
 * ``outside`` = o, for option
 * ``inside`` = i, for option
 * ``smaller`` = <, for option
 * ``greater`` = >, for option
 
.. sh:function:: tinkerforge call line-bricklet <uid> set-debounce-period <debounce> 

 :param <debounce>: int

 :noreturn: no output

 Sets the period in ms with which the threshold callback
 
 * :sh:func:`reflectivity-reached <line-bricklet reflectivity-reached>`
 
 is triggered, if the threshold
 
 * :sh:func:`set-reflectivity-callback-threshold <line-bricklet set-reflectivity-callback-threshold>`
 
 keeps being reached.
 
 The default value is 100.
 
.. sh:function:: tinkerforge call line-bricklet <uid> get-debounce-period  


 :returns debounce: int

 Returns the debounce period as set by :sh:func:`set-debounce-period <line-bricklet set-debounce-period>`.
 


.. _line_bricklet_shell_callbacks:

Callbacks
^^^^^^^^^

Callbacks can be used to receive time critical or recurring data from the
device:

.. code-block:: bash

    tinkerforge dispatch line-bricklet <uid> example

The available callbacks 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.

.. sh:function::  tinkerforge dispatch line-bricklet <uid> reflectivity

 :returns reflectivity: int


 This callback is triggered periodically with the period that is set by
 :sh:func:`set-reflectivity-callback-period <line-bricklet set-reflectivity-callback-period>`. The parameter is the reflectivity
 of the sensor.
 
 :sh:func:`reflectivity <line-bricklet reflectivity>` is only triggered if the reflectivity has changed since the
 last triggering.
 
.. sh:function::  tinkerforge dispatch line-bricklet <uid> reflectivity-reached

 :returns reflectivity: int


 This callback is triggered when the threshold as set by
 :sh:func:`set-reflectivity-callback-threshold <line-bricklet set-reflectivity-callback-threshold>` is reached.
 The parameter is the reflectivity of the sensor.
 
 If the threshold keeps being reached, the callback is triggered periodically
 with the period as set by :sh:func:`set-debounce-period <line-bricklet set-debounce-period>`.
 


