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

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

.. _dc_brick_shell:

Shell - DC Brick
================

This is the description of the :ref:`Shell API bindings <api_bindings_shell>` for the :ref:`DC Brick <dc_brick>`. General information and technical
specifications for the DC Brick are summarized in its :ref:`hardware description
<dc_brick_description>`.

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

.. _dc_brick_shell_examples:


Examples
--------

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

Configuration
^^^^^^^^^^^^^

`Download (example-configuration.sh) <https://github.com/Tinkerforge/dc-brick/raw/master/software/examples/shell/example-configuration.sh>`__

.. literalinclude:: DC_Brick_Shell_example-configuration.sh
 :language: bash
 :linenos:
 :tab-width: 4

Callback
^^^^^^^^

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

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

.. _dc_brick_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 Ndc-brick 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 DC Brick. 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 DC Brick and exits


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

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

 The ``dispatch`` command is used to dispatch a callback of the DC Brick. 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 DC Brick and exits


.. sh:function:: X Stinkerforge Scall Pdc-brick 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 Pdc-brick 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 dc-brick <uid> set-velocity <velocity> 

 :param <velocity>: int

 :noreturn: no output

 Sets the velocity of the motor. Whereas -32767 is full speed backward,
 0 is stop and 32767 is full speed forward. Depending on the
 acceleration (see :sh:func:`set-acceleration <dc-brick set-acceleration>`), the motor is not immediately
 brought to the velocity but smoothly accelerated.
 
 The velocity describes the duty cycle of the PWM with which the motor is
 controlled, e.g. a velocity of 3277 sets a PWM with a 10% duty cycle.
 You can not only control the duty cycle of the PWM but also the frequency,
 see :sh:func:`set-pwm-frequency <dc-brick set-pwm-frequency>`.
 
 The default velocity is 0.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-velocity  


 :returns velocity: int

 Returns the velocity as set by :sh:func:`set-velocity <dc-brick set-velocity>`.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-current-velocity  


 :returns velocity: int

 Returns the *current* velocity of the motor. This value is different
 from :sh:func:`get-velocity <dc-brick get-velocity>` whenever the motor is currently accelerating
 to a goal set by :sh:func:`set-velocity <dc-brick set-velocity>`.
 
.. sh:function:: tinkerforge call dc-brick <uid> set-acceleration <acceleration> 

 :param <acceleration>: int

 :noreturn: no output

 Sets the acceleration of the motor. It is given in *velocity/s*. An
 acceleration of 10000 means, that every second the velocity is increased
 by 10000 (or about 30% duty cycle).
 
 For example: If the current velocity is 0 and you want to accelerate to a
 velocity of 16000 (about 50% duty cycle) in 10 seconds, you should set
 an acceleration of 1600.
 
 If acceleration is set to 0, there is no speed ramping, i.e. a new velocity
 is immediately given to the motor.
 
 The default acceleration is 10000.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-acceleration  


 :returns acceleration: int

 Returns the acceleration as set by :sh:func:`set-acceleration <dc-brick set-acceleration>`.
 
.. sh:function:: tinkerforge call dc-brick <uid> full-brake  


 :noreturn: no output

 Executes an active full brake.
 
 .. warning::
  This function is for emergency purposes,
  where an immediate brake is necessary. Depending on the current velocity and
  the strength of the motor, a full brake can be quite violent.
 
 Call :sh:func:`set-velocity <dc-brick set-velocity>` with 0 if you just want to stop the motor.
 
.. sh:function:: tinkerforge call dc-brick <uid> enable  


 :noreturn: no output

 Enables the driver chip. The driver parameters can be configured (velocity,
 acceleration, etc) before it is enabled.
 
.. sh:function:: tinkerforge call dc-brick <uid> disable  


 :noreturn: no output

 Disables the driver chip. The configurations are kept (velocity,
 acceleration, etc) but the motor is not driven until it is enabled again.
 
.. sh:function:: tinkerforge call dc-brick <uid> is-enabled  


 :returns enabled: bool

 Returns *true* if the driver chip is enabled, *false* otherwise.
 


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

.. sh:function:: tinkerforge call dc-brick <uid> set-pwm-frequency <frequency> 

 :param <frequency>: int

 :noreturn: no output

 Sets the frequency (in Hz) of the PWM with which the motor is driven.
 The possible range of the frequency is 1-20000Hz. Often a high frequency
 is less noisy and the motor runs smoother. However, with a low frequency
 there are less switches and therefore fewer switching losses. Also with
 most motors lower frequencies enable higher torque.
 
 If you have no idea what all this means, just ignore this function and use
 the default frequency, it will very likely work fine.
 
 The default frequency is 15 kHz.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-pwm-frequency  


 :returns frequency: int

 Returns the PWM frequency (in Hz) as set by :sh:func:`set-pwm-frequency <dc-brick set-pwm-frequency>`.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-stack-input-voltage  


 :returns voltage: int

 Returns the stack input voltage in mV. The stack input voltage is the
 voltage that is supplied via the stack, i.e. it is given by a
 Step-Down or Step-Up Power Supply.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-external-input-voltage  


 :returns voltage: int

 Returns the external input voltage in mV. The external input voltage is
 given via the black power input connector on the DC Brick.
 
 If there is an external input voltage and a stack input voltage, the motor
 will be driven by the external input voltage. If there is only a stack
 voltage present, the motor will be driven by this voltage.
 
 .. warning::
  This means, if you have a high stack voltage and a low external voltage,
  the motor will be driven with the low external voltage. If you then remove
  the external connection, it will immediately be driven by the high
  stack voltage.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-current-consumption  


 :returns voltage: int

 Returns the current consumption of the motor in mA.
 
.. sh:function:: tinkerforge call dc-brick <uid> set-drive-mode <mode> 

 :param <mode>: int (has symbols)

 :noreturn: no output

 Sets the drive mode. Possible modes are:
 
 * 0 = Drive/Brake
 * 1 = Drive/Coast
 
 These modes are different kinds of motor controls.
 
 In Drive/Brake mode, the motor is always either driving or braking. There
 is no freewheeling. Advantages are: A more linear correlation between
 PWM and velocity, more exact accelerations and the possibility to drive
 with slower velocities.
 
 In Drive/Coast mode, the motor is always either driving or freewheeling.
 Advantages are: Less current consumption and less demands on the motor and
 driver chip.
 
 The default value is 0 = Drive/Brake.
 
 The following symbols are available for this function:
 
 * ``drive-brake`` = 0, for <mode>
 * ``drive-coast`` = 1, for <mode>
 
.. sh:function:: tinkerforge call dc-brick <uid> get-drive-mode  


 :returns mode: int (has symbols)

 Returns the drive mode, as set by :sh:func:`set-drive-mode <dc-brick set-drive-mode>`.
 
 The following symbols are available for this function:
 
 * ``drive-brake`` = 0, for mode
 * ``drive-coast`` = 1, for mode
 
.. sh:function:: tinkerforge call dc-brick <uid> enable-status-led  


 :noreturn: no output

 Enables the status LED.
 
 The status LED is the blue LED next to the USB connector. If enabled is is
 on and it flickers if data is transfered. If disabled it is always off.
 
 The default state is enabled.
 
 .. versionadded:: 2.3.1~(Firmware)
 
.. sh:function:: tinkerforge call dc-brick <uid> disable-status-led  


 :noreturn: no output

 Disables the status LED.
 
 The status LED is the blue LED next to the USB connector. If enabled is is
 on and it flickers if data is transfered. If disabled it is always off.
 
 The default state is enabled.
 
 .. versionadded:: 2.3.1~(Firmware)
 
.. sh:function:: tinkerforge call dc-brick <uid> is-status-led-enabled  


 :returns enabled: bool

 Returns *true* if the status LED is enabled, *false* otherwise.
 
 .. versionadded:: 2.3.1~(Firmware)
 
.. sh:function:: tinkerforge call dc-brick <uid> get-protocol1-bricklet-name <port> 

 :param <port>: char

 :returns protocol-version: int
 :returns firmware-version: int,int,int
 :returns name: string

 Returns the firmware and protocol version and the name of the Bricklet for a
 given port.
 
 This functions sole purpose is to allow automatic flashing of v1.x.y Bricklet
 plugins.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-chip-temperature  


 :returns temperature: int

 Returns the temperature in °C/10 as measured inside the microcontroller. The
 value returned is not the ambient temperature!
 
 The temperature is only proportional to the real temperature and it has an
 accuracy of +-15%. Practically it is only useful as an indicator for
 temperature changes.
 
.. sh:function:: tinkerforge call dc-brick <uid> reset  


 :noreturn: no output

 Calling this function will reset the Brick. Calling this function
 on a Brick inside of a stack will reset the whole stack.
 
 After a reset you have to create new device objects,
 calling functions on the existing ones will result in
 undefined behavior!
 
.. sh:function:: tinkerforge call dc-brick <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 Brick is connected to, 
 the position, the hardware and firmware version as well as the
 device identifier.
 
 The position can be '0'-'8' (stack position).
 
 The device identifier numbers can be found :ref:`here <device_identifier>`.
 |device_identifier_constant|
 


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



.. sh:function:: tinkerforge call dc-brick <uid> set-minimum-voltage <voltage> 

 :param <voltage>: int

 :noreturn: no output

 Sets the minimum voltage in mV, below which the :sh:func:`under-voltage <dc-brick under-voltage>` callback
 is triggered. The minimum possible value that works with the DC Brick is 6V.
 You can use this function to detect the discharge of a battery that is used
 to drive the motor. If you have a fixed power supply, you likely do not need
 this functionality.
 
 The default value is 6V.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-minimum-voltage  


 :returns voltage: int

 Returns the minimum voltage as set by :sh:func:`set-minimum-voltage <dc-brick set-minimum-voltage>`
 
.. sh:function:: tinkerforge call dc-brick <uid> set-current-velocity-period <period> 

 :param <period>: int

 :noreturn: no output

 Sets a period in ms with which the :sh:func:`current-velocity <dc-brick current-velocity>` callback is triggered.
 A period of 0 turns the callback off.
 
 The default value is 0.
 
.. sh:function:: tinkerforge call dc-brick <uid> get-current-velocity-period  


 :returns period: int

 Returns the period as set by :sh:func:`set-current-velocity-period <dc-brick set-current-velocity-period>`.
 


.. _dc_brick_shell_callbacks:

Callbacks
^^^^^^^^^

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

.. code-block:: bash

    tinkerforge dispatch dc-brick <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 dc-brick <uid> under-voltage

 :returns voltage: int


 This callback is triggered when the input voltage drops below the value set by
 :sh:func:`set-minimum-voltage <dc-brick set-minimum-voltage>`. The parameter is the current voltage given
 in mV.
 
.. sh:function::  tinkerforge dispatch dc-brick <uid> emergency-shutdown

 :noreturn: no output


 This callback is triggered if either the current consumption
 is too high (above 5A) or the temperature of the driver chip is too high
 (above 175°C). These two possibilities are essentially the same, since the
 temperature will reach this threshold immediately if the motor consumes too
 much current. In case of a voltage below 3.3V (external or stack) this
 callback is triggered as well.
 
 If this callback is triggered, the driver chip gets disabled at the same time.
 That means, :sh:func:`enable <dc-brick enable>` has to be called to drive the motor again.
 
 .. note::
  This callback only works in Drive/Brake mode (see :sh:func:`set-drive-mode <dc-brick set-drive-mode>`). In
  Drive/Coast mode it is unfortunately impossible to reliably read the
  overcurrent/overtemperature signal from the driver chip.
 
.. sh:function::  tinkerforge dispatch dc-brick <uid> velocity-reached

 :returns velocity: int


 This callback is triggered whenever a set velocity is reached. For example:
 If a velocity of 0 is present, acceleration is set to 5000 and velocity
 to 10000, :sh:func:`velocity-reached <dc-brick velocity-reached>` will be triggered after about 2 seconds, when
 the set velocity is actually reached.
 
 .. note::
  Since we can't get any feedback from the DC motor, this only works if the
  acceleration (see :sh:func:`set-acceleration <dc-brick set-acceleration>`) is set smaller or equal to the
  maximum acceleration of the motor. Otherwise the motor will lag behind the
  control value and the callback will be triggered too early.
 
.. sh:function::  tinkerforge dispatch dc-brick <uid> current-velocity

 :returns velocity: int


 This callback is triggered with the period that is set by
 :sh:func:`set-current-velocity-period <dc-brick set-current-velocity-period>`. The parameter is the *current* velocity
 used by the motor.
 
 :sh:func:`current-velocity <dc-brick current-velocity>` is only triggered after the set period if there is
 a change in the velocity.
 


