Shell - Rotary Poti Bricklet

This is the description of the Shell API bindings for the Rotary Poti Bricklet. General information and technical specifications for the Rotary Poti Bricklet are summarized in its hardware description.

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

Examples

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

Simple

Download (example-simple.sh)

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#!/bin/sh
# Connects to localhost:4223 by default, use --host and --port to change this

uid=XYZ # Change XYZ to the UID of your Rotary Poti Bricklet

# Get current position
tinkerforge call rotary-poti-bricklet $uid get-position

Callback

Download (example-callback.sh)

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#!/bin/sh
# Connects to localhost:4223 by default, use --host and --port to change this

uid=XYZ # Change XYZ to the UID of your Rotary Poti Bricklet

# Handle incoming position callbacks
tinkerforge dispatch rotary-poti-bricklet $uid position &

# Set period for position callback to 0.05s (50ms)
# Note: The position callback is only called every 0.05 seconds
#       if the position has changed since the last call!
tinkerforge call rotary-poti-bricklet $uid set-position-callback-period 50

echo "Press key to exit"; read dummy

kill -- -$$ # Stop callback dispatch in background

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 here. The specific command structure is shown below.

tinkerforge call rotary-poti-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The call command is used to call a function of the Rotary Poti 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 Rotary Poti Bricklet and exits
tinkerforge dispatch rotary-poti-bricklet [<option>..] <uid> <callback>
Parameters:
  • <uid> -- string
  • <callback> -- string

The dispatch command is used to dispatch a callback of the Rotary Poti 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 Rotary Poti Bricklet and exits
tinkerforge call rotary-poti-bricklet <uid> <function> [<option>..] [<argument>..]
Parameters:
  • <uid> -- string
  • <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 output formatting 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.

tinkerforge dispatch rotary-poti-bricklet <uid> <callback> [<option>..]
Parameters:
  • <uid> -- string
  • <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 output formatting for details)

Basic Functions

tinkerforge call rotary-poti-bricklet <uid> get-position
Output:
  • position -- int

Returns the position of the rotary potentiometer. The value is in degree and between -150° (turned left) and 150° (turned right).

If you want to get the position periodically, it is recommended to use the position callback and set the period with set-position-callback-period.

Advanced Functions

tinkerforge call rotary-poti-bricklet <uid> get-analog-value
Output:
  • value -- int

Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.

Note

The value returned by get-position is averaged over several samples to yield less noise, while get-analog-value gives back raw unfiltered analog values. The only reason to use get-analog-value is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the analog-value callback and set the period with set-analog-value-callback-period.

tinkerforge call rotary-poti-bricklet <uid> get-identity
Output:
  • uid -- string
  • connected-uid -- string
  • position -- char
  • hardware-version -- int,int,int
  • firmware-version -- int,int,int
  • 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 here

Callback Configuration Functions

tinkerforge call rotary-poti-bricklet <uid> set-position-callback-period <period>
Parameters:
  • <period> -- int
Output:

no output

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

The position callback is only triggered if the position has changed since the last triggering.

The default value is 0.

tinkerforge call rotary-poti-bricklet <uid> get-position-callback-period
Output:
  • period -- int

Returns the period as set by set-position-callback-period.

tinkerforge call rotary-poti-bricklet <uid> set-analog-value-callback-period <period>
Parameters:
  • <period> -- int
Output:

no output

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

The analog-value callback is only triggered if the analog value has changed since the last triggering.

The default value is 0.

tinkerforge call rotary-poti-bricklet <uid> get-analog-value-callback-period
Output:
  • period -- int

Returns the period as set by set-analog-value-callback-period.

tinkerforge call rotary-poti-bricklet <uid> set-position-callback-threshold <option> <min> <max>
Parameters:
  • <option> -- char (has symbols)
  • <min> -- int
  • <max> -- int
Output:

no output

Sets the thresholds for the position-reached callback.

The following options are possible:

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

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

The following symbols are available for this function:

  • threshold-option-off = x, for <option>
  • threshold-option-outside = o, for <option>
  • threshold-option-inside = i, for <option>
  • threshold-option-smaller = <, for <option>
  • threshold-option-greater = >, for <option>
tinkerforge call rotary-poti-bricklet <uid> get-position-callback-threshold
Output:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by set-position-callback-threshold.

The following symbols are available for this function:

  • threshold-option-off = x, for option
  • threshold-option-outside = o, for option
  • threshold-option-inside = i, for option
  • threshold-option-smaller = <, for option
  • threshold-option-greater = >, for option
tinkerforge call rotary-poti-bricklet <uid> set-analog-value-callback-threshold <option> <min> <max>
Parameters:
  • <option> -- char (has symbols)
  • <min> -- int
  • <max> -- int
Output:

no output

Sets the thresholds for the analog-value-reached callback.

The following options are possible:

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

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

The following symbols are available for this function:

  • threshold-option-off = x, for <option>
  • threshold-option-outside = o, for <option>
  • threshold-option-inside = i, for <option>
  • threshold-option-smaller = <, for <option>
  • threshold-option-greater = >, for <option>
tinkerforge call rotary-poti-bricklet <uid> get-analog-value-callback-threshold
Output:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by set-analog-value-callback-threshold.

The following symbols are available for this function:

  • threshold-option-off = x, for option
  • threshold-option-outside = o, for option
  • threshold-option-inside = i, for option
  • threshold-option-smaller = <, for option
  • threshold-option-greater = >, for option
tinkerforge call rotary-poti-bricklet <uid> set-debounce-period <debounce>
Parameters:
  • <debounce> -- int
Output:

no output

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

tinkerforge call rotary-poti-bricklet <uid> get-debounce-period
Output:
  • debounce -- int

Returns the debounce period as set by set-debounce-period.

Callbacks

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

tinkerforge dispatch rotary-poti-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.

tinkerforge dispatch rotary-poti-bricklet <uid> position
Output:
  • position -- int

This callback is triggered periodically with the period that is set by set-position-callback-period. The parameter is the position of the rotary potentiometer.

The position callback is only triggered if the position has changed since the last triggering.

tinkerforge dispatch rotary-poti-bricklet <uid> analog-value
Output:
  • value -- int

This callback is triggered periodically with the period that is set by set-analog-value-callback-period. The parameter is the analog value of the rotary potentiometer.

The analog-value callback is only triggered if the position has changed since the last triggering.

tinkerforge dispatch rotary-poti-bricklet <uid> position-reached
Output:
  • position -- int

This callback is triggered when the threshold as set by set-position-callback-threshold is reached. The parameter is the position of the rotary potentiometer.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by set-debounce-period.

tinkerforge dispatch rotary-poti-bricklet <uid> analog-value-reached
Output:
  • value -- int

This callback is triggered when the threshold as set by set-analog-value-callback-threshold is reached. The parameter is the analog value of the rotary potentiometer.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by set-debounce-period.