Shell - Motorized Linear Poti Bricklet

This is the description of the Shell API bindings for the Motorized Linear Poti Bricklet. General information and technical specifications for the Motorized Linear 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 Motorized Linear Poti Bricklet

# Get current position
tinkerforge call motorized-linear-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 Motorized Linear Poti Bricklet

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

# Set period for position callback to 0.05s (50ms) without a threshold
tinkerforge call motorized-linear-poti-bricklet $uid set-position-callback-configuration 50 false threshold-option-off 0 0

echo "Press key to exit"; read dummy

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

Motor

Download (example-motor.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 Motorized Linear Poti Bricklet

# Handle incoming position reached callbacks
tinkerforge dispatch motorized-linear-poti-bricklet $uid position-reached &

# Move slider smooth to the middle
tinkerforge call motorized-linear-poti-bricklet $uid set-motor-position 50 drive-mode-smooth false

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 motorized-linear-poti-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

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

The dispatch command is used to dispatch a callback of the Motorized Linear 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 Motorized Linear Poti Bricklet and exits
tinkerforge call motorized-linear-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 motorized-linear-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 motorized-linear-poti-bricklet <uid> get-position
Output:
  • position -- int

Returns the position of the linear potentiometer. The value is between 0 (slider down) and 100 (slider up).

If you want to get the value periodically, it is recommended to use the position callback. You can set the callback configuration with set-position-callback-configuration.

tinkerforge call motorized-linear-poti-bricklet <uid> set-motor-position <position> <drive-mode> <hold-position>
Parameters:
  • <position> -- int
  • <drive-mode> -- int (has symbols)
  • <hold-position> -- bool
Output:

no output

Sets the position of the potentiometer. The motorized potentiometer will immediately start to approach the position. Depending on the chosen drive mode, the position will either be reached as fast as possible or in a slow but smooth motion.

The position has to be between 0 (slider down) and 100 (slider up).

If you set the hold position parameter to true, the position will automatically be retained. If a user changes the position of the potentiometer, it will automatically drive back to the original set point.

If the hold position parameter is set to false, the potentiometer can be changed again by the user as soon as the set point was reached once.

The following symbols are available for this function:

  • drive-mode-fast = 0, for <drive-mode>
  • drive-mode-smooth = 1, for <drive-mode>
tinkerforge call motorized-linear-poti-bricklet <uid> get-motor-position
Output:
  • position -- int
  • drive-mode -- int (has symbols)
  • hold-position -- bool
  • position-reached -- bool

Returns the last motor position as set by set-motor-position. This is not the current position (use get-position to get the current position). This is the last used set point and configuration.

The position reached parameter is true if the position has been reached at one point. The position may have been changed again in the meantime by the user.

The following symbols are available for this function:

  • drive-mode-fast = 0, for drive-mode
  • drive-mode-smooth = 1, for drive-mode

Advanced Functions

tinkerforge call motorized-linear-poti-bricklet <uid> calibrate
Output:no output

Starts a calibration procedure. The potentiometer will be driven to the extreme points to calibrate the potentiometer.

The calibration is saved in flash, it does not have to be called on every start up.

The Motorized Linear Poti Bricklet is already factory-calibrated during testing at Tinkerforge.

tinkerforge call motorized-linear-poti-bricklet <uid> get-spitfp-error-count
Output:
  • error-count-ack-checksum -- int
  • error-count-message-checksum -- int
  • error-count-frame -- int
  • error-count-overflow -- int

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

tinkerforge call motorized-linear-poti-bricklet <uid> set-bootloader-mode <mode>
Parameters:
  • <mode> -- int (has symbols)
Output:
  • status -- int (has symbols)

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following symbols are available for this function:

  • bootloader-mode-bootloader = 0, for <mode>
  • bootloader-mode-firmware = 1, for <mode>
  • bootloader-mode-bootloader-wait-for-reboot = 2, for <mode>
  • bootloader-mode-firmware-wait-for-reboot = 3, for <mode>
  • bootloader-mode-firmware-wait-for-erase-and-reboot = 4, for <mode>
  • bootloader-status-ok = 0, for status
  • bootloader-status-invalid-mode = 1, for status
  • bootloader-status-no-change = 2, for status
  • bootloader-status-entry-function-not-present = 3, for status
  • bootloader-status-device-identifier-incorrect = 4, for status
  • bootloader-status-crc-mismatch = 5, for status
tinkerforge call motorized-linear-poti-bricklet <uid> get-bootloader-mode
Output:
  • mode -- int (has symbols)

Returns the current bootloader mode, see set-bootloader-mode.

The following symbols are available for this function:

  • bootloader-mode-bootloader = 0, for mode
  • bootloader-mode-firmware = 1, for mode
  • bootloader-mode-bootloader-wait-for-reboot = 2, for mode
  • bootloader-mode-firmware-wait-for-reboot = 3, for mode
  • bootloader-mode-firmware-wait-for-erase-and-reboot = 4, for mode
tinkerforge call motorized-linear-poti-bricklet <uid> set-write-firmware-pointer <pointer>
Parameters:
  • <pointer> -- int
Output:

no output

Sets the firmware pointer for write-firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

tinkerforge call motorized-linear-poti-bricklet <uid> write-firmware <data>
Parameters:
  • <data> -- int,int,..61x..,int
Output:
  • status -- int

Writes 64 Bytes of firmware at the position as written by set-write-firmware-pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

tinkerforge call motorized-linear-poti-bricklet <uid> set-status-led-config <config>
Parameters:
  • <config> -- int (has symbols)
Output:

no output

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following symbols are available for this function:

  • status-led-config-off = 0, for <config>
  • status-led-config-on = 1, for <config>
  • status-led-config-show-heartbeat = 2, for <config>
  • status-led-config-show-status = 3, for <config>
tinkerforge call motorized-linear-poti-bricklet <uid> get-status-led-config
Output:
  • config -- int (has symbols)

Returns the configuration as set by set-status-led-config

The following symbols are available for this function:

  • status-led-config-off = 0, for config
  • status-led-config-on = 1, for config
  • status-led-config-show-heartbeat = 2, for config
  • status-led-config-show-status = 3, for config
tinkerforge call motorized-linear-poti-bricklet <uid> get-chip-temperature
Output:
  • temperature -- int

Returns the temperature in °C 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 bad accuracy. Practically it is only useful as an indicator for temperature changes.

tinkerforge call motorized-linear-poti-bricklet <uid> reset
Output:no output

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

tinkerforge call motorized-linear-poti-bricklet <uid> write-uid <uid>
Parameters:
  • <uid> -- int
Output:

no output

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

tinkerforge call motorized-linear-poti-bricklet <uid> read-uid
Output:
  • uid -- int

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

tinkerforge call motorized-linear-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 motorized-linear-poti-bricklet <uid> set-position-callback-configuration <period> <value-has-to-change> <option> <min> <max>
Parameters:
  • <period> -- int
  • <value-has-to-change> -- bool
  • <option> -- char (has symbols)
  • <min> -- int
  • <max> -- int
Output:

no output

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the position callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

The default value is (0, false, '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 motorized-linear-poti-bricklet <uid> get-position-callback-configuration
Output:
  • period -- int
  • value-has-to-change -- bool
  • option -- char (has symbols)
  • min -- int
  • max -- int

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

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 motorized-linear-poti-bricklet <uid> set-position-reached-callback-configuration <enabled>
Parameters:
  • <enabled> -- bool
Output:

no output

Enables/Disables position-reached callback.

By default the callback is enabled.

tinkerforge call motorized-linear-poti-bricklet <uid> get-position-reached-callback-configuration
Output:
  • enabled -- bool

Returns the position-reached callback configuration as set by set-position-reached-callback-configuration.

Callbacks

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

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

This callback is triggered periodically according to the configuration set by set-position-callback-configuration.

The parameter is the same as get-position.

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

This callback is triggered if a new position as set by set-motor-position is reached.

The parameter is the current position.