Shell - Linear Poti Bricklet 2.0

This is the description of the Shell API bindings for the Linear Poti Bricklet 2.0. General information and technical specifications for the Linear Poti Bricklet 2.0 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 Linear Poti Bricklet 2.0

# Get current position
tinkerforge call linear-poti-v2-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 Linear Poti Bricklet 2.0

# Handle incoming position callbacks
tinkerforge dispatch linear-poti-v2-bricklet $uid position &

# Set period for position callback to 0.25s (250ms) without a threshold
tinkerforge call linear-poti-v2-bricklet $uid set-position-callback-configuration 250 false threshold-option-off 0 0

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 linear-poti-v2-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> – Type: String
  • <function> – Type: String

The call command is used to call a function of the Linear Poti Bricklet 2.0. 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 Linear Poti Bricklet 2.0 and exits
tinkerforge dispatch linear-poti-v2-bricklet [<option>..] <uid> <callback>
Parameters:
  • <uid> – Type: String
  • <callback> – Type: String

The dispatch command is used to dispatch a callback of the Linear Poti Bricklet 2.0. 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 Linear Poti Bricklet 2.0 and exits
tinkerforge call linear-poti-v2-bricklet <uid> <function> [<option>..] [<argument>..]
Parameters:
  • <uid> – Type: String
  • <function> – Type: 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 sent and errors are silently ignored, because they cannot be detected.

tinkerforge dispatch linear-poti-v2-bricklet <uid> <callback> [<option>..]
Parameters:
  • <uid> – Type: String
  • <callback> – Type: 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 linear-poti-v2-bricklet <uid> get-position
Output:
  • position – Type: Int, Unit: 1 %, Range: [0 to 100]

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.

Advanced Functions

tinkerforge call linear-poti-v2-bricklet <uid> get-spitfp-error-count
Output:
  • error-count-ack-checksum – Type: Int, Range: [0 to 232 - 1]
  • error-count-message-checksum – Type: Int, Range: [0 to 232 - 1]
  • error-count-frame – Type: Int, Range: [0 to 232 - 1]
  • error-count-overflow – Type: Int, Range: [0 to 232 - 1]

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 linear-poti-v2-bricklet <uid> set-status-led-config <config>
Parameters:
  • <config> – Type: Int, Range: See symbols, Default: 3
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:

For <config>:

  • status-led-config-off = 0
  • status-led-config-on = 1
  • status-led-config-show-heartbeat = 2
  • status-led-config-show-status = 3
tinkerforge call linear-poti-v2-bricklet <uid> get-status-led-config
Output:
  • config – Type: Int, Range: See symbols, Default: 3

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

The following symbols are available for this function:

For config:

  • status-led-config-off = 0
  • status-led-config-on = 1
  • status-led-config-show-heartbeat = 2
  • status-led-config-show-status = 3
tinkerforge call linear-poti-v2-bricklet <uid> get-chip-temperature
Output:
  • temperature – Type: Int, Unit: 1 °C, Range: [-215 to 215 - 1]

Returns the temperature 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 linear-poti-v2-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 linear-poti-v2-bricklet <uid> get-identity
Output:
  • uid – Type: String, Length: up to 8
  • connected-uid – Type: String, Length: up to 8
  • position – Type: Char, Range: [a to h, z]
  • hardware-version – Type: Int Array, Length: 3
    • 0: major – Type: Int, Range: [0 to 255]
    • 1: minor – Type: Int, Range: [0 to 255]
    • 2: revision – Type: Int, Range: [0 to 255]
  • firmware-version – Type: Int Array, Length: 3
    • 0: major – Type: Int, Range: [0 to 255]
    • 1: minor – Type: Int, Range: [0 to 255]
    • 2: revision – Type: Int, Range: [0 to 255]
  • device-identifier – Type: Int, Range: [0 to 216 - 1]

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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here

Callback Configuration Functions

tinkerforge call linear-poti-v2-bricklet <uid> set-position-callback-configuration <period> <value-has-to-change> <option> <min> <max>
Parameters:
  • <period> – Type: Int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • <value-has-to-change> – Type: Bool, Default: false
  • <option> – Type: Char, Range: See symbols, Default: x
  • <min> – Type: Int, Unit: 1 %, Range: [0 to 255], Default: 0
  • <max> – Type: Int, Unit: 1 %, Range: [0 to 255], Default: 0
Output:
  • no output

The period 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 following symbols are available for this function:

For <option>:

  • threshold-option-off = x
  • threshold-option-outside = o
  • threshold-option-inside = i
  • threshold-option-smaller = <
  • threshold-option-greater = >
tinkerforge call linear-poti-v2-bricklet <uid> get-position-callback-configuration
Output:
  • period – Type: Int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value-has-to-change – Type: Bool, Default: false
  • option – Type: Char, Range: See symbols, Default: x
  • min – Type: Int, Unit: 1 %, Range: [0 to 255], Default: 0
  • max – Type: Int, Unit: 1 %, Range: [0 to 255], Default: 0

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

The following symbols are available for this function:

For option:

  • threshold-option-off = x
  • threshold-option-outside = o
  • threshold-option-inside = i
  • threshold-option-smaller = <
  • threshold-option-greater = >

Callbacks

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

tinkerforge dispatch linear-poti-v2-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 linear-poti-v2-bricklet <uid> position
Output:
  • position – Type: Int, Unit: 1 %, Range: [0 to 100]

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

The parameter is the same as get-position.

Internal Functions

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

tinkerforge call linear-poti-v2-bricklet <uid> set-bootloader-mode <mode>
Parameters:
  • <mode> – Type: Int, Range: See symbols
Output:
  • status – Type: Int, Range: See 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:

For <mode>:

  • bootloader-mode-bootloader = 0
  • bootloader-mode-firmware = 1
  • bootloader-mode-bootloader-wait-for-reboot = 2
  • bootloader-mode-firmware-wait-for-reboot = 3
  • bootloader-mode-firmware-wait-for-erase-and-reboot = 4

For status:

  • bootloader-status-ok = 0
  • bootloader-status-invalid-mode = 1
  • bootloader-status-no-change = 2
  • bootloader-status-entry-function-not-present = 3
  • bootloader-status-device-identifier-incorrect = 4
  • bootloader-status-crc-mismatch = 5
tinkerforge call linear-poti-v2-bricklet <uid> get-bootloader-mode
Output:
  • mode – Type: Int, Range: See symbols

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

The following symbols are available for this function:

For mode:

  • bootloader-mode-bootloader = 0
  • bootloader-mode-firmware = 1
  • bootloader-mode-bootloader-wait-for-reboot = 2
  • bootloader-mode-firmware-wait-for-reboot = 3
  • bootloader-mode-firmware-wait-for-erase-and-reboot = 4
tinkerforge call linear-poti-v2-bricklet <uid> set-write-firmware-pointer <pointer>
Parameters:
  • <pointer> – Type: Int, Unit: 1 B, Range: [0 to 232 - 1]
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 linear-poti-v2-bricklet <uid> write-firmware <data>
Parameters:
  • <data> – Type: Int Array, Length: 64, Range: [0 to 255]
Output:
  • status – Type: Int, Range: [0 to 255]

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 linear-poti-v2-bricklet <uid> write-uid <uid>
Parameters:
  • <uid> – Type: Int, Range: [0 to 232 - 1]
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 linear-poti-v2-bricklet <uid> read-uid
Output:
  • uid – Type: Int, Range: [0 to 232 - 1]

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