Shell - Distance US Bricklet

This is the description of the Shell API bindings for the Distance US Bricklet. General information and technical specifications for the Distance US 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 Distance US Bricklet

# Get current distance value
tinkerforge call distance-us-bricklet $uid get-distance-value

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 Distance US Bricklet

# Handle incoming distance value callbacks
tinkerforge dispatch distance-us-bricklet $uid distance &

# Set period for distance value callback to 0.2s (200ms)
# Note: The distance value callback is only called every 0.2 seconds
#       if the distance value has changed since the last call!
tinkerforge call distance-us-bricklet $uid set-distance-callback-period 200

echo "Press key to exit"; read dummy

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

Threshold

Download (example-threshold.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 Distance US Bricklet

# Get threshold callbacks with a debounce time of 10 seconds (10000ms)
tinkerforge call distance-us-bricklet $uid set-debounce-period 10000

# Handle incoming distance value reached callbacks
tinkerforge dispatch distance-us-bricklet $uid distance-reached &

# Configure threshold for distance value "smaller than 200"
tinkerforge call distance-us-bricklet $uid set-distance-callback-threshold threshold-option-smaller 200 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 distance-us-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The call command is used to call a function of the Distance US 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 Distance US Bricklet and exits
tinkerforge dispatch distance-us-bricklet [<option>..] <uid> <callback>
Parameters:
  • <uid> -- string
  • <callback> -- string

The dispatch command is used to dispatch a callback of the Distance US 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 Distance US Bricklet and exits
tinkerforge call distance-us-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 distance-us-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 distance-us-bricklet <uid> get-distance-value
Output:
  • distance -- int

Returns the current distance value measured by the sensor. The value has a range of 0 to 4095. A small value corresponds to a small distance, a big value corresponds to a big distance. The relation between the measured distance value and the actual distance is affected by the 5V supply voltage (deviations in the supply voltage result in deviations in the distance values) and is non-linear (resolution is bigger at close range).

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

Advanced Functions

tinkerforge call distance-us-bricklet <uid> set-moving-average <average>
Parameters:
  • <average> -- int
Output:

no output

Sets the length of a moving averaging for the distance value.

Setting the length to 0 will turn the averaging completely off. With less averaging, there is more noise on the data.

The range for the averaging is 0-100.

The default value is 20.

tinkerforge call distance-us-bricklet <uid> get-moving-average
Output:
  • average -- int

Returns the length moving average as set by set-moving-average.

tinkerforge call distance-us-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 distance-us-bricklet <uid> set-distance-callback-period <period>
Parameters:
  • <period> -- int
Output:

no output

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

Der distance callback is only triggered if the distance value has changed since the last triggering.

The default value is 0.

tinkerforge call distance-us-bricklet <uid> get-distance-callback-period
Output:
  • period -- int

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

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

no output

Sets the thresholds for the distance-reached callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the distance value is outside the min and max values
'i' Callback is triggered when the distance value is inside the min and max values
'<' Callback is triggered when the distance value is smaller than the min value (max is ignored)
'>' Callback is triggered when the distance 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 distance-us-bricklet <uid> get-distance-callback-threshold
Output:
  • option -- char (has symbols)
  • min -- int
  • max -- int

Returns the threshold as set by set-distance-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 distance-us-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 distance-us-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 distance-us-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 distance-us-bricklet <uid> distance
Output:
  • distance -- int

This callback is triggered periodically with the period that is set by set-distance-callback-period. The parameter is the distance value of the sensor.

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

tinkerforge dispatch distance-us-bricklet <uid> distance-reached
Output:
  • distance -- int

This callback is triggered when the threshold as set by set-distance-callback-threshold is reached. The parameter is the distance value of the sensor.

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