Shell - Distance IR Bricklet

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

# Get current distance
tinkerforge call distance-ir-bricklet $uid get-distance

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 IR Bricklet

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

# Set period for distance callback to 0.2s (200ms)
# Note: The distance callback is only called every 0.2 seconds
#       if the distance has changed since the last call!
tinkerforge call distance-ir-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 IR Bricklet

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

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

# Configure threshold for distance "smaller than 30 cm"
tinkerforge call distance-ir-bricklet $uid set-distance-callback-threshold threshold-option-smaller 300 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-ir-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

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

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

Returns the distance measured by the sensor. The value is in mm and possible distance ranges are 40 to 300, 100 to 800 and 200 to 1500, depending on the selected IR sensor.

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

Advanced Functions

tinkerforge call distance-ir-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-distance 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 distance-ir-bricklet <uid> set-sampling-point <position> <distance>
Parameters:
  • <position> -- int
  • <distance> -- int
Output:

no output

Sets a sampling point value to a specific position of the lookup table. The lookup table comprises 128 equidistant analog values with corresponding distances.

If you measure a distance of 50cm at the analog value 2048, you should call this function with (64, 5000). The utilized analog-to-digital converter has a resolution of 12 bit. With 128 sampling points on the whole range, this means that every sampling point has a size of 32 analog values. Thus the analog value 2048 has the corresponding sampling point 64 = 2048/32.

Sampling points are saved on the EEPROM of the Distance IR Bricklet and loaded again on startup.

Note

An easy way to calibrate the sampling points of the Distance IR Bricklet is implemented in the Brick Viewer. If you want to calibrate your Bricklet it is highly recommended to use this implementation.

tinkerforge call distance-ir-bricklet <uid> get-sampling-point <position>
Parameters:
  • <position> -- int
Output:
  • distance -- int

Returns the distance to a sampling point position as set by set-sampling-point.

tinkerforge call distance-ir-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-ir-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.

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

The default value is 0.

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

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

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

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

tinkerforge call distance-ir-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 is outside the min and max values
'i' Callback is triggered when the distance is inside the min and max values
'<' Callback is triggered when the distance is smaller than the min value (max is ignored)
'>' Callback is triggered when the distance 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-ir-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-ir-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 distance-ir-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 distance-ir-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-ir-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-ir-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-ir-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 of the sensor.

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

tinkerforge dispatch distance-ir-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 sensor.

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

tinkerforge dispatch distance-ir-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 of the sensor.

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

tinkerforge dispatch distance-ir-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 sensor.

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