Shell - Barometer Bricklet

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

# Get current air pressure
tinkerforge call barometer-bricklet $uid get-air-pressure

# Get current altitude
tinkerforge call barometer-bricklet $uid get-altitude

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 Barometer Bricklet

# Handle incoming air pressure callbacks
tinkerforge dispatch barometer-bricklet $uid air-pressure &

# Set period for air pressure callback to 1s (1000ms)
# Note: The air pressure callback is only called every second
#       if the air pressure has changed since the last call!
tinkerforge call barometer-bricklet $uid set-air-pressure-callback-period 1000

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 Barometer Bricklet

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

# Handle incoming air pressure reached callbacks
tinkerforge dispatch barometer-bricklet $uid air-pressure-reached\
 --execute "echo Air Pressure: {air_pressure}/1000 mbar. Enjoy the potentially good weather!" &

# Configure threshold for air pressure "greater than 1025 mbar"
tinkerforge call barometer-bricklet $uid set-air-pressure-callback-threshold threshold-option-greater 1025000 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 barometer-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

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

The dispatch command is used to dispatch a callback of the Barometer 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 Barometer Bricklet and exits
tinkerforge call barometer-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 barometer-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 barometer-bricklet <uid> get-air-pressure
Output:
  • air-pressure -- int

Returns the air pressure of the air pressure sensor. The value has a range of 10000 to 1200000 and is given in mbar/1000, i.e. a value of 1001092 means that an air pressure of 1001.092 mbar is measured.

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

tinkerforge call barometer-bricklet <uid> get-altitude
Output:
  • altitude -- int

Returns the relative altitude of the air pressure sensor. The value is given in cm and is calculated based on the difference between the current air pressure and the reference air pressure that can be set with set-reference-air-pressure.

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

tinkerforge call barometer-bricklet <uid> set-reference-air-pressure <air-pressure>
Parameters:
  • <air-pressure> -- int
Output:

no output

Sets the reference air pressure in mbar/1000 for the altitude calculation. Valid values are between 10000 and 1200000. Setting the reference to the current air pressure results in a calculated altitude of 0cm. Passing 0 is a shortcut for passing the current air pressure as reference.

Well known reference values are the Q codes QNH and QFE used in aviation.

The default value is 1013.25mbar.

tinkerforge call barometer-bricklet <uid> get-reference-air-pressure
Output:
  • air-pressure -- int

Returns the reference air pressure as set by set-reference-air-pressure.

Advanced Functions

tinkerforge call barometer-bricklet <uid> get-chip-temperature
Output:
  • temperature -- int

Returns the temperature of the air pressure sensor. The value has a range of -4000 to 8500 and is given in °C/100, i.e. a value of 2007 means that a temperature of 20.07 °C is measured.

This temperature is used internally for temperature compensation of the air pressure measurement. It is not as accurate as the temperature measured by the Temperature Bricklet or the Temperature IR Bricklet.

tinkerforge call barometer-bricklet <uid> set-averaging <moving-average-pressure> <average-pressure> <average-temperature>
Parameters:
  • <moving-average-pressure> -- int
  • <average-pressure> -- int
  • <average-temperature> -- int
Output:

no output

Sets the different averaging parameters. It is possible to set the length of a normal averaging for the temperature and pressure, as well as an additional length of a moving average for the pressure. The moving average is calculated from the normal averages. There is no moving average for the temperature.

The maximum length for the pressure average is 10, for the temperature average is 255 and for the moving average is 25.

Setting the all three parameters to 0 will turn the averaging completely off. If the averaging is off, there is lots of noise on the data, but the data is without delay. Thus we recommend to turn the averaging off if the Barometer Bricklet data is to be used for sensor fusion with other sensors.

The default values are 10 for the normal averages and 25 for the moving average.

New in version 2.0.1 (Plugin).

tinkerforge call barometer-bricklet <uid> get-averaging
Output:
  • moving-average-pressure -- int
  • average-pressure -- int
  • average-temperature -- int

Returns the averaging configuration as set by set-averaging.

New in version 2.0.1 (Plugin).

tinkerforge call barometer-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 barometer-bricklet <uid> set-air-pressure-callback-period <period>
Parameters:
  • <period> -- int
Output:

no output

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

The air-pressure callback is only triggered if the air pressure has changed since the last triggering.

The default value is 0.

tinkerforge call barometer-bricklet <uid> get-air-pressure-callback-period
Output:
  • period -- int

Returns the period as set by set-air-pressure-callback-period.

tinkerforge call barometer-bricklet <uid> set-altitude-callback-period <period>
Parameters:
  • <period> -- int
Output:

no output

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

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

The default value is 0.

tinkerforge call barometer-bricklet <uid> get-altitude-callback-period
Output:
  • period -- int

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

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

no output

Sets the thresholds for the air-pressure-reached callback.

The following options are possible:

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

Returns the threshold as set by set-air-pressure-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 barometer-bricklet <uid> set-altitude-callback-threshold <option> <min> <max>
Parameters:
  • <option> -- char (has symbols)
  • <min> -- int
  • <max> -- int
Output:

no output

Sets the thresholds for the altitude-reached callback.

The following options are possible:

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

Returns the threshold as set by set-altitude-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 barometer-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 barometer-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 barometer-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 barometer-bricklet <uid> air-pressure
Output:
  • air-pressure -- int

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

The air-pressure callback is only triggered if the air pressure has changed since the last triggering.

tinkerforge dispatch barometer-bricklet <uid> altitude
Output:
  • altitude -- int

This callback is triggered periodically with the period that is set by set-altitude-callback-period. The parameter is the altitude of the air pressure sensor.

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

tinkerforge dispatch barometer-bricklet <uid> air-pressure-reached
Output:
  • air-pressure -- int

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

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

tinkerforge dispatch barometer-bricklet <uid> altitude-reached
Output:
  • altitude -- int

This callback is triggered when the threshold as set by set-altitude-callback-threshold is reached. The parameter is the altitude of the air pressure sensor.

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