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# Ruby - Barometer Bricklet

This is the description of the Ruby 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 Ruby API bindings is part of their general description.

## Examples

The example code below is Public Domain (CC0 1.0).

### Simple

Download (example_simple.rb)

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    #!/usr/bin/env ruby
    # -*- ruby encoding: utf-8 -*-

    require 'tinkerforge/ip_connection'
    require 'tinkerforge/bricklet_barometer'

    include Tinkerforge

    HOST = 'localhost'
    PORT = 4223
    UID = 'bAc' # Change to your UID

    ipcon = IPConnection.new # Create IP connection
    b = BrickletBarometer.new UID, ipcon # Create device object

    ipcon.connect HOST, PORT # Connect to brickd
    # Don't use device before ipcon is connected

    # Get current air pressure (unit is mbar/1000)
    air_pressure = b.get_air_pressure / 1000.0
    puts "Air Pressure: #{air_pressure} mbar"

    # Get current altitude (unit is cm)
    altitude = b.get_altitude / 100.0
    puts "Altitude: #{altitude} m"

    puts 'Press key to exit'
    $stdin.gets
    ipcon.disconnect

### Threshold

Download (example_threshold.rb)

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    #!/usr/bin/env ruby
    # -*- ruby encoding: utf-8 -*-

    require 'tinkerforge/ip_connection'
    require 'tinkerforge/bricklet_barometer'

    include Tinkerforge

    HOST = 'localhost'
    PORT = 4223
    UID = 'bAc' # Change to your UID

    ipcon = IPConnection.new # Create IP connection
    b = BrickletBarometer.new UID, ipcon # Create device object

    ipcon.connect HOST, PORT # Connect to brickd
    # Don't use device before ipcon is connected

    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    b.set_debounce_period 10000

    # Register threshold reached callback for air pressure greater than 1025 mbar
    b.register_callback(BrickletBarometer::CALLBACK_AIR_PRESSURE_REACHED) do |air_pressure|
      puts "We have #{air_pressure/1000.0} mbar."
      puts "Enjoy the potentially good weather!"
    end

    # Configure threshold for "greater than 1025 mbar" (unit is mbar/1000)
    b.set_air_pressure_callback_threshold '>', 1025*1000, 0

    puts 'Press key to exit'
    $stdin.gets
    ipcon.disconnect

### Callback

Download (example_callback.rb)

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    #!/usr/bin/env ruby
    # -*- ruby encoding: utf-8 -*-

    require 'tinkerforge/ip_connection'
    require 'tinkerforge/bricklet_barometer'

    include Tinkerforge

    HOST = 'localhost'
    PORT = 4223
    UID = 'bAc' # Change to your UID

    ipcon = IPConnection.new # Create IP connection
    b = BrickletBarometer.new UID, ipcon # Create device object

    ipcon.connect HOST, PORT # Connect to brickd
    # Don't use device before ipcon is connected

    # Set Period for air pressure and altitude callbacks to 1s (1000ms)
    # Note: The air pressure and altitude callbacks are only called every second
    #       if the air pressure or altitude has changed since the last call!
    b.set_air_pressure_callback_period 1000
    b.set_altitude_callback_period 1000

    # Register air pressure callback (parameter has unit mbar/1000)
    b.register_callback(BrickletBarometer::CALLBACK_AIR_PRESSURE) do |air_pressure|
      puts "Air Pressure: #{air_pressure/1000.0} mbar"
    end

    # Register altitude callback (parameter has unit cm)
    b.register_callback(BrickletBarometer::CALLBACK_ALTITUDE) do |altitude|
      puts "Altitude: #{altitude/100.0} m"
    end

    puts 'Press key to exit'
    $stdin.gets
    ipcon.disconnect

## API

All methods listed below are thread-safe.

### Basic Functions

`BrickletBarometer``::``new`(uid, ipcon) → barometer

  Parameters:

  - uid -- str
  - ipcon -- IPConnection

  Creates an object with the unique device ID `uid`:

      barometer = BrickletBarometer.new 'YOUR_DEVICE_UID', ipcon

  This object can then be used after the IP Connection is connected (see examples above).

`BrickletBarometer``#``get_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 callback `::CALLBACK_AIR_PRESSURE` and set the period with `#set_air_pressure_callback_period`.

`BrickletBarometer``#``get_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 callback `::CALLBACK_ALTITUDE` and set the period with `#set_altitude_callback_period`.

`BrickletBarometer``#``set_reference_air_pressure`(air_pressure) → nil

  Parameters: | air_pressure -- int

  Sets the reference air pressure in mbar/1000 for the altitude calculation. 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.

`BrickletBarometer``#``get_reference_air_pressure` → int

  Returns the reference air pressure as set by `#set_reference_air_pressure`.

### Advanced Functions

`BrickletBarometer``#``get_chip_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.

`BrickletBarometer``#``set_averaging`(moving_average_pressure, average_pressure, average_temperature) → nil

  Parameters:

  - moving_average_pressure -- int
  - average_pressure -- int
  - average_temperature -- int

  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).

`BrickletBarometer``#``get_averaging` → [int, int, int]

  Returns the averaging configuration as set by `#set_averaging`.

  New in version 2.0.1 (Plugin).

  The returned array has the values `moving_average_pressure`, `average_pressure` and `average_temperature`.

`BrickletBarometer``#``get_api_version` → [int, int, int]

  Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

`BrickletBarometer``#``get_response_expected`(function_id) → bool

  Parameters: | function_id -- int

  Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

  For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by `#set_response_expected`. For setter functions it is disabled by default and can be enabled.

  Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

  See `#set_response_expected` for the list of function ID constants available for this function.

`BrickletBarometer``#``set_response_expected`(function_id, response_expected) → nil

  Parameters:

  - function_id -- int
  - response_expected -- bool

  Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled and callbacks it is always disabled.

  Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

  The following function ID constants are available for this function:

  - BrickletBarometer::FUNCTION_SET_AIR_PRESSURE_CALLBACK_PERIOD = 3
  - BrickletBarometer::FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 5
  - BrickletBarometer::FUNCTION_SET_AIR_PRESSURE_CALLBACK_THRESHOLD = 7
  - BrickletBarometer::FUNCTION_SET_ALTITUDE_CALLBACK_THRESHOLD = 9
  - BrickletBarometer::FUNCTION_SET_DEBOUNCE_PERIOD = 11
  - BrickletBarometer::FUNCTION_SET_REFERENCE_AIR_PRESSURE = 13
  - BrickletBarometer::FUNCTION_SET_AVERAGING = 20

`BrickletBarometer``#``set_response_expected_all`(response_expected) → nil

  Parameters: | response_expected -- bool

  Changes the response expected flag for all setter and callback configuration functions of this device at once.

`BrickletBarometer``#``get_identity` → [str, str, str, [int, int, int], [int, int, int], int]

  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. There is also a constant for the device identifier of this Bricklet.

  The returned array has the values `uid`, `connected_uid`, `position`, `hardware_version`, `firmware_version` and `device_identifier`.

### Callback Configuration Functions

`BrickletBarometer``#``register_callback`(id) { |param [, ...]| block } → nil

  Parameters: | id -- int

  Registers a callback with ID id to the given block. The available IDs with corresponding function signatures are listed below.

`BrickletBarometer``#``set_air_pressure_callback_period`(period) → nil

  Parameters: | period -- int

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

  `::CALLBACK_AIR_PRESSURE` is only triggered if the air pressure has changed since the last triggering.

  The default value is 0.

`BrickletBarometer``#``get_air_pressure_callback_period` → int

  Returns the period as set by `#set_air_pressure_callback_period`.

`BrickletBarometer``#``set_altitude_callback_period`(period) → nil

  Parameters: | period -- int

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

  `::CALLBACK_ALTITUDE` is only triggered if the altitude has changed since the last triggering.

  The default value is 0.

`BrickletBarometer``#``get_altitude_callback_period` → int

  Returns the period as set by `#set_altitude_callback_period`.

`BrickletBarometer``#``set_air_pressure_callback_threshold`(option, min, max) → nil

  Parameters:

  - option -- str
  - min -- int
  - max -- int

  Sets the thresholds for the `::CALLBACK_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 constants are available for this function:

  - BrickletBarometer::THRESHOLD_OPTION_OFF = 'x'
  - BrickletBarometer::THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletBarometer::THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletBarometer::THRESHOLD_OPTION_SMALLER = '<'
  - BrickletBarometer::THRESHOLD_OPTION_GREATER = '>'

`BrickletBarometer``#``get_air_pressure_callback_threshold` → [str, int, int]

  Returns the threshold as set by `#set_air_pressure_callback_threshold`.

  The following constants are available for this function:

  - BrickletBarometer::THRESHOLD_OPTION_OFF = 'x'
  - BrickletBarometer::THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletBarometer::THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletBarometer::THRESHOLD_OPTION_SMALLER = '<'
  - BrickletBarometer::THRESHOLD_OPTION_GREATER = '>'

  The returned array has the values `option`, `min` and `max`.

`BrickletBarometer``#``set_altitude_callback_threshold`(option, min, max) → nil

  Parameters:

  - option -- str
  - min -- int
  - max -- int

  Sets the thresholds for the `::CALLBACK_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 constants are available for this function:

  - BrickletBarometer::THRESHOLD_OPTION_OFF = 'x'
  - BrickletBarometer::THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletBarometer::THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletBarometer::THRESHOLD_OPTION_SMALLER = '<'
  - BrickletBarometer::THRESHOLD_OPTION_GREATER = '>'

`BrickletBarometer``#``get_altitude_callback_threshold` → [str, int, int]

  Returns the threshold as set by `#set_altitude_callback_threshold`.

  The following constants are available for this function:

  - BrickletBarometer::THRESHOLD_OPTION_OFF = 'x'
  - BrickletBarometer::THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletBarometer::THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletBarometer::THRESHOLD_OPTION_SMALLER = '<'
  - BrickletBarometer::THRESHOLD_OPTION_GREATER = '>'

  The returned array has the values `option`, `min` and `max`.

`BrickletBarometer``#``set_debounce_period`(debounce) → nil

  Parameters: | debounce -- int

  Sets the period in ms with which the threshold callbacks

  - `::CALLBACK_AIR_PRESSURE_REACHED`,
  - `::CALLBACK_ALTITUDE_REACHED`

  are triggered, if the thresholds

  - `#set_air_pressure_callback_threshold`,
  - `#set_altitude_callback_threshold`

  keep being reached.

  The default value is 100.

`BrickletBarometer``#``get_debounce_period` → int

  Returns the debounce period as set by `#set_debounce_period`.

### Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the `#register_callback` function of the device object. The first parameter is the callback ID and the second parameter is a block:

    barometer.register_callback BrickletBarometer::CALLBACK_EXAMPLE, do |param|
      puts "#{param}"
    end

The available constants with inherent number and type of parameters 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.

`BrickletBarometer``::``CALLBACK_AIR_PRESSURE`

  Parameters: | 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.

  `::CALLBACK_AIR_PRESSURE` is only triggered if the air pressure has changed since the last triggering.

`BrickletBarometer``::``CALLBACK_ALTITUDE`

  Parameters: | 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.

  `::CALLBACK_ALTITUDE` is only triggered if the altitude has changed since the last triggering.

`BrickletBarometer``::``CALLBACK_AIR_PRESSURE_REACHED`

  Parameters: | 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`.

`BrickletBarometer``::``CALLBACK_ALTITUDE_REACHED`

  Parameters: | 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`.

### Constants

`BrickletBarometer``::``DEVICE_IDENTIFIER`

  This constant is used to identify a Barometer Bricklet.

  The `#get_identity()` function and the `::CALLBACK_ENUMERATE` callback of the IP Connection have a `device_identifier` parameter to specify the Brick's or Bricklet's type.

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