Ruby - Heart Rate Bricklet – Tinkerforge

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# Ruby - Heart Rate Bricklet

Note

This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.

This is the description of the Ruby API bindings for the Heart Rate Bricklet. General information and technical specifications for the Heart Rate 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_heart_rate'

    include Tinkerforge

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

    ipcon = IPConnection.new # Create IP connection
    hr = BrickletHeartRate.new UID, ipcon # Create device object

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

    # Get current heart rate (in beats per minute)
    hrate = hr.get_heart_rate
    puts "Heart Rate(bpm): #{hrate}"

    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_heart_rate'

    include Tinkerforge

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

    ipcon = IPConnection.new # Create IP connection
    hr = BrickletHeartRate.new UID, ipcon # Create device object

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

    # Set Period for heart rate callback to 1s (1000ms)
    # Note: The callback is only called every second if the
    #       heart rate has changed since the last call!
    hr.set_heart_rate_callback_period 1000

    # Register heart rate callback
    hr.register_callback(BrickletHeartRate::CALLBACK_HEART_RATE) do |hrate|
        puts "Heart Rate(bpm): #{hrate}"
        puts ''
    end

    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_heart_rate'

    include Tinkerforge

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

    ipcon = IPConnection.new # Create IP connection
    hr = BrickletHeartRate.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)
    hr.set_debounce_period 10000

    # Register callback for heart rate reached threshold
    hr.register_callback(BrickletHeartRate::CALLBACK_HEART_RATE_REACHED) do |hrate|
        puts "Heart Rate(bpm): #{hrate}"
        puts ''
    end

    # Configure threshold for heart rate values,
    # Heart Rate : greater than 70
    hr.set_heart_rate_callback_threshold '>', 50, 70

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

## API

All methods listed below are thread-safe.

### Basic Functions

`BrickletHeartRate``::``new`(uid, ipcon) → heart_rate

  Parameters:

  - uid -- str
  - ipcon -- IPConnection

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

      heart_rate = BrickletHeartRate.new 'YOUR_DEVICE_UID', ipcon

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

`BrickletHeartRate``#``get_heart_rate` → int

  Returns the current heart rate measured.

  If you want to get the heart rate periodically, it is recommended to use the callback `::CALLBACK_HEART_RATE` and set the period with `#set_heart_rate_callback_period`.

### Advanced Functions

`BrickletHeartRate``#``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.

`BrickletHeartRate``#``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.

`BrickletHeartRate``#``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:

  - BrickletHeartRate::FUNCTION_SET_HEART_RATE_CALLBACK_PERIOD = 2
  - BrickletHeartRate::FUNCTION_SET_HEART_RATE_CALLBACK_THRESHOLD = 4
  - BrickletHeartRate::FUNCTION_SET_DEBOUNCE_PERIOD = 6
  - BrickletHeartRate::FUNCTION_ENABLE_BEAT_STATE_CHANGED_CALLBACK = 11
  - BrickletHeartRate::FUNCTION_DISABLE_BEAT_STATE_CHANGED_CALLBACK = 12

`BrickletHeartRate``#``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.

`BrickletHeartRate``#``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

`BrickletHeartRate``#``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.

`BrickletHeartRate``#``set_heart_rate_callback_period`(period) → nil

  Parameters: | period -- int

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

  `::CALLBACK_HEART_RATE` is only triggered if the heart rate has changed since the last triggering.

  The default value is 0.

`BrickletHeartRate``#``get_heart_rate_callback_period` → int

  Returns the period as set by `#set_heart_rate_callback_period`.

`BrickletHeartRate``#``set_heart_rate_callback_threshold`(option, min, max) → nil

  Parameters:

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

  Sets the thresholds for the `::CALLBACK_HEART_RATE_REACHED` callback.

  The following options are possible:

  Option | Description
  --- | ---
  'x' | Callback is turned off
  'o' | Callback is triggered when the heart rate is outside the min and max values
  'i' | Callback is triggered when the heart rate is inside the min and max values
  '<' | Callback is triggered when the heart rate is smaller than the min value (max is ignored)
  '>' | Callback is triggered when the heart rate is greater than the min value (max is ignored)

  The default value is ('x', 0, 0).

  The following constants are available for this function:

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

`BrickletHeartRate``#``get_heart_rate_callback_threshold` → [str, int, int]

  Returns the threshold as set by `#set_heart_rate_callback_threshold`.

  The following constants are available for this function:

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

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

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

  Parameters: | debounce -- int

  Sets the period in ms with which the threshold callback

  - `::CALLBACK_HEART_RATE_REACHED`

  is triggered, if the threshold

  - `#set_heart_rate_callback_threshold`

  keeps being reached.

  The default value is 100.

`BrickletHeartRate``#``get_debounce_period` → int

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

`BrickletHeartRate``#``enable_beat_state_changed_callback` → nil

  Enables the `::CALLBACK_BEAT_STATE_CHANGED` callback.

`BrickletHeartRate``#``disable_beat_state_changed_callback` → nil

  Disables the `::CALLBACK_BEAT_STATE_CHANGED` callback.

`BrickletHeartRate``#``is_beat_state_changed_callback_enabled` → bool

  Returns true if the `::CALLBACK_BEAT_STATE_CHANGED` callback is enabled.

### 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:

    heart_rate.register_callback BrickletHeartRate::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.

`BrickletHeartRate``::``CALLBACK_HEART_RATE`

  Parameters: | heart_rate -- int

  This callback is triggered periodically with the period that is set by `#set_heart_rate_callback_period`. The parameter is the heart rate of the sensor.

  `::CALLBACK_HEART_RATE` is only triggered if the heart rate has changed since the last triggering.

`BrickletHeartRate``::``CALLBACK_HEART_RATE_REACHED`

  Parameters: | heart_rate -- int

  This callback is triggered when the threshold as set by `#set_heart_rate_callback_threshold` is reached. The parameter is the heart rate of the sensor.

  If the threshold keeps being reached, the callback is triggered periodically with the period as set by `#set_debounce_period`.

`BrickletHeartRate``::``CALLBACK_BEAT_STATE_CHANGED`

  Parameters: | state -- int

  This callback provides the current heart beat state.It is called every time a heart beat is detected. The state can either be

  - 0 = Falling: The falling edge of a detected heart beat.
  - 1 = Rising: The rising edge of a detected heart beat.

  The following constants are available for this function:

  - BrickletHeartRate::BEAT_STATE_FALLING = 0
  - BrickletHeartRate::BEAT_STATE_RISING = 1

### Constants

`BrickletHeartRate``::``DEVICE_IDENTIFIER`

  This constant is used to identify a Heart Rate 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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