Modbus - Heart Rate Bricklet – Tinkerforge

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# Modbus - 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 Modbus protocol for the Heart Rate Bricklet. General information and technical specifications for the Heart Rate Bricklet are summarized in its hardware description.

## API

A general description of the Modbus protocol structure can be found here.

### Basic Functions

`BrickletHeartRate.``get_heart_rate`

  Function ID: | 1
  Request: | empty payload

  Response:

  - heart_rate -- uint16

  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_identity`

  Function ID: | 255
  Request: | empty payload

  Response:

  - uid -- char[8]
  - connected_uid -- char[8]
  - position -- char
  - hardware_version -- uint8[3]
  - firmware_version -- uint8[3]
  - device_identifier -- uint16

  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

`BrickletHeartRate.``set_heart_rate_callback_period`

  Function ID: | 2

  Request:

  - period -- uint32

  Response: | no response

  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`

  Function ID: | 3
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_heart_rate_callback_period`.

`BrickletHeartRate.``set_heart_rate_callback_threshold`

  Function ID: | 4

  Request:

  - option -- char
  - min -- uint16
  - max -- uint16

  Response: | no response

  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).

`BrickletHeartRate.``get_heart_rate_callback_threshold`

  Function ID: | 5
  Request: | empty payload

  Response:

  - option -- char
  - min -- uint16
  - max -- uint16

  Returns the threshold as set by `set_heart_rate_callback_threshold`.

`BrickletHeartRate.``set_debounce_period`

  Function ID: | 6

  Request:

  - debounce -- uint32

  Response: | no response

  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`

  Function ID: | 7
  Request: | empty payload

  Response:

  - debounce -- uint32

  Returns the debounce period as set by `set_debounce_period`.

`BrickletHeartRate.``enable_beat_state_changed_callback`

  Function ID: | 11
  Request: | empty payload
  Response: | no response

  Enables the `CALLBACK_BEAT_STATE_CHANGED` callback.

`BrickletHeartRate.``disable_beat_state_changed_callback`

  Function ID: | 12
  Request: | empty payload
  Response: | no response

  Disables the `CALLBACK_BEAT_STATE_CHANGED` callback.

`BrickletHeartRate.``is_beat_state_changed_callback_enabled`

  Function ID: | 13
  Request: | empty payload

  Response:

  - enabled -- bool

  Returns true if the `CALLBACK_BEAT_STATE_CHANGED` callback is enabled.

### Callbacks

`BrickletHeartRate.``CALLBACK_HEART_RATE`

  Function ID: | 8

  Response:

  - heart_rate -- uint16

  This callback is triggered periodically with the period that is set by `set_heart_rate_callback_period`. The response value 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`

  Function ID: | 9

  Response:

  - heart_rate -- uint16

  This callback is triggered when the threshold as set by `set_heart_rate_callback_threshold` is reached. The response value 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`

  Function ID: | 10

  Response:

  - state -- uint8

  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.

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