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

is triggered, if the 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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