MQTT - Dual Button Bricklet

This is the description of the MQTT API bindings for the Dual Button Bricklet. General information and technical specifications for the Dual Button Bricklet are summarized in its hardware description.

An installation guide for the MQTT API bindings is part of their general description.

Examples

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

Callback

Download (example-callback.txt)

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# Change XYZ to the UID of your Dual Button Bricklet

setup:
    # Handle incoming state changed callbacks
    subscribe to tinkerforge/callback/dual_button_bricklet/XYZ/state_changed
    publish '{"register": true}' to tinkerforge/register/dual_button_bricklet/XYZ/state_changed # Register state_changed callback

API

All published payloads to and from the MQTT bindings are in JSON format.

If an error occures, the bindings publish a JSON object containing the error message as attribute "_ERROR". It is published on the corresponding response topic: .../response/... for .../request/... and .../callback/... for .../register/....

Basic Functions

request/dual_button_bricklet/<UID>/set_led_state
Request payload:
 
  • led_l -- int (has symbols)
  • led_r -- int (has symbols)

Sets the state of the LEDs. Possible states are:

  • 0 = AutoToggleOn: Enables auto toggle with initially enabled LED.
  • 1 = AutoToggleOff: Activates auto toggle with initially disabled LED.
  • 2 = On: Enables LED (auto toggle is disabled).
  • 3 = Off: Disables LED (auto toggle is disabled).

In auto toggle mode the LED is toggled automatically at each press of a button.

If you just want to set one of the LEDs and don't know the current state of the other LED, you can get the state with request/dual_button_bricklet/<UID>/get_led_state or you can use request/dual_button_bricklet/<UID>/set_selected_led_state.

The default value is (1, 1).

The following symbols are available for this function:

for led_l:

  • "AutoToggleOn" = 0
  • "AutoToggleOff" = 1
  • "On" = 2
  • "Off" = 3
request/dual_button_bricklet/<UID>/get_led_state
Response payload:
 
  • led_l -- int (has symbols)
  • led_r -- int (has symbols)

Returns the current state of the LEDs, as set by request/dual_button_bricklet/<UID>/set_led_state.

The following symbols are available for this function:

for led_l:

  • "AutoToggleOn" = 0
  • "AutoToggleOff" = 1
  • "On" = 2
  • "Off" = 3
request/dual_button_bricklet/<UID>/get_button_state
Response payload:
 
  • button_l -- int (has symbols)
  • button_r -- int (has symbols)

Returns the current state for both buttons. Possible states are:

  • 0 = pressed
  • 1 = released

The following symbols are available for this function:

for button_l:

  • "Pressed" = 0
  • "Released" = 1

Advanced Functions

request/dual_button_bricklet/<UID>/set_selected_led_state
Request payload:
 
  • led -- int (has symbols)
  • state -- int (has symbols)

Sets the state of the selected LED (0 or 1).

The other LED remains untouched.

The following symbols are available for this function:

for led:

  • "Left" = 0
  • "Right" = 1

for state:

  • "AutoToggleOn" = 0
  • "AutoToggleOff" = 1
  • "On" = 2
  • "Off" = 3
request/dual_button_bricklet/<UID>/get_identity
Response payload:
 
  • uid -- string
  • connected_uid -- string
  • position -- string
  • hardware_version -- [int,int,int]
  • firmware_version -- [int,int,int]
  • device_identifier -- int (has symbols)
  • _display_name -- string

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. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.

The display name contains the Dual Button's name in a human readable form.

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the corresponding .../register/... topic and an optional suffix. This suffix can be used to deregister the callback later.

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.

register/dual_button_bricklet/<UID>/state_changed
Request payload:
 
  • register -- bool
Response payload:
 
  • button_l -- int (has symbols)
  • button_r -- int (has symbols)
  • led_l -- int (has symbols)
  • led_r -- int (has symbols)

A callback can be registered for this event by publishing to the .../register/dual_button_bricklet/<UID>/state_changed[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/dual_button_bricklet/<UID>/state_changed[/<SUFFIX>] topic for each registered suffix.

This callback is called whenever a button is pressed.

Possible states for buttons are:

  • 0 = pressed
  • 1 = released

Possible states for LEDs are:

  • 0 = AutoToggleOn: Auto toggle enabled and LED on.
  • 1 = AutoToggleOff: Auto toggle enabled and LED off.
  • 2 = On: LED on (auto toggle is disabled).
  • 3 = Off: LED off (auto toggle is disabled).

The following symbols are available for this function:

for button_l:

  • "Pressed" = 0
  • "Released" = 1

for led_l:

  • "AutoToggleOn" = 0
  • "AutoToggleOff" = 1
  • "On" = 2
  • "Off" = 3