MQTT - Dual Button Bricklet 2.0

This is the description of the MQTT API bindings for the Dual Button Bricklet 2.0. General information and technical specifications for the Dual Button Bricklet 2.0 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 2.0

setup:
    # Handle incoming state changed callbacks
    subscribe to tinkerforge/callback/dual_button_v2_bricklet/XYZ/state_changed
    publish '{"register": true}' to tinkerforge/register/dual_button_v2_bricklet/XYZ/state_changed # Register state_changed callback

API

All published payload to an from the MQTT bindings is in the 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_v2_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_v2_bricklet/<UID>/get_led_state or you can use request/dual_button_v2_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_v2_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_v2_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_v2_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_v2_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_v2_bricklet/<UID>/get_spitfp_error_count
Response payload:
 
  • error_count_ack_checksum -- int
  • error_count_message_checksum -- int
  • error_count_frame -- int
  • error_count_overflow -- int

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

request/dual_button_v2_bricklet/<UID>/set_bootloader_mode
Request payload:
 
  • mode -- int (has symbols)
Response payload:
 
  • status -- int (has symbols)

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following symbols are available for this function:

for mode:

  • "Bootloader" = 0
  • "Firmware" = 1
  • "BootloaderWaitForReboot" = 2
  • "FirmwareWaitForReboot" = 3
  • "FirmwareWaitForEraseAndReboot" = 4

for status:

  • "OK" = 0
  • "InvalidMode" = 1
  • "NoChange" = 2
  • "EntryFunctionNotPresent" = 3
  • "DeviceIdentifierIncorrect" = 4
  • "CRCMismatch" = 5
request/dual_button_v2_bricklet/<UID>/get_bootloader_mode
Response payload:
 
  • mode -- int (has symbols)

Returns the current bootloader mode, see request/dual_button_v2_bricklet/<UID>/set_bootloader_mode.

The following symbols are available for this function:

for mode:

  • "Bootloader" = 0
  • "Firmware" = 1
  • "BootloaderWaitForReboot" = 2
  • "FirmwareWaitForReboot" = 3
  • "FirmwareWaitForEraseAndReboot" = 4
request/dual_button_v2_bricklet/<UID>/set_write_firmware_pointer
Request payload:
 
  • pointer -- int

Sets the firmware pointer for request/dual_button_v2_bricklet/<UID>/write_firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

request/dual_button_v2_bricklet/<UID>/write_firmware
Request payload:
 
  • data -- [int,... (x64)]
Response payload:
 
  • status -- int

Writes 64 Bytes of firmware at the position as written by request/dual_button_v2_bricklet/<UID>/set_write_firmware_pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

request/dual_button_v2_bricklet/<UID>/set_status_led_config
Request payload:
 
  • config -- int (has symbols)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/dual_button_v2_bricklet/<UID>/get_status_led_config
Response payload:
 
  • config -- int (has symbols)

Returns the configuration as set by request/dual_button_v2_bricklet/<UID>/set_status_led_config

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/dual_button_v2_bricklet/<UID>/get_chip_temperature
Response payload:
 
  • temperature -- int

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

request/dual_button_v2_bricklet/<UID>/reset

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

request/dual_button_v2_bricklet/<UID>/write_uid
Request payload:
 
  • uid -- int

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

request/dual_button_v2_bricklet/<UID>/read_uid
Response payload:
 
  • uid -- int

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

request/dual_button_v2_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 2.0's name in a human readable form.

Callback Configuration Functions

request/dual_button_v2_bricklet/<UID>/set_state_changed_callback_configuration
Request payload:
 
  • enabled -- bool

If you enable this callback, the register/dual_button_v2_bricklet/<UID>/state_changed callback is triggered every time a button is pressed/released

By default this callback is disabled.

request/dual_button_v2_bricklet/<UID>/get_state_changed_callback_configuration
Response payload:
 
  • enabled -- bool

Returns the configuration as set by request/dual_button_v2_bricklet/<UID>/set_state_changed_callback_configuration.

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_v2_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_v2_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_v2_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).

This callback can be enabled with request/dual_button_v2_bricklet/<UID>/set_state_changed_callback_configuration.

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