Python - Dual Button Bricklet 2.0

This is the description of the Python 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 Python API bindings is part of their general description.

Examples

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

Callback

Download (example_callback.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Dual Button Bricklet 2.0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_dual_button_v2 import BrickletDualButtonV2

# Callback function for state changed callback
def cb_state_changed(button_l, button_r, led_l, led_r):
    if button_l == BrickletDualButtonV2.BUTTON_STATE_PRESSED:
        print("Left Button: Pressed")
    elif button_l == BrickletDualButtonV2.BUTTON_STATE_RELEASED:
        print("Left Button: Released")

    if button_r == BrickletDualButtonV2.BUTTON_STATE_PRESSED:
        print("Right Button: Pressed")
    elif button_r == BrickletDualButtonV2.BUTTON_STATE_RELEASED:
        print("Right Button: Released")

    print("")

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    db = BrickletDualButtonV2(UID, ipcon) # Create device object

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

    # Register state changed callback to function cb_state_changed
    db.register_callback(db.CALLBACK_STATE_CHANGED, cb_state_changed)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

API

Generally, every method of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:

  • Error.TIMEOUT = -1
  • Error.ALREADY_CONNECTED = -7
  • Error.NOT_CONNECTED = -8
  • Error.INVALID_PARAMETER = -9
  • Error.NOT_SUPPORTED = -10
  • Error.UNKNOWN_ERROR_CODE = -11
  • Error.STREAM_OUT_OF_SYNC = -12

All methods listed below are thread-safe.

Basic Functions

BrickletDualButtonV2(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

dual_button_v2 = BrickletDualButtonV2("YOUR_DEVICE_UID", ipcon)

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

BrickletDualButtonV2.set_led_state(led_l, led_r)
Parameters:
  • led_l -- int
  • led_r -- int
Return type:

None

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 get_led_state() or you can use set_selected_led_state().

The default value is (1, 1).

The following constants are available for this function:

  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButtonV2.LED_STATE_ON = 2
  • BrickletDualButtonV2.LED_STATE_OFF = 3
BrickletDualButtonV2.get_led_state()
Return type:(int, int)

Returns the current state of the LEDs, as set by set_led_state().

The following constants are available for this function:

  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButtonV2.LED_STATE_ON = 2
  • BrickletDualButtonV2.LED_STATE_OFF = 3

The returned namedtuple has the variables led_l and led_r.

BrickletDualButtonV2.get_button_state()
Return type:(int, int)

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

  • 0 = pressed
  • 1 = released

The following constants are available for this function:

  • BrickletDualButtonV2.BUTTON_STATE_PRESSED = 0
  • BrickletDualButtonV2.BUTTON_STATE_RELEASED = 1

The returned namedtuple has the variables button_l and button_r.

Advanced Functions

BrickletDualButtonV2.set_selected_led_state(led, state)
Parameters:
  • led -- int
  • state -- int
Return type:

None

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

The other LED remains untouched.

The following constants are available for this function:

  • BrickletDualButtonV2.LED_LEFT = 0
  • BrickletDualButtonV2.LED_RIGHT = 1
  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButtonV2.LED_STATE_ON = 2
  • BrickletDualButtonV2.LED_STATE_OFF = 3
BrickletDualButtonV2.get_api_version()
Return type:[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.

BrickletDualButtonV2.get_response_expected(function_id)
Parameters:function_id -- int
Return type:bool

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.

BrickletDualButtonV2.set_response_expected(function_id, response_expected)
Parameters:
  • function_id -- int
  • response_expected -- bool
Return type:

None

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.

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:

  • BrickletDualButtonV2.FUNCTION_SET_LED_STATE = 1
  • BrickletDualButtonV2.FUNCTION_SET_SELECTED_LED_STATE = 5
  • BrickletDualButtonV2.FUNCTION_SET_STATE_CHANGED_CALLBACK_CONFIGURATION = 6
  • BrickletDualButtonV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletDualButtonV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletDualButtonV2.FUNCTION_RESET = 243
  • BrickletDualButtonV2.FUNCTION_WRITE_UID = 248
BrickletDualButtonV2.set_response_expected_all(response_expected)
Parameters:response_expected -- bool
Return type:None

Changes the response expected flag for all setter and callback configuration functions of this device at once.

BrickletDualButtonV2.get_spitfp_error_count()
Return type:(int, int, int, 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.

The returned namedtuple has the variables error_count_ack_checksum, error_count_message_checksum, error_count_frame and error_count_overflow.

BrickletDualButtonV2.set_bootloader_mode(mode)
Parameters:mode -- int
Return type:int

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 constants are available for this function:

  • BrickletDualButtonV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletDualButtonV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletDualButtonV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletDualButtonV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletDualButtonV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickletDualButtonV2.BOOTLOADER_STATUS_OK = 0
  • BrickletDualButtonV2.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletDualButtonV2.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletDualButtonV2.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletDualButtonV2.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletDualButtonV2.BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletDualButtonV2.get_bootloader_mode()
Return type:int

Returns the current bootloader mode, see set_bootloader_mode().

The following constants are available for this function:

  • BrickletDualButtonV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletDualButtonV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletDualButtonV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletDualButtonV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletDualButtonV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
BrickletDualButtonV2.set_write_firmware_pointer(pointer)
Parameters:pointer -- int
Return type:None

Sets the firmware pointer for 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.

BrickletDualButtonV2.write_firmware(data)
Parameters:data -- [int, int, ..61x.., int]
Return type:int

Writes 64 Bytes of firmware at the position as written by 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.

BrickletDualButtonV2.set_status_led_config(config)
Parameters:config -- int
Return type:None

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 constants are available for this function:

  • BrickletDualButtonV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletDualButtonV2.STATUS_LED_CONFIG_ON = 1
  • BrickletDualButtonV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDualButtonV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletDualButtonV2.get_status_led_config()
Return type:int

Returns the configuration as set by set_status_led_config()

The following constants are available for this function:

  • BrickletDualButtonV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletDualButtonV2.STATUS_LED_CONFIG_ON = 1
  • BrickletDualButtonV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDualButtonV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletDualButtonV2.get_chip_temperature()
Return type: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.

BrickletDualButtonV2.reset()
Return type:None

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!

BrickletDualButtonV2.write_uid(uid)
Parameters:uid -- int
Return type:None

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.

BrickletDualButtonV2.read_uid()
Return type:int

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

BrickletDualButtonV2.get_identity()
Return type:(str, str, chr, [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 namedtuple has the variables uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

BrickletDualButtonV2.register_callback(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- callable
Return type:

None

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletDualButtonV2.set_state_changed_callback_configuration(enabled)
Parameters:enabled -- bool
Return type:None

If you enable this callback, the CALLBACK_STATE_CHANGED callback is triggered every time a button is pressed/released

By default this callback is disabled.

BrickletDualButtonV2.get_state_changed_callback_configuration()
Return type:bool

Returns the configuration as set by 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 register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

dual_button_v2.register_callback(BrickletDualButtonV2.CALLBACK_EXAMPLE, my_callback)

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.

BrickletDualButtonV2.CALLBACK_STATE_CHANGED
Parameters:
  • button_l -- int
  • button_r -- int
  • led_l -- int
  • led_r -- int

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 set_state_changed_callback_configuration().

The following constants are available for this function:

  • BrickletDualButtonV2.BUTTON_STATE_PRESSED = 0
  • BrickletDualButtonV2.BUTTON_STATE_RELEASED = 1
  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_ON = 0
  • BrickletDualButtonV2.LED_STATE_AUTO_TOGGLE_OFF = 1
  • BrickletDualButtonV2.LED_STATE_ON = 2
  • BrickletDualButtonV2.LED_STATE_OFF = 3

Constants

BrickletDualButtonV2.DEVICE_IDENTIFIER

This constant is used to identify a Dual Button Bricklet 2.0.

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.

BrickletDualButtonV2.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Dual Button Bricklet 2.0.