Python - Dual Button Bricklet¶

This is the description of the Python 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 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)

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

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

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_dual_button import BrickletDualButton

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

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

    print("")

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    db = BrickletDualButton(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)

    input("Press key to exit\n") # Use raw_input() in Python 2
    ipcon.disconnect()

API¶

Generally, every function 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.NOT_ADDED = -6 (unused since Python bindings version 2.0.0)
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
Error.INVALID_UID = -13
Error.NON_ASCII_CHAR_IN_SECRET = -14
Error.WRONG_DEVICE_TYPE = -15
Error.DEVICE_REPLACED = -16
Error.WRONG_RESPONSE_LENGTH = -17

All functions listed below are thread-safe.

Basic Functions¶

BrickletDualButton(uid, ipcon)¶

Parameters:	uid – Type: str ipcon – Type: IPConnection
Returns:	dual_button – Type: BrickletDualButton

Creates an object with the unique device ID uid:

dual_button = BrickletDualButton("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected.

BrickletDualButton.set_led_state(led_l, led_r)¶

Parameters:	led_l – Type: int, Range: See constants, Default: 1 led_r – Type: int, Range: See constants, Default: 1
Returns:	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 following constants are available for this function:

For led_l:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

For led_r:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

BrickletDualButton.get_led_state()¶

Return Object:	led_l – Type: int, Range: See constants, Default: 1 led_r – Type: int, Range: See constants, Default: 1

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

The following constants are available for this function:

For led_l:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

For led_r:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

BrickletDualButton.get_button_state()¶

Return Object:	button_l – Type: int, Range: See constants button_r – Type: int, Range: See constants

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

0 = pressed
1 = released

The following constants are available for this function:

For button_l:

BrickletDualButton.BUTTON_STATE_PRESSED = 0
BrickletDualButton.BUTTON_STATE_RELEASED = 1

For button_r:

BrickletDualButton.BUTTON_STATE_PRESSED = 0
BrickletDualButton.BUTTON_STATE_RELEASED = 1

Advanced Functions¶

BrickletDualButton.set_selected_led_state(led, state)¶

Parameters:	led – Type: int, Range: See constants state – Type: int, Range: See constants
Returns:	None

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

The other LED remains untouched.

The following constants are available for this function:

For led:

BrickletDualButton.LED_LEFT = 0
BrickletDualButton.LED_RIGHT = 1

For state:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

BrickletDualButton.get_identity()¶

Return Object:

Return Object:	uid – Type: str, Length: up to 8 connected_uid – Type: str, Length: up to 8 position – Type: chr, Range: ["a" to "h", "z"] hardware_version – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255] firmware_version – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255] device_identifier – Type: int, Range: [0 to 2¹⁶ - 1]

uid – Type: str, Length: up to 8
connected_uid – Type: str, Length: up to 8
position – Type: chr, Range: ["a" to "h", "z"]
hardware_version – Type: [int, ...], Length: 3

0: major – Type: int, Range: [0 to 255]
1: minor – Type: int, Range: [0 to 255]
2: revision – Type: int, Range: [0 to 255]

firmware_version – Type: [int, ...], Length: 3

0: major – Type: int, Range: [0 to 255]
1: minor – Type: int, Range: [0 to 255]
2: revision – Type: int, Range: [0 to 255]

device_identifier – Type: int, Range: [0 to 2¹⁶ - 1]

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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions¶

BrickletDualButton.register_callback(callback_id, function)¶

Parameters:	callback_id – Type: int function – Type: callable
Returns:	None

Registers the given function with the given callback_id.

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

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.register_callback(BrickletDualButton.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.

BrickletDualButton.CALLBACK_STATE_CHANGED¶

Callback Parameters:	button_l – Type: int, Range: See constants button_r – Type: int, Range: See constants led_l – Type: int, Range: See constants led_r – Type: int, Range: See constants

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 constants are available for this function:

For button_l:

BrickletDualButton.BUTTON_STATE_PRESSED = 0
BrickletDualButton.BUTTON_STATE_RELEASED = 1

For button_r:

BrickletDualButton.BUTTON_STATE_PRESSED = 0
BrickletDualButton.BUTTON_STATE_RELEASED = 1

For led_l:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

For led_r:

BrickletDualButton.LED_STATE_AUTO_TOGGLE_ON = 0
BrickletDualButton.LED_STATE_AUTO_TOGGLE_OFF = 1
BrickletDualButton.LED_STATE_ON = 2
BrickletDualButton.LED_STATE_OFF = 3

Virtual Functions¶

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

BrickletDualButton.get_api_version()¶

Return Object:	api_version – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255]

Returns the version of the API definition 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.

BrickletDualButton.get_response_expected(function_id)¶

Parameters:	function_id – Type: int, Range: See constants
Returns:	response_expected – 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

BrickletDualButton.FUNCTION_SET_LED_STATE = 1
BrickletDualButton.FUNCTION_SET_SELECTED_LED_STATE = 5

BrickletDualButton.set_response_expected(function_id, response_expected)¶

Parameters:	function_id – Type: int, Range: See constants response_expected – Type: bool
Returns:	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.

The following constants are available for this function:

For function_id:

BrickletDualButton.FUNCTION_SET_LED_STATE = 1
BrickletDualButton.FUNCTION_SET_SELECTED_LED_STATE = 5

BrickletDualButton.set_response_expected_all(response_expected)¶

Parameters:	response_expected – Type: bool
Returns:	None

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

Constants¶

BrickletDualButton.DEVICE_IDENTIFIER¶

This constant is used to identify a Dual Button Bricklet.

The get_identity() function and the IPConnection.CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletDualButton.DEVICE_DISPLAY_NAME¶: This constant represents the human readable name of a Dual Button Bricklet.