Python - IP Connection

This is the description of the Python API bindings for the IP Connection. The IP Connection manages the communication between the API bindings and the Brick Daemon or a WIFI/Ethernet Extension. Before Bricks and Bricklets can be controlled using their API an IP Connection has to be created and its TCP/IP connection has to be established.

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).

Enumerate

Download (example_enumerate.py)

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

HOST = "localhost"
PORT = 4223

from tinkerforge.ip_connection import IPConnection

# Print incoming enumeration
def cb_enumerate(uid, connected_uid, position, hardware_version, firmware_version,
                 device_identifier, enumeration_type):
    print("UID:               " + uid)
    print("Enumeration Type:  " + str(enumeration_type))

    if enumeration_type == IPConnection.ENUMERATION_TYPE_DISCONNECTED:
        print("")
        return

    print("Connected UID:     " + connected_uid)
    print("Position:          " + position)
    print("Hardware Version:  " + str(hardware_version))
    print("Firmware Version:  " + str(firmware_version))
    print("Device Identifier: " + str(device_identifier))
    print("")

if __name__ == "__main__":
    # Create connection and connect to brickd
    ipcon = IPConnection()
    ipcon.connect(HOST, PORT)

    # Register Enumerate Callback
    ipcon.register_callback(IPConnection.CALLBACK_ENUMERATE, cb_enumerate)

    # Trigger Enumerate
    ipcon.enumerate()

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

Authenticate

Download (example_authenticate.py)

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

HOST = "localhost"
PORT = 4223
SECRET = "My Authentication Secret!"

from tinkerforge.ip_connection import IPConnection

# Authenticate each time the connection got (re-)established
def cb_connected(connect_reason):
    if connect_reason == IPConnection.CONNECT_REASON_REQUEST:
        print("Connected by request")
    elif connect_reason == IPConnection.CONNECT_REASON_AUTO_RECONNECT:
        print("Auto-Reconnect")

    # Authenticate first...
    try:
        ipcon.authenticate(SECRET)
        print("Authentication succeeded")
    except:
        print("Could not authenticate")
        return

    # ...then trigger enumerate
    ipcon.enumerate()

# Print incoming enumeration
def cb_enumerate(uid, connected_uid, position, hardware_version, firmware_version,
                 device_identifier, enumeration_type):
    print("UID: " + uid + ", Enumeration Type: " + str(enumeration_type))

if __name__ == "__main__":
    # Create IPConnection
    ipcon = IPConnection()

    # Register Connected Callback
    ipcon.register_callback(IPConnection.CALLBACK_CONNECTED, cb_connected)

    # Register Enumerate Callback
    ipcon.register_callback(IPConnection.CALLBACK_ENUMERATE, cb_enumerate)

    # Connect to brickd
    ipcon.connect(HOST, PORT)

    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

All methods listed below are thread-safe.

Basic Functions

IPConnection()

Creates an IP Connection object that can be used to enumerate the available devices. It is also required for the constructor of Bricks and Bricklets.

IPConnection.connect(host, port)
Parameters:
  • host -- str
  • port -- int
Return type:

None

Creates a TCP/IP connection to the given host and port. The host and port can refer to a Brick Daemon or to a WIFI/Ethernet Extension.

Devices can only be controlled when the connection was established successfully.

Blocks until the connection is established and throws an exception if there is no Brick Daemon or WIFI/Ethernet Extension listening at the given host and port.

IPConnection.disconnect()
Return type:None

Disconnects the TCP/IP connection from the Brick Daemon or the WIFI/Ethernet Extension.

IPConnection.authenticate(secret)
Parameters:secret -- str
Return type:None

Performs an authentication handshake with the connected Brick Daemon or WIFI/Ethernet Extension. If the handshake succeeds the connection switches from non-authenticated to authenticated state and communication can continue as normal. If the handshake fails then the connection gets closed. Authentication can fail if the wrong secret was used or if authentication is not enabled at all on the Brick Daemon or the WIFI/Ethernet Extension.

See the authentication tutorial for more information.

New in version 2.1.0.

IPConnection.get_connection_state()
Return type:int

Can return the following states:

  • IPConnection.CONNECTION_STATE_DISCONNECTED (0): No connection is established.
  • IPConnection.CONNECTION_STATE_CONNECTED (1): A connection to the Brick Daemon or the WIFI/Ethernet Extension is established.
  • IPConnection.CONNECTION_STATE_PENDING (2): IP Connection is currently trying to connect.
IPConnection.set_auto_reconnect(auto_reconnect)
Parameters:auto_reconnect -- bool
Return type:None

Enables or disables auto-reconnect. If auto-reconnect is enabled, the IP Connection will try to reconnect to the previously given host and port, if the currently existing connection is lost. Therefore, auto-reconnect only does something after a successful connect() call.

Default value is True.

IPConnection.get_auto_reconnect()
Return type:bool

Returns True if auto-reconnect is enabled, False otherwise.

IPConnection.set_timeout(timeout)
Parameters:timeout -- float
Return type:None

Sets the timeout in seconds for getters and for setters for which the response expected flag is activated.

Default timeout is 2.5.

IPConnection.get_timeout()
Return type:float

Returns the timeout as set by set_timeout().

IPConnection.enumerate()
Return type:None

Broadcasts an enumerate request. All devices will respond with an enumerate callback.

IPConnection.wait()
Return type:None

Stops the current thread until unwait() is called.

This is useful if you rely solely on callbacks for events, if you want to wait for a specific callback or if the IP Connection was created in a thread.

wait and unwait act in the same way as acquire and release of a semaphore.

IPConnection.unwait()
Return type:None

Unwaits the thread previously stopped by wait()

wait and unwait act in the same way as acquire and release of a semaphore.

Callback Configuration Functions

IPConnection.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 described below.

Callbacks

Callbacks can be registered to be notified about events. The registration is done with the register_callback() function. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

ipcon.register_callback(IPConnection.CALLBACK_EXAMPLE, my_callback)

The available constants with inherent number and type of parameters are described below.

IPConnection.CALLBACK_ENUMERATE
Parameters:
  • uid -- str
  • connected_uid -- str
  • position -- chr
  • hardware_version -- [int, int, int]
  • firmware_version -- [int, int, int]
  • device_identifier -- int
  • enumeration_type -- int

The callback has seven parameters:

  • uid: The UID of the device.
  • connected_uid: UID where the device is connected to. For a Bricklet this will be a UID of the Brick where it is connected to. For a Brick it will be the UID of the bottom Master Brick in the stack. For the bottom Master Brick in a stack this will be "0". With this information it is possible to reconstruct the complete network topology.
  • position: For Bricks: '0' - '8' (position in stack). For Bricklets: 'a' - 'd' (position on Brick).
  • hardware_version: Major, minor and release number for hardware version.
  • firmware_version: Major, minor and release number for firmware version.
  • device_identifier: A number that represents the device.
  • enumeration_type: Type of enumeration.

Possible enumeration types are:

  • IPConnection.ENUMERATION_TYPE_AVAILABLE (0): Device is available (enumeration triggered by user: enumerate()). This enumeration type can occur multiple times for the same device.
  • IPConnection.ENUMERATION_TYPE_CONNECTED (1): Device is newly connected (automatically send by Brick after establishing a communication connection). This indicates that the device has potentially lost its previous configuration and needs to be reconfigured.
  • IPConnection.ENUMERATION_TYPE_DISCONNECTED (2): Device is disconnected (only possible for USB connection). In this case only uid and enumeration_type are valid.

It should be possible to implement plug-and-play functionality with this (as is done in Brick Viewer).

The device identifier numbers can be found here. There are also constants for these numbers named following this pattern:

<device-class>.DEVICE_IDENTIFIER

For example: Master.DEVICE_IDENTIFIER or AmbientLight.DEVICE_IDENTIFIER.

IPConnection.CALLBACK_CONNECTED
Parameters:connect_reason -- int

This callback is called whenever the IP Connection got connected to a Brick Daemon or to a WIFI/Ethernet Extension, possible reasons are:

  • IPConnection.CONNECT_REASON_REQUEST (0): Connection established after request from user.
  • IPConnection.CONNECT_REASON_AUTO_RECONNECT (1): Connection after auto-reconnect.
IPConnection.CALLBACK_DISCONNECTED
Parameters:disconnect_reason -- int

This callback is called whenever the IP Connection got disconnected from a Brick Daemon or from a WIFI/Ethernet Extension, possible reasons are:

  • IPConnection.DISCONNECT_REASON_REQUEST (0): Disconnect was requested by user.
  • IPConnection.DISCONNECT_REASON_ERROR (1): Disconnect because of an unresolvable error.
  • IPConnection.DISCONNECT_REASON_SHUTDOWN (2): Disconnect initiated by Brick Daemon or WIFI/Ethernet Extension.