Python - Motion Detector Bricklet

This is the description of the Python API bindings for the Motion Detector Bricklet. General information and technical specifications for the Motion Detector 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)

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

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Motion Detector Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_motion_detector import BrickletMotionDetector

# Callback function for motion detected callback
def cb_motion_detected():
    print("Motion Detected")

# Callback function for detection cycle ended callback
def cb_detection_cycle_ended():
    print("Detection Cycle Ended (next detection possible in ~3 seconds)")

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

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

    # Register motion detected callback to function cb_motion_detected
    md.register_callback(md.CALLBACK_MOTION_DETECTED, cb_motion_detected)

    # Register detection cycle ended callback to function cb_detection_cycle_ended
    md.register_callback(md.CALLBACK_DETECTION_CYCLE_ENDED, cb_detection_cycle_ended)

    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

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

Creates an object with the unique device ID uid:

motion_detector = BrickletMotionDetector("YOUR_DEVICE_UID", ipcon)

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

BrickletMotionDetector.get_motion_detected()
Return type:int

Returns 1 if a motion was detected. How long this returns 1 after a motion was detected can be adjusted with one of the small potentiometers on the Motion Detector Bricklet, see here.

There is also a blue LED on the Bricklet that is on as long as the Bricklet is in the "motion detected" state.

The following constants are available for this function:

  • BrickletMotionDetector.MOTION_NOT_DETECTED = 0
  • BrickletMotionDetector.MOTION_DETECTED = 1

Advanced Functions

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

Sets the status led configuration.

By default the status LED turns on if a motion is detected and off is no motion is detected.

You can also turn the LED permanently on/off.

The following constants are available for this function:

  • BrickletMotionDetector.STATUS_LED_CONFIG_OFF = 0
  • BrickletMotionDetector.STATUS_LED_CONFIG_ON = 1
  • BrickletMotionDetector.STATUS_LED_CONFIG_SHOW_STATUS = 2

New in version 2.0.1 (Plugin).

BrickletMotionDetector.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:

  • BrickletMotionDetector.STATUS_LED_CONFIG_OFF = 0
  • BrickletMotionDetector.STATUS_LED_CONFIG_ON = 1
  • BrickletMotionDetector.STATUS_LED_CONFIG_SHOW_STATUS = 2

New in version 2.0.1 (Plugin).

BrickletMotionDetector.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.

BrickletMotionDetector.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.

BrickletMotionDetector.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:

  • BrickletMotionDetector.FUNCTION_SET_STATUS_LED_CONFIG = 4
BrickletMotionDetector.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.

BrickletMotionDetector.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

BrickletMotionDetector.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.

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)

motion_detector.register_callback(BrickletMotionDetector.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.

BrickletMotionDetector.CALLBACK_MOTION_DETECTED

This callback is called after a motion was detected.

BrickletMotionDetector.CALLBACK_DETECTION_CYCLE_ENDED

This callback is called when the detection cycle ended. When this callback is called, a new motion can be detected again after approximately 2 seconds.

Constants

BrickletMotionDetector.DEVICE_IDENTIFIER

This constant is used to identify a Motion Detector Bricklet.

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.

BrickletMotionDetector.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Motion Detector Bricklet.