Python - Distance US Bricklet¶

Simple¶

Download (example_simple.py)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

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

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Distance US Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_distance_us import BrickletDistanceUS

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

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

    # Get current distance value
    distance = dus.get_distance_value()
    print("Distance Value: " + str(distance))

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

Callback¶

Download (example_callback.py)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

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

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Distance US Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_distance_us import BrickletDistanceUS

# Callback function for distance value callback
def cb_distance(distance):
    print("Distance Value: " + str(distance))

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

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

    # Register distance value callback to function cb_distance
    dus.register_callback(dus.CALLBACK_DISTANCE, cb_distance)

    # Set period for distance value callback to 0.2s (200ms)
    # Note: The distance value callback is only called every 0.2 seconds
    #       if the distance value has changed since the last call!
    dus.set_distance_callback_period(200)

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

Threshold¶

Download (example_threshold.py)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32

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

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Distance US Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_distance_us import BrickletDistanceUS

# Callback function for distance value reached callback
def cb_distance_reached(distance):
    print("Distance Value: " + str(distance))

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

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

    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    dus.set_debounce_period(10000)

    # Register distance value reached callback to function cb_distance_reached
    dus.register_callback(dus.CALLBACK_DISTANCE_REACHED, cb_distance_reached)

    # Configure threshold for distance value "smaller than 200"
    dus.set_distance_callback_threshold("<", 200, 0)

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

Basic Functions¶

BrickletDistanceUS(uid, ipcon)¶

Parameters:	uid – Type: str ipcon – Type: IPConnection
Returns:	distance_us – Type: BrickletDistanceUS

Creates an object with the unique device ID uid:

distance_us = BrickletDistanceUS("YOUR_DEVICE_UID", ipcon)

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

BrickletDistanceUS.get_distance_value()¶

Returns:	distance – Type: int, Range: [0 to 212 - 1]

Returns the current distance value measured by the sensor. A small value corresponds to a small distance, a big value corresponds to a big distance. The relation between the measured distance value and the actual distance is affected by the 5V supply voltage (deviations in the supply voltage result in deviations in the distance values) and is non-linear (resolution is bigger at close range).

If you want to get the distance value periodically, it is recommended to use the CALLBACK_DISTANCE callback and set the period with set_distance_callback_period().

Advanced Functions¶

BrickletDistanceUS.set_moving_average(average)¶

Parameters:	average – Type: int, Range: [0 to 100], Default: 20
Returns:	None

Sets the length of a moving averaging for the distance value.

Setting the length to 0 will turn the averaging completely off. With less averaging, there is more noise on the data.

BrickletDistanceUS.get_moving_average()¶

Returns:	average – Type: int, Range: [0 to 100], Default: 20

Returns the length moving average as set by set_moving_average().

BrickletDistanceUS.get_identity()¶

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]

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¶

BrickletDistanceUS.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.

BrickletDistanceUS.set_distance_callback_period(period)¶

Parameters:	period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Returns:	None

Sets the period with which the CALLBACK_DISTANCE callback is triggered periodically. A value of 0 turns the callback off.

Der CALLBACK_DISTANCE callback is only triggered if the distance value has changed since the last triggering.

BrickletDistanceUS.get_distance_callback_period()¶

Returns:	period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_distance_callback_period().

BrickletDistanceUS.set_distance_callback_threshold(option, min, max)¶

Parameters:	option – Type: chr, Range: See constants, Default: "x" min – Type: int, Range: [0 to 212 - 1] max – Type: int, Range: [0 to 212 - 1]
Returns:	None

Sets the thresholds for the CALLBACK_DISTANCE_REACHED callback.

The following options are possible:

Option	Description
'x'	Callback is turned off
'o'	Callback is triggered when the distance value is outside the min and max values
'i'	Callback is triggered when the distance value is inside the min and max values
'<'	Callback is triggered when the distance value is smaller than the min value (max is ignored)
'>'	Callback is triggered when the distance value is greater than the min value (max is ignored)

The following constants are available for this function:

For option:

• BrickletDistanceUS.THRESHOLD_OPTION_OFF = "x"
• BrickletDistanceUS.THRESHOLD_OPTION_OUTSIDE = "o"
• BrickletDistanceUS.THRESHOLD_OPTION_INSIDE = "i"
• BrickletDistanceUS.THRESHOLD_OPTION_SMALLER = "<"
• BrickletDistanceUS.THRESHOLD_OPTION_GREATER = ">"

BrickletDistanceUS.get_distance_callback_threshold()¶

Return Object:	option – Type: chr, Range: See constants, Default: "x" min – Type: int, Range: [0 to 212 - 1] max – Type: int, Range: [0 to 212 - 1]

Returns the threshold as set by set_distance_callback_threshold().

The following constants are available for this function:

For option:

• BrickletDistanceUS.THRESHOLD_OPTION_OFF = "x"
• BrickletDistanceUS.THRESHOLD_OPTION_OUTSIDE = "o"
• BrickletDistanceUS.THRESHOLD_OPTION_INSIDE = "i"
• BrickletDistanceUS.THRESHOLD_OPTION_SMALLER = "<"
• BrickletDistanceUS.THRESHOLD_OPTION_GREATER = ">"

BrickletDistanceUS.set_debounce_period(debounce)¶

Parameters:	debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100
Returns:	None

Sets the period with which the threshold callbacks

• CALLBACK_DISTANCE_REACHED,

are triggered, if the thresholds

• set_distance_callback_threshold(),

keep being reached.

BrickletDistanceUS.get_debounce_period()¶

Returns:	debounce – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Returns the debounce period as set by set_debounce_period().

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)

distance_us.register_callback(BrickletDistanceUS.CALLBACK_EXAMPLE, my_callback)

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

BrickletDistanceUS.CALLBACK_DISTANCE¶

Callback Parameters:	distance – Type: int, Range: [0 to 212 - 1]

This callback is triggered periodically with the period that is set by set_distance_callback_period(). The parameter is the distance value of the sensor.

The CALLBACK_DISTANCE callback is only triggered if the distance value has changed since the last triggering.

BrickletDistanceUS.CALLBACK_DISTANCE_REACHED¶

Callback Parameters:	distance – Type: int, Range: [0 to 212 - 1]

This callback is triggered when the threshold as set by set_distance_callback_threshold() is reached. The parameter is the distance value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by set_debounce_period().

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.

BrickletDistanceUS.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.

BrickletDistanceUS.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:

• BrickletDistanceUS.FUNCTION_SET_DISTANCE_CALLBACK_PERIOD = 2
• BrickletDistanceUS.FUNCTION_SET_DISTANCE_CALLBACK_THRESHOLD = 4
• BrickletDistanceUS.FUNCTION_SET_DEBOUNCE_PERIOD = 6
• BrickletDistanceUS.FUNCTION_SET_MOVING_AVERAGE = 10

BrickletDistanceUS.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.

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:

• BrickletDistanceUS.FUNCTION_SET_DISTANCE_CALLBACK_PERIOD = 2
• BrickletDistanceUS.FUNCTION_SET_DISTANCE_CALLBACK_THRESHOLD = 4
• BrickletDistanceUS.FUNCTION_SET_DEBOUNCE_PERIOD = 6
• BrickletDistanceUS.FUNCTION_SET_MOVING_AVERAGE = 10

BrickletDistanceUS.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¶

BrickletDistanceUS.DEVICE_IDENTIFIER¶

This constant is used to identify a Distance US 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.

BrickletDistanceUS.DEVICE_DISPLAY_NAME¶

This constant represents the human readable name of a Distance US Bricklet.