Note
This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.
This is the description of the Python API bindings for the Accelerometer Bricklet. General information and technical specifications for the Accelerometer Bricklet are summarized in its hardware description.
An installation guide for the Python API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
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 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "abc" # Change to your UID
import time
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_accelerometer import Accelerometer
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
acc = Accelerometer(UID, ipcon) # Create device object
ipcon.connect(HOST, PORT) # Connect to brickd
# Don't use device before ipcon is connected
# Get Acceleration (unit is 1/1000 G)
acceleration = acc.get_acceleration()
print('Acceleration: x -> {0}G, y -> {1}G, z -> {2}G'.format(acceleration.x / 1000.0,
acceleration.y / 1000.0,
acceleration.z / 1000.0))
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
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 32 33 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "abc" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_accelerometer import Accelerometer
# Callback function for acceleration callback
def cb_acceleration(x, y, z):
print('Acceleration: x -> {0}G, y -> {1}G, z -> {2}G'.format(x / 1000.0,
y / 1000.0,
z / 1000.0))
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
acc = Accelerometer(UID, ipcon) # Create device object
ipcon.connect(HOST, PORT) # Connect to brickd
# Don't use device before ipcon is connected
# Set Period for acceleration callback to 0.1s (100ms)
# Note: The callback is only called every second if the
# acceleration has changed since the last call!
acc.set_acceleration_callback_period(100)
# Register acceleration callback to function cb_acceleration
acc.register_callback(acc.CALLBACK_ACCELERATION, cb_acceleration)
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
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 33 34 35 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "abc" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_accelerometer import Accelerometer
# Callback function for acceleration callback
# Turn LED on if acceleration goes above 3G
def cb_reached(acc, x, y, z):
acc.led_on()
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
acc = Accelerometer(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 1 seconds (1000ms)
acc.set_debounce_period(1000)
# Register threshold reached callback to function cb_reached
func = lambda x, y, z: cb_reached(acc, x, y, z)
acc.register_callback(acc.CALLBACK_ACCELERATION_REACHED, func)
# Configure threshold for acceleration values,
# Trigger callback if one of the accelerations goes above 3G
acc.set_acceleration_callback_threshold('>', 3000, 0, 3000, 0, 3000, 0)
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
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:
All methods listed below are thread-safe.
Parameters: |
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Creates an object with the unique device ID uid:
accelerometer = Accelerometer("YOUR_DEVICE_UID", ipcon)
This object can then be used after the IP Connection is connected (see examples above).
Return type: | (int, int, int) |
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Returns the acceleration in x, y and z direction. The values are given in mG (1/1000 G).
If you want to get the acceleration periodically, it is recommended to use the callback CALLBACK_ACCELERATION and set the period with set_acceleration_callback_period().
The returned namedtuple has the variables x, y and z.
Return type: | int |
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Returns the temperature of the accelerometer in °C.
Return type: | None |
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Enables the LED on the Bricklet.
Return type: | None |
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Disables the LED on the Bricklet.
Return type: | int |
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Returns true if the LED is enabled, false otherwise.
Parameters: |
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Return type: | None |
Configures the data rate, full scale range and filter bandwidth. Possible values are:
Decreasing data rate or full scale range will also decrease the noise on the data.
The default values are 100Hz data rate, -4G to +4G range and 200Hz filter bandwidth.
The following constants are available for this function:
Return type: | (int, int, int) |
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Returns the configuration as set by set_configuration().
The following constants are available for this function:
The returned namedtuple has the variables data_rate, full_scale and filter_bandwidth.
Return type: | [int, int, int] |
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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.
Parameters: | function_id -- int |
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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.
Parameters: |
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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 and callbacks it is always disabled.
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:
Parameters: | response_expected -- bool |
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Return type: | None |
Changes the response expected flag for all setter and callback configuration functions of this device at once.
Return type: | (str, str, chr, [int, int, int], [int, int, int], int) |
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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.
Parameters: |
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Return type: | None |
Registers a callback with ID id to the function callback. The available IDs with corresponding function signatures are listed below.
Parameters: | period -- int |
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Return type: | None |
Sets the period in ms with which the CALLBACK_ACCELERATION callback is triggered periodically. A value of 0 turns the callback off.
CALLBACK_ACCELERATION is only triggered if the acceleration has changed since the last triggering.
The default value is 0.
Return type: | int |
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Returns the period as set by set_acceleration_callback_period().
Parameters: |
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Return type: | None |
Sets the thresholds for the CALLBACK_ACCELERATION_REACHED callback.
The following options are possible:
Option | Description |
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'x' | Callback is turned off |
'o' | Callback is triggered when the temperature is outside the min and max values |
'i' | Callback is triggered when the temperature is inside the min and max values |
'<' | Callback is triggered when the temperature is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the temperature is greater than the min value (max is ignored) |
The default value is ('x', 0, 0, 0, 0, 0, 0).
The following constants are available for this function:
Return type: | (chr, int, int, int, int, int, int) |
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Returns the threshold as set by set_acceleration_callback_threshold().
The following constants are available for this function:
The returned namedtuple has the variables option, min_x, max_x, min_y, max_y, min_z and max_z.
Parameters: | debounce -- int |
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Return type: | None |
Sets the period in ms with which the threshold callback
is triggered, if the threshold
keeps being reached.
The default value is 100.
Return type: | int |
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Returns the debounce period as set by set_debounce_period().
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)
accelerometer.register_callback(Accelerometer.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.
Parameters: |
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This callback is triggered periodically with the period that is set by set_acceleration_callback_period(). The parameters are the X, Y and Z acceleration.
CALLBACK_ACCELERATION is only triggered if the acceleration has changed since the last triggering.
Parameters: |
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This callback is triggered when the threshold as set by set_acceleration_callback_threshold() is reached. The parameters are the X, Y and Z acceleration.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by set_debounce_period().
This constant is used to identify a Accelerometer 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.