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 Ruby API bindings for the Laser Range Finder Bricklet. General information and technical specifications for the Laser Range Finder Bricklet are summarized in its hardware description.
An installation guide for the Ruby 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 29 | #!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_laser_range_finder'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change to your UID
ipcon = IPConnection.new # Create IP connection
lrf = BrickletLaserRangeFinder.new UID, ipcon # Create device object
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Turn laser on and wait 250ms for very first measurement to be ready
lrf.enable_laser
sleep 0.25
# Get current distance (unit is cm)
distance = lrf.get_distance
puts "Distance: #{distance} cm"
puts 'Press key to exit'
$stdin.gets
ipcon.disconnect
|
Download (example_callback.rb)
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 ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_laser_range_finder'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change to your UID
ipcon = IPConnection.new # Create IP connection
lrf = BrickletLaserRangeFinder.new UID, ipcon # Create device object
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Turn laser on and wait 250ms for very first measurement to be ready
lrf.enable_laser
sleep 0.25
# Set Period for distance callback to 1s (1000ms)
# Note: The distance callback is only called every second if the
# distance has changed since the last call!
lrf.set_distance_callback_period 1000
# Register distance callback (parameter has unit cm)
lrf.register_callback(BrickletLaserRangeFinder::CALLBACK_DISTANCE) do |distance|
puts "Distance: #{distance} cm"
end
puts 'Press key to exit'
$stdin.gets
ipcon.disconnect
|
Download (example_threshold.rb)
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 36 | #!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_laser_range_finder'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change to your UID
ipcon = IPConnection.new # Create IP connection
lrf = BrickletLaserRangeFinder.new UID, ipcon # Create device object
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Turn laser on and wait 250ms for very first measurement to be ready
lrf.enable_laser
sleep 0.25
# Get threshold callbacks with a debounce time of 10 seconds (10000ms)
lrf.set_debounce_period 10000
# Register threshold reached callback for distance greater than 20 cm
lrf.register_callback(BrickletLaserRangeFinder::CALLBACK_DISTANCE_REACHED) do |distance|
puts "Distance: #{distance} cm."
end
# Configure threshold for greater than 20 cm
lrf.set_distance_callback_threshold '>', 20, 0
puts 'Press key to exit'
$stdin.gets
ipcon.disconnect
|
All methods listed below are thread-safe.
Parameters: |
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Creates an object with the unique device ID uid:
laser_range_finder = BrickletLaserRangeFinder.new 'YOUR_DEVICE_UID', ipcon
This object can then be used after the IP Connection is connected (see examples above).
Returns the measured distance. The value has a range of 0 to 4000 and is given in cm.
The Laser Range Finder Bricklet knows different modes. Distances are only measured in the distance measurement mode, see #set_mode. Also the laser has to be enabled, see #enable_laser.
If you want to get the distance periodically, it is recommended to use the callback ::CALLBACK_DISTANCE and set the period with #set_distance_callback_period.
Returns the measured velocity. The value has a range of 0 to 12700 and is given in 1/100 m/s.
The Laser Range Finder Bricklet knows different modes. Velocity is only measured in the velocity measurement modes, see #set_mode. Also the laser has to be enabled, see #enable_laser.
If you want to get the velocity periodically, it is recommended to use the callback ::CALLBACK_VELOCITY and set the period with #set_velocity_callback_period.
Parameters: | mode -- int |
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The LIDAR has five different modes. One mode is for distance measurements and four modes are for velocity measurements with different ranges.
The following modes are available:
The default mode is 0 (distance is measured).
The following constants are available for this function:
Returns the mode as set by #set_mode.
The following constants are available for this function:
Activates the laser of the LIDAR.
We recommend that you wait 250ms after enabling the laser before the first call of #get_distance to ensure stable measurements.
Deactivates the laser of the LIDAR.
Returns true if the laser is enabled, false otherwise.
Parameters: |
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Sets the length of a moving averaging for the distance and velocity.
Setting the length to 0 will turn the averaging completely off. With less averaging, there is more noise on the data.
The range for the averaging is 0-30.
The default value is 10.
Returns the length moving average as set by #set_moving_average.
The returned array has the values distance_average_length and velocity_average_length.
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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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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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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Changes the response expected flag for all setter and callback configuration functions of this device at once.
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 array has the values uid, connected_uid, position, hardware_version, firmware_version and device_identifier.
Parameters: | id -- int |
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Registers a callback with ID id to the given block. The available IDs with corresponding function signatures are listed below.
Parameters: | period -- int |
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Sets the period in ms with which the ::CALLBACK_DISTANCE callback is triggered periodically. A value of 0 turns the callback off.
::CALLBACK_DISTANCE is only triggered if the distance value has changed since the last triggering.
The default value is 0.
Returns the period as set by #set_distance_callback_period.
Parameters: | period -- int |
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Sets the period in ms with which the ::CALLBACK_VELOCITY callback is triggered periodically. A value of 0 turns the callback off.
::CALLBACK_VELOCITY is only triggered if the velocity value has changed since the last triggering.
The default value is 0.
Returns the period as set by #set_velocity_callback_period.
Parameters: |
|
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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 default value is ('x', 0, 0).
The following constants are available for this function:
Returns the threshold as set by #set_distance_callback_threshold.
The following constants are available for this function:
The returned array has the values option, min and max.
Parameters: |
|
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Sets the thresholds for the ::CALLBACK_VELOCITY_REACHED callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the velocity is outside the min and max values |
'i' | Callback is triggered when the velocity is inside the min and max values |
'<' | Callback is triggered when the velocity is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the velocity is greater than the min value (max is ignored) |
The default value is ('x', 0, 0).
The following constants are available for this function:
Returns the threshold as set by #set_velocity_callback_threshold.
The following constants are available for this function:
The returned array has the values option, min and max.
Parameters: | debounce -- int |
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Sets the period in ms with which the threshold callbacks
are triggered, if the thresholds
keep being reached.
The default value is 100.
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 is a block:
laser_range_finder.register_callback BrickletLaserRangeFinder::CALLBACK_EXAMPLE, do |param|
puts "#{param}"
end
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: | distance -- int |
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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.
::CALLBACK_DISTANCE is only triggered if the distance value has changed since the last triggering.
Parameters: | velocity -- int |
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This callback is triggered periodically with the period that is set by #set_velocity_callback_period. The parameter is the velocity value of the sensor.
::CALLBACK_VELOCITY is only triggered if the velocity has changed since the last triggering.
Parameters: | distance -- int |
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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.
Parameters: | velocity -- int |
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This callback is triggered when the threshold as set by #set_velocity_callback_threshold is reached. The parameter is the velocity value of the sensor.
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 Laser Range Finder 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.