This is the description of the Ruby API bindings for the Linear Poti Bricklet. General information and technical specifications for the Linear Poti 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 | #!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_linear_poti'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = '7jb' # Change to your UID
ipcon = IPConnection.new # Create IP connection
lp = BrickletLinearPoti.new UID, ipcon # Create device object
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Get current position of poti (return value has range 0-100)
position = lp.get_position
puts "Position: #{position}"
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 | #!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_linear_poti'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = '7jb' # Change to your UID
ipcon = IPConnection.new # Create IP connection
lp = BrickletLinearPoti.new UID, ipcon # Create device object
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Set Period for position callback to 0.05s (50ms)
# Note: The position position is only called every 50ms if the
# position has changed since the last call!
lp.set_position_callback_period 50
# Register position callback (parameter has range 0-100)
lp.register_callback(BrickletLinearPoti::CALLBACK_POSITION) do |position|
puts "Position: #{position}"
end
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:
linear_poti = BrickletLinearPoti.new 'YOUR_DEVICE_UID', ipcon
This object can then be used after the IP Connection is connected (see examples above).
Returns the position of the Linear Potentiometer. The value is between 0 (slider down) and 100 (slider up).
If you want to get the position periodically, it is recommended to use the callback ::CALLBACK_POSITION and set the period with #set_position_callback_period.
Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.
Note
The value returned by #get_position is averaged over several samples to yield less noise, while #get_analog_value gives back raw unfiltered analog values. The only reason to use #get_analog_value is, if you need the full resolution of the analog-to-digital converter.
If you want the analog value periodically, it is recommended to use the callback ::CALLBACK_ANALOG_VALUE and set the period with #set_analog_value_callback_period.
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_POSITION callback is triggered periodically. A value of 0 turns the callback off.
::CALLBACK_POSITION is only triggered if the position has changed since the last triggering.
The default value is 0.
Returns the period as set by #set_position_callback_period.
Parameters: | period -- int |
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Sets the period in ms with which the ::CALLBACK_ANALOG_VALUE callback is triggered periodically. A value of 0 turns the callback off.
::CALLBACK_ANALOG_VALUE is only triggered if the analog value has changed since the last triggering.
The default value is 0.
Returns the period as set by #set_analog_value_callback_period.
Parameters: |
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Sets the thresholds for the ::CALLBACK_POSITION_REACHED callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the position is outside the min and max values |
'i' | Callback is triggered when the position is inside the min and max values |
'<' | Callback is triggered when the position is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the position 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_position_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_ANALOG_VALUE_REACHED callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the analog value is outside the min and max values |
'i' | Callback is triggered when the analog value is inside the min and max values |
'<' | Callback is triggered when the analog value is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the analog 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_analog_value_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:
linear_poti.register_callback BrickletLinearPoti::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: | position -- int |
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This callback is triggered periodically with the period that is set by #set_position_callback_period. The parameter is the position of the Linear Potentiometer.
::CALLBACK_POSITION is only triggered if the position has changed since the last triggering.
Parameters: | value -- int |
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This callback is triggered periodically with the period that is set by #set_analog_value_callback_period. The parameter is the analog value of the Linear Potentiometer.
::CALLBACK_ANALOG_VALUE is only triggered if the position has changed since the last triggering.
Parameters: | position -- int |
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This callback is triggered when the threshold as set by #set_position_callback_threshold is reached. The parameter is the position of the Linear Potentiometer.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by #set_debounce_period.
Parameters: | value -- int |
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This callback is triggered when the threshold as set by #set_analog_value_callback_threshold is reached. The parameter is the analog value of the Linear Potentiometer.
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 Linear Poti 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.