Software / API Bindings / Ruby / API Reference and Examples / Bricklets / Linear Poti Bricklet

Ruby - Linear Poti Bricklet¶

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.

Examples¶

The example code below is Public Domain (CC0 1.0).

Simple¶

Download (example_simple.rb)

#!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-

require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_linear_poti'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your Linear Poti Bricklet

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
position = lp.get_position
puts "Position: #{position} %" # Range: 0 to 100

puts 'Press key to exit'
$stdin.gets
ipcon.disconnect

Callback¶

Download (example_callback.rb)

#!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-

require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_linear_poti'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your Linear Poti Bricklet

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

# Register position callback
lp.register_callback(BrickletLinearPoti::CALLBACK_POSITION) do |position|
  puts "Position: #{position} %" # Range: 0 to 100
end

# Set period for position callback to 0.05s (50ms)
# Note: The position callback is only called every 0.05 seconds
#       if the position has changed since the last call!
lp.set_position_callback_period 50

puts 'Press key to exit'
$stdin.gets
ipcon.disconnect

API¶

All functions listed below are thread-safe.

Basic Functions¶

BrickletLinearPoti::new(uid, ipcon) → linear_poti¶

Parameters:	uid – Type: str ipcon – Type: IPConnection
Returns:	linear_poti – Type: BrickletLinearPoti

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.

BrickletLinearPoti#get_position → int¶

Returns:	position – Type: int, Unit: 1 %, Range: [0 to 100]

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_POSITION callback and set the period with #set_position_callback_period.

Advanced Functions¶

BrickletLinearPoti#get_analog_value → int¶

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

Returns the value as read by a 12-bit analog-to-digital converter.

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_ANALOG_VALUE callback and set the period with #set_analog_value_callback_period.

BrickletLinearPoti#get_identity → [str, str, chr, [int, ...], [int, ...], int]¶

Return Array:

Return Array:	0: uid – Type: str, Length: up to 8 1: connected_uid – Type: str, Length: up to 8 2: position – Type: chr, Range: ['a' to 'h', 'z'] 3: 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] 4: 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] 5: device_identifier – Type: int, Range: [0 to 2¹⁶ - 1]

0: uid – Type: str, Length: up to 8
1: connected_uid – Type: str, Length: up to 8
2: position – Type: chr, Range: ['a' to 'h', 'z']
3: 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]

4: 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]

5: 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¶

BrickletLinearPoti#register_callback(callback_id) { |param [, ...]| block } → nil¶

Parameters:	callback_id – Type: int

Registers the given block with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletLinearPoti#set_position_callback_period(period) → nil¶

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

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

The ::CALLBACK_POSITION callback is only triggered if the position has changed since the last triggering.

BrickletLinearPoti#get_position_callback_period → int¶

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

Returns the period as set by #set_position_callback_period.

BrickletLinearPoti#set_analog_value_callback_period(period) → nil¶

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

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

The ::CALLBACK_ANALOG_VALUE callback is only triggered if the analog value has changed since the last triggering.

BrickletLinearPoti#get_analog_value_callback_period → int¶

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

Returns the period as set by #set_analog_value_callback_period.

BrickletLinearPoti#set_position_callback_threshold(option, min, max) → nil¶

Parameters:	option – Type: chr, Range: See constants, Default: 'x' min – Type: int, Unit: 1 %, Range: [0 to 2¹⁶ - 1], Default: 0 max – Type: int, Unit: 1 %, Range: [0 to 2¹⁶ - 1], Default: 0

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 following constants are available for this function:

For option:

BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'

BrickletLinearPoti#get_position_callback_threshold → [chr, int, int]¶

Return Array:	0: option – Type: chr, Range: See constants, Default: 'x' 1: min – Type: int, Unit: 1 %, Range: [0 to 2¹⁶ - 1], Default: 0 2: max – Type: int, Unit: 1 %, Range: [0 to 2¹⁶ - 1], Default: 0

Returns the threshold as set by #set_position_callback_threshold.

The following constants are available for this function:

For option:

BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'

BrickletLinearPoti#set_analog_value_callback_threshold(option, min, max) → nil¶

Parameters:	option – Type: chr, Range: See constants, Default: 'x' min – Type: int, Range: [0 to 2¹⁶ - 1], Default: 0 max – Type: int, Range: [0 to 2¹⁶ - 1], Default: 0

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 following constants are available for this function:

For option:

BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'

BrickletLinearPoti#get_analog_value_callback_threshold → [chr, int, int]¶

Return Array:	0: option – Type: chr, Range: See constants, Default: 'x' 1: min – Type: int, Range: [0 to 2¹⁶ - 1], Default: 0 2: max – Type: int, Range: [0 to 2¹⁶ - 1], Default: 0

Returns the threshold as set by #set_analog_value_callback_threshold.

The following constants are available for this function:

For option:

BrickletLinearPoti::THRESHOLD_OPTION_OFF = 'x'
BrickletLinearPoti::THRESHOLD_OPTION_OUTSIDE = 'o'
BrickletLinearPoti::THRESHOLD_OPTION_INSIDE = 'i'
BrickletLinearPoti::THRESHOLD_OPTION_SMALLER = '<'
BrickletLinearPoti::THRESHOLD_OPTION_GREATER = '>'

BrickletLinearPoti#set_debounce_period(debounce) → nil¶

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

Sets the period with which the threshold callbacks

::CALLBACK_POSITION_REACHED,
::CALLBACK_ANALOG_VALUE_REACHED

are triggered, if the thresholds

#set_position_callback_threshold,
#set_analog_value_callback_threshold

keep being reached.

BrickletLinearPoti#get_debounce_period → int¶

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 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.

BrickletLinearPoti::CALLBACK_POSITION¶

Callback Parameters:	position – Type: int, Unit: 1 %, Range: [0 to 100]

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.

The ::CALLBACK_POSITION callback is only triggered if the position has changed since the last triggering.

BrickletLinearPoti::CALLBACK_ANALOG_VALUE¶

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

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.

The ::CALLBACK_ANALOG_VALUE callback is only triggered if the position has changed since the last triggering.

BrickletLinearPoti::CALLBACK_POSITION_REACHED¶

Callback Parameters:	position – Type: int, Unit: 1 %, Range: [0 to 100]

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.

BrickletLinearPoti::CALLBACK_ANALOG_VALUE_REACHED¶

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

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.

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.

BrickletLinearPoti#get_api_version → [int, ...]¶

Return Array:	0: 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.

BrickletLinearPoti#get_response_expected(function_id) → bool¶

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:

BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_PERIOD = 3
BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 7
BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
BrickletLinearPoti::FUNCTION_SET_DEBOUNCE_PERIOD = 11

BrickletLinearPoti#set_response_expected(function_id, response_expected) → nil¶

Parameters:	function_id – Type: int, Range: See constants response_expected – Type: bool

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.

The following constants are available for this function:

For function_id:

BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_PERIOD = 3
BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 5
BrickletLinearPoti::FUNCTION_SET_POSITION_CALLBACK_THRESHOLD = 7
BrickletLinearPoti::FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 9
BrickletLinearPoti::FUNCTION_SET_DEBOUNCE_PERIOD = 11

BrickletLinearPoti#set_response_expected_all(response_expected) → nil¶

Parameters:	response_expected – Type: bool

Changes the response expected flag for all setter and callback configuration functions of this device at once.

Constants¶

BrickletLinearPoti::DEVICE_IDENTIFIER¶

This constant is used to identify a Linear Poti 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.

BrickletLinearPoti::DEVICE_DISPLAY_NAME¶: This constant represents the human readable name of a Linear Poti Bricklet.