Ruby - LED Strip Bricklet

This is the description of the Ruby API bindings for the LED Strip Bricklet. General information and technical specifications for the LED Strip 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)

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

require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_led_strip'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your LED Strip Bricklet

ipcon = IPConnection.new # Create IP connection
ls = BrickletLEDStrip.new UID, ipcon # Create device object

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

# Set first 10 LEDs to green
ls.set_rgb_values 0, 10, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], \
                  [255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 0, 0, 0, 0, 0, 0], \
                  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

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

Callback

Download (example_callback.rb)

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

require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_led_strip'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your LED Strip Bricklet
NUM_LEDS = 16

r = [0]*NUM_LEDS
g = [0]*NUM_LEDS
b = [0]*NUM_LEDS
r_index = 0

ipcon = IPConnection.new # Create IP connection
ls = BrickletLEDStrip.new UID, ipcon # Create device object

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

# Set frame duration to 50ms (20 frames per second)
ls.set_frame_duration 50

# Use frame rendered callback to move the active LED every frame
ls.register_callback(BrickletLEDStrip::CALLBACK_FRAME_RENDERED) do |length|
  b[r_index] = 0
  if(r_index == NUM_LEDS-1)
    r_index = 0
  else
    r_index += 1
  end
  b[r_index] = 255

  # Set new data for next render cycle
  ls.set_rgb_values 0, NUM_LEDS, r, g, b
end

# Set initial rgb values to get started
ls.set_rgb_values(0, NUM_LEDS, r, g, b)

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

API

All methods listed below are thread-safe.

Basic Functions

BrickletLEDStrip::new(uid, ipcon) → led_strip
Parameters:
  • uid -- str
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

led_strip = BrickletLEDStrip.new 'YOUR_DEVICE_UID', ipcon

This object can then be used after the IP Connection is connected (see examples above).

BrickletLEDStrip#set_rgb_values(index, length, r, g, b) → nil
Parameters:
  • index -- int
  • length -- int
  • r -- [int, int, ..13x.., int]
  • g -- [int, int, ..13x.., int]
  • b -- [int, int, ..13x.., int]

Sets the RGB values for the LEDs with the given length starting from index.

To make the colors show correctly you need to configure the chip type (#set_chip_type) and a 3-channel channel mapping (#set_channel_mapping) according to the connected LEDs.

The maximum length is 16, the index goes from 0 to 319 and the rgb values have 8 bits each.

Example: If you set

  • index to 5,
  • length to 3,
  • r to [255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  • g to [0, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] and
  • b to [0, 0, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

the LED with index 5 will be red, 6 will be green and 7 will be blue.

Note

Depending on the LED circuitry colors can be permuted.

The colors will be transfered to actual LEDs when the next frame duration ends, see #set_frame_duration.

Generic approach:

  • Set the frame duration to a value that represents the number of frames per second you want to achieve.
  • Set all of the LED colors for one frame.
  • Wait for the ::CALLBACK_FRAME_RENDERED callback.
  • Set all of the LED colors for next frame.
  • Wait for the ::CALLBACK_FRAME_RENDERED callback.
  • and so on.

This approach ensures that you can change the LED colors with a fixed frame rate.

The actual number of controllable LEDs depends on the number of free Bricklet ports. See here for more information. A call of #set_rgb_values with index + length above the bounds is ignored completely.

BrickletLEDStrip#get_rgb_values(index, length) → [[int, int, ..13x.., int], [int, int, ..13x.., int], [int, int, ..13x.., int]]
Parameters:
  • index -- int
  • length -- int

Returns RGB value with the given length starting from the given index.

The values are the last values that were set by #set_rgb_values.

The returned array has the values r, g and b.

BrickletLEDStrip#set_frame_duration(duration) → nil
Parameters:duration -- int

Sets the frame duration in ms.

Example: If you want to achieve 20 frames per second, you should set the frame duration to 50ms (50ms * 20 = 1 second).

For an explanation of the general approach see #set_rgb_values.

Default value: 100ms (10 frames per second).

BrickletLEDStrip#get_frame_duration → int

Returns the frame duration in ms as set by #set_frame_duration.

BrickletLEDStrip#get_supply_voltage → int

Returns the current supply voltage of the LEDs. The voltage is given in mV.

BrickletLEDStrip#set_clock_frequency(frequency) → nil
Parameters:frequency -- int

Sets the frequency of the clock in Hz. The range is 10000Hz (10kHz) up to 2000000Hz (2MHz).

The Bricklet will choose the nearest achievable frequency, which may be off by a few Hz. You can get the exact frequency that is used by calling #get_clock_frequency.

If you have problems with flickering LEDs, they may be bits flipping. You can fix this by either making the connection between the LEDs and the Bricklet shorter or by reducing the frequency.

With a decreasing frequency your maximum frames per second will decrease too.

The default value is 1.66MHz.

Note

The frequency in firmware version 2.0.0 is fixed at 2MHz.

New in version 2.0.1 (Plugin).

BrickletLEDStrip#get_clock_frequency → int

Returns the currently used clock frequency as set by #set_clock_frequency.

New in version 2.0.1 (Plugin).

BrickletLEDStrip#set_chip_type(chip) → nil
Parameters:chip -- int

Sets the type of the LED driver chip. We currently support the chips

  • WS2801,
  • WS2811,
  • WS2812 / SK6812 / NeoPixel RGB,
  • SK6812RGBW / NeoPixel RGBW (Chip Type = WS2812),
  • LPD8806 and
  • APA102 / DotStar.

The default value is WS2801 (2801).

The following constants are available for this function:

  • BrickletLEDStrip::CHIP_TYPE_WS2801 = 2801
  • BrickletLEDStrip::CHIP_TYPE_WS2811 = 2811
  • BrickletLEDStrip::CHIP_TYPE_WS2812 = 2812
  • BrickletLEDStrip::CHIP_TYPE_LPD8806 = 8806
  • BrickletLEDStrip::CHIP_TYPE_APA102 = 102

New in version 2.0.2 (Plugin).

BrickletLEDStrip#get_chip_type → int

Returns the currently used chip type as set by #set_chip_type.

The following constants are available for this function:

  • BrickletLEDStrip::CHIP_TYPE_WS2801 = 2801
  • BrickletLEDStrip::CHIP_TYPE_WS2811 = 2811
  • BrickletLEDStrip::CHIP_TYPE_WS2812 = 2812
  • BrickletLEDStrip::CHIP_TYPE_LPD8806 = 8806
  • BrickletLEDStrip::CHIP_TYPE_APA102 = 102

New in version 2.0.2 (Plugin).

BrickletLEDStrip#set_rgbw_values(index, length, r, g, b, w) → nil
Parameters:
  • index -- int
  • length -- int
  • r -- [int, int, ..9x.., int]
  • g -- [int, int, ..9x.., int]
  • b -- [int, int, ..9x.., int]
  • w -- [int, int, ..9x.., int]

Sets the RGBW values for the LEDs with the given length starting from index.

To make the colors show correctly you need to configure the chip type (#set_chip_type) and a 4-channel channel mapping (#set_channel_mapping) according to the connected LEDs.

The maximum length is 12, the index goes from 0 to 239 and the rgbw values have 8 bits each.

Example: If you set

  • index to 5,
  • length to 4,
  • r to [255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  • g to [0, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  • b to [0, 0, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0] and
  • w to [0, 0, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0]

the LED with index 5 will be red, 6 will be green, 7 will be blue and 8 will be white.

Note

Depending on the LED circuitry colors can be permuted.

The colors will be transfered to actual LEDs when the next frame duration ends, see #set_frame_duration.

Generic approach:

  • Set the frame duration to a value that represents the number of frames per second you want to achieve.
  • Set all of the LED colors for one frame.
  • Wait for the ::CALLBACK_FRAME_RENDERED callback.
  • Set all of the LED colors for next frame.
  • Wait for the ::CALLBACK_FRAME_RENDERED callback.
  • and so on.

This approach ensures that you can change the LED colors with a fixed frame rate.

The actual number of controllable LEDs depends on the number of free Bricklet ports. See here for more information. A call of #set_rgbw_values with index + length above the bounds is ignored completely.

The LPD8806 LED driver chips have 7-bit channels for RGB. Internally the LED Strip Bricklets divides the 8-bit values set using this function by 2 to make them 7-bit. Therefore, you can just use the normal value range (0-255) for LPD8806 LEDs.

The brightness channel of the APA102 LED driver chips has 5-bit. Internally the LED Strip Bricklets divides the 8-bit values set using this function by 8 to make them 5-bit. Therefore, you can just use the normal value range (0-255) for the brightness channel of APA102 LEDs.

New in version 2.0.6 (Plugin).

BrickletLEDStrip#get_rgbw_values(index, length) → [[int, int, ..9x.., int], [int, int, ..9x.., int], [int, int, ..9x.., int], [int, int, ..9x.., int]]
Parameters:
  • index -- int
  • length -- int

Returns RGBW values with the given length starting from the given index.

The values are the last values that were set by #set_rgbw_values.

New in version 2.0.6 (Plugin).

The returned array has the values r, g, b and w.

BrickletLEDStrip#set_channel_mapping(mapping) → nil
Parameters:mapping -- int

Sets the channel mapping for the connected LEDs.

#set_rgb_values and #set_rgbw_values take the data in RGB(W) order. But the connected LED driver chips might have their 3 or 4 channels in a different order. For example, the WS2801 chips typically use BGR order, the WS2812 chips typically use GRB order and the APA102 chips typically use WBGR order.

The APA102 chips are special. They have three 8-bit channels for RGB and an additional 5-bit channel for the overall brightness of the RGB LED making them 4-channel chips. Internally the brightness channel is the first channel, therefore one of the Wxyz channel mappings should be used. Then the W channel controls the brightness.

If a 3-channel mapping is selected then #set_rgb_values has to be used. Calling #set_rgbw_values with a 3-channel mapping will produce incorrect results. Vice-versa if a 4-channel mapping is selected then #set_rgbw_values has to be used. Calling #set_rgb_values with a 4-channel mapping will produce incorrect results.

The default value is BGR (36).

The following constants are available for this function:

  • BrickletLEDStrip::CHANNEL_MAPPING_RGB = 6
  • BrickletLEDStrip::CHANNEL_MAPPING_RBG = 9
  • BrickletLEDStrip::CHANNEL_MAPPING_BRG = 33
  • BrickletLEDStrip::CHANNEL_MAPPING_BGR = 36
  • BrickletLEDStrip::CHANNEL_MAPPING_GRB = 18
  • BrickletLEDStrip::CHANNEL_MAPPING_GBR = 24
  • BrickletLEDStrip::CHANNEL_MAPPING_RGBW = 27
  • BrickletLEDStrip::CHANNEL_MAPPING_RGWB = 30
  • BrickletLEDStrip::CHANNEL_MAPPING_RBGW = 39
  • BrickletLEDStrip::CHANNEL_MAPPING_RBWG = 45
  • BrickletLEDStrip::CHANNEL_MAPPING_RWGB = 54
  • BrickletLEDStrip::CHANNEL_MAPPING_RWBG = 57
  • BrickletLEDStrip::CHANNEL_MAPPING_GRWB = 78
  • BrickletLEDStrip::CHANNEL_MAPPING_GRBW = 75
  • BrickletLEDStrip::CHANNEL_MAPPING_GBWR = 108
  • BrickletLEDStrip::CHANNEL_MAPPING_GBRW = 99
  • BrickletLEDStrip::CHANNEL_MAPPING_GWBR = 120
  • BrickletLEDStrip::CHANNEL_MAPPING_GWRB = 114
  • BrickletLEDStrip::CHANNEL_MAPPING_BRGW = 135
  • BrickletLEDStrip::CHANNEL_MAPPING_BRWG = 141
  • BrickletLEDStrip::CHANNEL_MAPPING_BGRW = 147
  • BrickletLEDStrip::CHANNEL_MAPPING_BGWR = 156
  • BrickletLEDStrip::CHANNEL_MAPPING_BWRG = 177
  • BrickletLEDStrip::CHANNEL_MAPPING_BWGR = 180
  • BrickletLEDStrip::CHANNEL_MAPPING_WRBG = 201
  • BrickletLEDStrip::CHANNEL_MAPPING_WRGB = 198
  • BrickletLEDStrip::CHANNEL_MAPPING_WGBR = 216
  • BrickletLEDStrip::CHANNEL_MAPPING_WGRB = 210
  • BrickletLEDStrip::CHANNEL_MAPPING_WBGR = 228
  • BrickletLEDStrip::CHANNEL_MAPPING_WBRG = 225

New in version 2.0.6 (Plugin).

BrickletLEDStrip#get_channel_mapping → int

Returns the currently used channel mapping as set by #set_channel_mapping.

The following constants are available for this function:

  • BrickletLEDStrip::CHANNEL_MAPPING_RGB = 6
  • BrickletLEDStrip::CHANNEL_MAPPING_RBG = 9
  • BrickletLEDStrip::CHANNEL_MAPPING_BRG = 33
  • BrickletLEDStrip::CHANNEL_MAPPING_BGR = 36
  • BrickletLEDStrip::CHANNEL_MAPPING_GRB = 18
  • BrickletLEDStrip::CHANNEL_MAPPING_GBR = 24
  • BrickletLEDStrip::CHANNEL_MAPPING_RGBW = 27
  • BrickletLEDStrip::CHANNEL_MAPPING_RGWB = 30
  • BrickletLEDStrip::CHANNEL_MAPPING_RBGW = 39
  • BrickletLEDStrip::CHANNEL_MAPPING_RBWG = 45
  • BrickletLEDStrip::CHANNEL_MAPPING_RWGB = 54
  • BrickletLEDStrip::CHANNEL_MAPPING_RWBG = 57
  • BrickletLEDStrip::CHANNEL_MAPPING_GRWB = 78
  • BrickletLEDStrip::CHANNEL_MAPPING_GRBW = 75
  • BrickletLEDStrip::CHANNEL_MAPPING_GBWR = 108
  • BrickletLEDStrip::CHANNEL_MAPPING_GBRW = 99
  • BrickletLEDStrip::CHANNEL_MAPPING_GWBR = 120
  • BrickletLEDStrip::CHANNEL_MAPPING_GWRB = 114
  • BrickletLEDStrip::CHANNEL_MAPPING_BRGW = 135
  • BrickletLEDStrip::CHANNEL_MAPPING_BRWG = 141
  • BrickletLEDStrip::CHANNEL_MAPPING_BGRW = 147
  • BrickletLEDStrip::CHANNEL_MAPPING_BGWR = 156
  • BrickletLEDStrip::CHANNEL_MAPPING_BWRG = 177
  • BrickletLEDStrip::CHANNEL_MAPPING_BWGR = 180
  • BrickletLEDStrip::CHANNEL_MAPPING_WRBG = 201
  • BrickletLEDStrip::CHANNEL_MAPPING_WRGB = 198
  • BrickletLEDStrip::CHANNEL_MAPPING_WGBR = 216
  • BrickletLEDStrip::CHANNEL_MAPPING_WGRB = 210
  • BrickletLEDStrip::CHANNEL_MAPPING_WBGR = 228
  • BrickletLEDStrip::CHANNEL_MAPPING_WBRG = 225

New in version 2.0.6 (Plugin).

Advanced Functions

BrickletLEDStrip#get_api_version → [int, int, int]

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.

BrickletLEDStrip#get_response_expected(function_id) → bool
Parameters:function_id -- int

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.

BrickletLEDStrip#set_response_expected(function_id, response_expected) → nil
Parameters:
  • function_id -- int
  • response_expected -- 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.

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:

  • BrickletLEDStrip::FUNCTION_SET_RGB_VALUES = 1
  • BrickletLEDStrip::FUNCTION_SET_FRAME_DURATION = 3
  • BrickletLEDStrip::FUNCTION_SET_CLOCK_FREQUENCY = 7
  • BrickletLEDStrip::FUNCTION_SET_CHIP_TYPE = 9
  • BrickletLEDStrip::FUNCTION_SET_RGBW_VALUES = 11
  • BrickletLEDStrip::FUNCTION_SET_CHANNEL_MAPPING = 13
  • BrickletLEDStrip::FUNCTION_ENABLE_FRAME_RENDERED_CALLBACK = 15
  • BrickletLEDStrip::FUNCTION_DISABLE_FRAME_RENDERED_CALLBACK = 16
BrickletLEDStrip#set_response_expected_all(response_expected) → nil
Parameters:response_expected -- bool

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

BrickletLEDStrip#get_identity → [str, str, str, [int, int, int], [int, int, int], int]

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.

Callback Configuration Functions

BrickletLEDStrip#register_callback(callback_id) { |param [, ...]| block } → nil
Parameters:callback_id -- int

Registers the given block with the given callback_id.

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

BrickletLEDStrip#enable_frame_rendered_callback → nil

Enables the ::CALLBACK_FRAME_RENDERED callback.

By default the callback is enabled.

New in version 2.0.6 (Plugin).

BrickletLEDStrip#disable_frame_rendered_callback → nil

Disables the ::CALLBACK_FRAME_RENDERED callback.

By default the callback is enabled.

New in version 2.0.6 (Plugin).

BrickletLEDStrip#is_frame_rendered_callback_enabled → bool

Returns true if the ::CALLBACK_FRAME_RENDERED callback is enabled, false otherwise.

New in version 2.0.6 (Plugin).

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:

led_strip.register_callback BrickletLEDStrip::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.

BrickletLEDStrip::CALLBACK_FRAME_RENDERED
Parameters:length -- int

This callback is triggered directly after a new frame is rendered. The parameter is the number of LEDs in that frame.

You should send the data for the next frame directly after this callback was triggered.

For an explanation of the general approach see #set_rgb_values.

Constants

BrickletLEDStrip::DEVICE_IDENTIFIER

This constant is used to identify a LED Strip 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.

BrickletLEDStrip::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a LED Strip Bricklet.