Ruby - Multi Touch Bricklet 2.0

This is the description of the Ruby API bindings for the Multi Touch Bricklet 2.0. General information and technical specifications for the Multi Touch Bricklet 2.0 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_multi_touch_v2'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your Multi Touch Bricklet 2.0

ipcon = IPConnection.new # Create IP connection
mt = BrickletMultiTouchV2.new UID, ipcon # Create device object

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

# Get current touch state
state = mt.get_touch_state

puts "Electrode 0: #{state[0]}"
puts "Electrode 1: #{state[1]}"
puts "Electrode 2: #{state[2]}"
puts "Electrode 3: #{state[3]}"
puts "Electrode 4: #{state[4]}"
puts "Electrode 5: #{state[5]}"
puts "Electrode 6: #{state[6]}"
puts "Electrode 7: #{state[7]}"
puts "Electrode 8: #{state[8]}"
puts "Electrode 9: #{state[9]}"
puts "Electrode 10: #{state[10]}"
puts "Electrode 11: #{state[11]}"
puts "Proximity: #{state[12]}"

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_multi_touch_v2'

include Tinkerforge

HOST = 'localhost'
PORT = 4223
UID = 'XYZ' # Change XYZ to the UID of your Multi Touch Bricklet 2.0

ipcon = IPConnection.new # Create IP connection
mt = BrickletMultiTouchV2.new UID, ipcon # Create device object

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

# Register touch state callback
mt.register_callback(BrickletMultiTouchV2::CALLBACK_TOUCH_STATE) do |state|
  puts "Electrode 0: #{state[0]}"
  puts "Electrode 1: #{state[1]}"
  puts "Electrode 2: #{state[2]}"
  puts "Electrode 3: #{state[3]}"
  puts "Electrode 4: #{state[4]}"
  puts "Electrode 5: #{state[5]}"
  puts "Electrode 6: #{state[6]}"
  puts "Electrode 7: #{state[7]}"
  puts "Electrode 8: #{state[8]}"
  puts "Electrode 9: #{state[9]}"
  puts "Electrode 10: #{state[10]}"
  puts "Electrode 11: #{state[11]}"
  puts "Proximity: #{state[12]}"
  puts ''
end

# Set period for touch state callback to 0.01s (10ms)
mt.set_touch_state_callback_configuration 10, true

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

API

All methods listed below are thread-safe.

Basic Functions

BrickletMultiTouchV2::new(uid, ipcon) → multi_touch_v2
Parameters:
  • uid – Type: str
  • ipcon – Type: IPConnection
Returns:
  • multi_touch_v2 – Type: BrickletMultiTouchV2

Creates an object with the unique device ID uid:

multi_touch_v2 = BrickletMultiTouchV2.new 'YOUR_DEVICE_UID', ipcon

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

BrickletMultiTouchV2#get_touch_state → [bool, ...]
Returns:
  • state – Type: [bool, ...], Length: 13

Returns the current touch state. The state is given as a array of bools.

Element 0 to 11 represent the 12 electrodes and element 12 represents the proximity.

If an electrode is touched, the corresponding element is true. If a hand or similar is in proximity to the electrodes, element 12 is true.

The proximity is activated with a distance of 1-2cm. An electrode is already counted as touched if a finger is nearly touching the electrode. This means that you can put a piece of paper or foil or similar on top of a electrode to build a touch panel with a professional look.

If you want to get the value periodically, it is recommended to use the ::CALLBACK_TOUCH_STATE callback. You can set the callback configuration with #set_touch_state_callback_configuration.

BrickletMultiTouchV2#recalibrate → nil

Recalibrates the electrodes. Call this function whenever you changed or moved you electrodes.

BrickletMultiTouchV2#set_electrode_config(enabled_electrodes) → nil
Parameters:
  • enabled_electrodes – Type: [bool, ...], Length: 13

Enables/disables electrodes with a bool array (see #get_touch_state).

True enables the electrode, false disables the electrode. A disabled electrode will always return false as its state. If you don't need all electrodes you can disable the electrodes that are not needed.

It is recommended that you disable the proximity electrode (element 12) if the proximity feature is not needed. This will reduce the amount of traffic that is produced by the ::CALLBACK_TOUCH_STATE callback.

Disabling electrodes will also reduce power consumption.

Default: All electrodes enabled.

BrickletMultiTouchV2#get_electrode_config → [bool, ...]
Returns:
  • enabled_electrodes – Type: [bool, ...], Length: 13

Returns the electrode configuration, as set by #set_electrode_config.

BrickletMultiTouchV2#set_electrode_sensitivity(sensitivity) → nil
Parameters:
  • sensitivity – Type: int, Range: [0 to 255]

Sets the sensitivity of the electrodes. An electrode with a high sensitivity will register a touch earlier then an electrode with a low sensitivity.

If you build a big electrode you might need to decrease the sensitivity, since the area that can be charged will get bigger. If you want to be able to activate an electrode from further away you need to increase the sensitivity.

After a new sensitivity is set, you likely want to call #recalibrate to calibrate the electrodes with the newly defined sensitivity.

The valid sensitivity value range is 5-201.

The default sensitivity value is 181.

BrickletMultiTouchV2#get_electrode_sensitivity → int
Returns:
  • sensitivity – Type: int, Range: [0 to 255]

Returns the current sensitivity, as set by #set_electrode_sensitivity.

BrickletMultiTouchV2#set_touch_led_config(config) → nil
Parameters:
  • config – Type: int, Range: See constants

Configures the touch LED to be either turned off, turned on, blink in heartbeat mode or show the touch state (electrode touched = LED on).

The default value is 3 (show touch state).

The following constants are available for this function:

For config:

  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_SHOW_TOUCH = 3
BrickletMultiTouchV2#get_touch_led_config → int
Returns:
  • config – Type: int, Range: See constants

Returns the LED configuration as set by #set_touch_led_config

The following constants are available for this function:

For config:

  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2::TOUCH_LED_CONFIG_SHOW_TOUCH = 3

Advanced Functions

BrickletMultiTouchV2#get_api_version → [int, ...]
Returns:
  • api_version – Type: [int, ...], Length: 3, Range: [0 to 255]

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.

BrickletMultiTouchV2#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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletMultiTouchV2::FUNCTION_SET_TOUCH_STATE_CALLBACK_CONFIGURATION = 2
  • BrickletMultiTouchV2::FUNCTION_RECALIBRATE = 5
  • BrickletMultiTouchV2::FUNCTION_SET_ELECTRODE_CONFIG = 6
  • BrickletMultiTouchV2::FUNCTION_SET_ELECTRODE_SENSITIVITY = 8
  • BrickletMultiTouchV2::FUNCTION_SET_TOUCH_LED_CONFIG = 10
  • BrickletMultiTouchV2::FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletMultiTouchV2::FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletMultiTouchV2::FUNCTION_RESET = 243
  • BrickletMultiTouchV2::FUNCTION_WRITE_UID = 248
BrickletMultiTouchV2#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.

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 constants are available for this function:

For function_id:

  • BrickletMultiTouchV2::FUNCTION_SET_TOUCH_STATE_CALLBACK_CONFIGURATION = 2
  • BrickletMultiTouchV2::FUNCTION_RECALIBRATE = 5
  • BrickletMultiTouchV2::FUNCTION_SET_ELECTRODE_CONFIG = 6
  • BrickletMultiTouchV2::FUNCTION_SET_ELECTRODE_SENSITIVITY = 8
  • BrickletMultiTouchV2::FUNCTION_SET_TOUCH_LED_CONFIG = 10
  • BrickletMultiTouchV2::FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletMultiTouchV2::FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletMultiTouchV2::FUNCTION_RESET = 243
  • BrickletMultiTouchV2::FUNCTION_WRITE_UID = 248
BrickletMultiTouchV2#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.

BrickletMultiTouchV2#get_spitfp_error_count → [int, int, int, int]
Return Array:
  • 0: error_count_ack_checksum – Type: int, Range: [0 to 232 - 1]
  • 1: error_count_message_checksum – Type: int, Range: [0 to 232 - 1]
  • 2: error_count_frame – Type: int, Range: [0 to 232 - 1]
  • 3: error_count_overflow – Type: int, Range: [0 to 232 - 1]

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

BrickletMultiTouchV2#set_bootloader_mode(mode) → int
Parameters:
  • mode – Type: int, Range: See constants
Returns:
  • status – Type: int, Range: See constants

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

For mode:

  • BrickletMultiTouchV2::BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletMultiTouchV2::BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletMultiTouchV2::BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletMultiTouchV2::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletMultiTouchV2::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For status:

  • BrickletMultiTouchV2::BOOTLOADER_STATUS_OK = 0
  • BrickletMultiTouchV2::BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletMultiTouchV2::BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletMultiTouchV2::BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletMultiTouchV2::BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletMultiTouchV2::BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletMultiTouchV2#get_bootloader_mode → int
Returns:
  • mode – Type: int, Range: See constants

Returns the current bootloader mode, see #set_bootloader_mode.

The following constants are available for this function:

For mode:

  • BrickletMultiTouchV2::BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletMultiTouchV2::BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletMultiTouchV2::BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletMultiTouchV2::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletMultiTouchV2::BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
BrickletMultiTouchV2#set_write_firmware_pointer(pointer) → nil
Parameters:
  • pointer – Type: int, Range: [0 to 232 - 1]

Sets the firmware pointer for #write_firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletMultiTouchV2#write_firmware(data) → int
Parameters:
  • data – Type: [int, ...], Length: 64, Range: [0 to 255]
Returns:
  • status – Type: int, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by #set_write_firmware_pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletMultiTouchV2#set_status_led_config(config) → nil
Parameters:
  • config – Type: int, Range: See constants

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

For config:

  • BrickletMultiTouchV2::STATUS_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2::STATUS_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2::STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2::STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletMultiTouchV2#get_status_led_config → int
Returns:
  • config – Type: int, Range: See constants

Returns the configuration as set by #set_status_led_config

The following constants are available for this function:

For config:

  • BrickletMultiTouchV2::STATUS_LED_CONFIG_OFF = 0
  • BrickletMultiTouchV2::STATUS_LED_CONFIG_ON = 1
  • BrickletMultiTouchV2::STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletMultiTouchV2::STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletMultiTouchV2#get_chip_temperature → int
Returns:
  • temperature – Type: int, Range: [-215 to 215 - 1]

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

BrickletMultiTouchV2#reset → nil

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

BrickletMultiTouchV2#write_uid(uid) → nil
Parameters:
  • uid – Type: int, Range: [0 to 232 - 1]

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

BrickletMultiTouchV2#read_uid → int
Returns:
  • uid – Type: int, Range: [0 to 232 - 1]

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

BrickletMultiTouchV2#get_identity → [str, str, chr, [int, ...], [int, ...], int]
Return Array:
  • 0: uid – Type: str, Length: up to 8
  • 1: connected_uid – Type: str, Length: up to 8
  • 2: position – Type: chr
  • 3: hardware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • 4: firmware_version – Type: [int, ...], Length: 3, 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' or 'd'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

BrickletMultiTouchV2#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.

BrickletMultiTouchV2#set_touch_state_callback_configuration(period, value_has_to_change) → nil
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

BrickletMultiTouchV2#get_touch_state_callback_configuration → [int, bool]
Return Array:
  • 0: period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • 1: value_has_to_change – Type: bool, Default: false

Returns the callback configuration as set by #set_touch_state_callback_configuration.

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:

multi_touch_v2.register_callback BrickletMultiTouchV2::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.

BrickletMultiTouchV2::CALLBACK_TOUCH_STATE
Callback Parameters:
  • state – Type: [bool, ...], Length: 13

Returns the current touch state, see #get_touch_state for information about the state.

This callback is triggered every time the touch state changes with a given period (see #set_touch_state_callback_configuration)

Constants

BrickletMultiTouchV2::DEVICE_IDENTIFIER

This constant is used to identify a Multi Touch Bricklet 2.0.

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.

BrickletMultiTouchV2::DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Multi Touch Bricklet 2.0.