Shell - Multi Touch Bricklet 2.0

This is the description of the Shell 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 Shell API bindings is part of their general description.

Examples

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

Simple

Download (example-simple.sh)

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#!/bin/sh
# Connects to localhost:4223 by default, use --host and --port to change this

uid=XYZ # Change XYZ to the UID of your Multi Touch Bricklet 2.0

# Get current touch state
tinkerforge call multi-touch-v2-bricklet $uid get-touch-state

Callback

Download (example-callback.sh)

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#!/bin/sh
# Connects to localhost:4223 by default, use --host and --port to change this

uid=XYZ # Change XYZ to the UID of your Multi Touch Bricklet 2.0

# Handle incoming touch state callbacks
tinkerforge dispatch multi-touch-v2-bricklet $uid touch-state &

# Set period for touch state callback to 0.01s (10ms)
tinkerforge call multi-touch-v2-bricklet $uid set-touch-state-callback-configuration 10 true

echo "Press key to exit"; read dummy

kill -- -$$ # Stop callback dispatch in background

API

Possible exit codes for all tinkerforge commands are:

  • 1: interrupted (ctrl+c)
  • 2: syntax error
  • 21: Python 2.5 or newer is required
  • 22: Python argparse module is missing
  • 23: socket error
  • 24: other exception
  • 25: invalid placeholder in format string
  • 26: authentication error
  • 201: timeout occurred
  • 209: invalid argument value
  • 210: function is not supported
  • 211: unknown error

Command Structure

The common options of the call and dispatch commands are documented here. The specific command structure is shown below.

tinkerforge call multi-touch-v2-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The call command is used to call a function of the Multi Touch Bricklet 2.0. It can take several options:

  • --help shows help for the specific call command and exits
  • --list-functions shows a list of known functions of the Multi Touch Bricklet 2.0 and exits
tinkerforge dispatch multi-touch-v2-bricklet [<option>..] <uid> <callback>
Parameters:
  • <uid> -- string
  • <callback> -- string

The dispatch command is used to dispatch a callback of the Multi Touch Bricklet 2.0. It can take several options:

  • --help shows help for the specific dispatch command and exits
  • --list-callbacks shows a list of known callbacks of the Multi Touch Bricklet 2.0 and exits
tinkerforge call multi-touch-v2-bricklet <uid> <function> [<option>..] [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The <function> to be called can take different options depending of its kind. All functions can take the following options:

  • --help shows help for the specific function and exits

Getter functions can take the following options:

  • --execute <command> shell command line to execute for each incoming response (see section about output formatting for details)

Setter functions can take the following options:

  • --expect-response requests response and waits for it

The --expect-response option for setter functions allows to detect timeouts and other error conditions calls of setters as well. The device will then send a response for this purpose. If this option is not given for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

tinkerforge dispatch multi-touch-v2-bricklet <uid> <callback> [<option>..]
Parameters:
  • <uid> -- string
  • <callback> -- string

The <callback> to be dispatched can take several options:

  • --help shows help for the specific callback and exits
  • --execute <command> shell command line to execute for each incoming response (see section about output formatting for details)

Basic Functions

tinkerforge call multi-touch-v2-bricklet <uid> get-touch-state
Output:
  • state -- bool,bool,..10x..,bool

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 touch-state callback. You can set the callback configuration with set-touch-state-callback-configuration.

tinkerforge call multi-touch-v2-bricklet <uid> recalibrate
Output:no output

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

tinkerforge call multi-touch-v2-bricklet <uid> set-electrode-config <enabled-electrodes>
Parameters:
  • <enabled-electrodes> -- bool,bool,..10x..,bool
Output:

no output

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 touch-state callback.

Disabling electrodes will also reduce power consumption.

Default: All electrodes enabled.

tinkerforge call multi-touch-v2-bricklet <uid> get-electrode-config
Output:
  • enabled-electrodes -- bool,bool,..10x..,bool

Returns the electrode configuration, as set by set-electrode-config.

tinkerforge call multi-touch-v2-bricklet <uid> set-electrode-sensitivity <sensitivity>
Parameters:
  • <sensitivity> -- int
Output:

no output

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.

tinkerforge call multi-touch-v2-bricklet <uid> get-electrode-sensitivity
Output:
  • sensitivity -- int

Returns the current sensitivity, as set by set-electrode-sensitivity.

tinkerforge call multi-touch-v2-bricklet <uid> set-touch-led-config <config>
Parameters:
  • <config> -- int (has symbols)
Output:

no output

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 symbols are available for this function:

  • touch-led-config-off = 0, for <config>
  • touch-led-config-on = 1, for <config>
  • touch-led-config-show-heartbeat = 2, for <config>
  • touch-led-config-show-touch = 3, for <config>
tinkerforge call multi-touch-v2-bricklet <uid> get-touch-led-config
Output:
  • config -- int (has symbols)

Returns the LED configuration as set by set-touch-led-config

The following symbols are available for this function:

  • touch-led-config-off = 0, for config
  • touch-led-config-on = 1, for config
  • touch-led-config-show-heartbeat = 2, for config
  • touch-led-config-show-touch = 3, for config

Advanced Functions

tinkerforge call multi-touch-v2-bricklet <uid> get-spitfp-error-count
Output:
  • error-count-ack-checksum -- int
  • error-count-message-checksum -- int
  • error-count-frame -- int
  • error-count-overflow -- int

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.

tinkerforge call multi-touch-v2-bricklet <uid> set-bootloader-mode <mode>
Parameters:
  • <mode> -- int (has symbols)
Output:
  • status -- int (has symbols)

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 symbols are available for this function:

  • bootloader-mode-bootloader = 0, for <mode>
  • bootloader-mode-firmware = 1, for <mode>
  • bootloader-mode-bootloader-wait-for-reboot = 2, for <mode>
  • bootloader-mode-firmware-wait-for-reboot = 3, for <mode>
  • bootloader-mode-firmware-wait-for-erase-and-reboot = 4, for <mode>
  • bootloader-status-ok = 0, for status
  • bootloader-status-invalid-mode = 1, for status
  • bootloader-status-no-change = 2, for status
  • bootloader-status-entry-function-not-present = 3, for status
  • bootloader-status-device-identifier-incorrect = 4, for status
  • bootloader-status-crc-mismatch = 5, for status
tinkerforge call multi-touch-v2-bricklet <uid> get-bootloader-mode
Output:
  • mode -- int (has symbols)

Returns the current bootloader mode, see set-bootloader-mode.

The following symbols are available for this function:

  • bootloader-mode-bootloader = 0, for mode
  • bootloader-mode-firmware = 1, for mode
  • bootloader-mode-bootloader-wait-for-reboot = 2, for mode
  • bootloader-mode-firmware-wait-for-reboot = 3, for mode
  • bootloader-mode-firmware-wait-for-erase-and-reboot = 4, for mode
tinkerforge call multi-touch-v2-bricklet <uid> set-write-firmware-pointer <pointer>
Parameters:
  • <pointer> -- int
Output:

no output

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.

tinkerforge call multi-touch-v2-bricklet <uid> write-firmware <data>
Parameters:
  • <data> -- int,int,..61x..,int
Output:
  • status -- int

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.

tinkerforge call multi-touch-v2-bricklet <uid> set-status-led-config <config>
Parameters:
  • <config> -- int (has symbols)
Output:

no output

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 symbols are available for this function:

  • status-led-config-off = 0, for <config>
  • status-led-config-on = 1, for <config>
  • status-led-config-show-heartbeat = 2, for <config>
  • status-led-config-show-status = 3, for <config>
tinkerforge call multi-touch-v2-bricklet <uid> get-status-led-config
Output:
  • config -- int (has symbols)

Returns the configuration as set by set-status-led-config

The following symbols are available for this function:

  • status-led-config-off = 0, for config
  • status-led-config-on = 1, for config
  • status-led-config-show-heartbeat = 2, for config
  • status-led-config-show-status = 3, for config
tinkerforge call multi-touch-v2-bricklet <uid> get-chip-temperature
Output:
  • temperature -- int

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.

tinkerforge call multi-touch-v2-bricklet <uid> reset
Output:no output

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!

tinkerforge call multi-touch-v2-bricklet <uid> write-uid <uid>
Parameters:
  • <uid> -- int
Output:

no output

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.

tinkerforge call multi-touch-v2-bricklet <uid> read-uid
Output:
  • uid -- int

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

tinkerforge call multi-touch-v2-bricklet <uid> get-identity
Output:
  • uid -- string
  • connected-uid -- string
  • position -- char
  • hardware-version -- int,int,int
  • firmware-version -- int,int,int
  • device-identifier -- int (has symbols)

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

Callback Configuration Functions

tinkerforge call multi-touch-v2-bricklet <uid> set-touch-state-callback-configuration <period> <value-has-to-change>
Parameters:
  • <period> -- int
  • <value-has-to-change> -- bool
Output:

no output

The period in ms is the period with which the 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.

The default value is (0, false).

tinkerforge call multi-touch-v2-bricklet <uid> get-touch-state-callback-configuration
Output:
  • period -- int
  • value-has-to-change -- bool

Returns the callback configuration as set by set-touch-state-callback-configuration.

Callbacks

Callbacks can be used to receive time critical or recurring data from the device:

tinkerforge dispatch multi-touch-v2-bricklet <uid> example

The available callbacks 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.

tinkerforge dispatch multi-touch-v2-bricklet <uid> touch-state
Output:
  • state -- bool,bool,..10x..,bool

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)