MQTT - Multi Touch Bricklet¶

Callback¶

Download (example-callback.txt)

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# Change XYZ to the UID of your Multi Touch Bricklet

setup:
    # Handle incoming touch state callbacks
    subscribe to tinkerforge/callback/multi_touch_bricklet/XYZ/touch_state
        if a message arrives:
            # message contains state as int
            set result_string to ""
            if bit 12 of state is set
                append "In proximity, " to result_string
            endif

            if bits 0 to 11 of state are not set
                append "No electrodes touched" to result_string
            elseif
                append "Electrodes " to result_string
                for i in 0..12
                    if bit i of state is set
                        append i and " " to result_string
                    endif
                endfor
            endif

            print result_string
        endif
    endsubscribe

    publish '{"register": true}' to tinkerforge/register/multi_touch_bricklet/XYZ/touch_state # Register touch_state callback

Simple¶

Download (example-simple.txt)

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# Change XYZ to the UID of your Multi Touch Bricklet

setup:
    # Get current touch state
    subscribe to tinkerforge/response/multi_touch_bricklet/XYZ/get_touch_state
        if a message arrives:
            # message contains state as int
            set result_string to ""
            if bit 12 of state is set
                append "In proximity, " to result_string
            endif

            if bits 0 to 11 of state are not set
                append "No electrodes touched" to result_string
            elseif
                append "Electrodes " to result_string
                for i in 0..12
                    if bit i of state is set
                        append i and " " to result_string
                    endif
                endfor
            endif

            print result_string
        endif
    endsubscribe

    publish '' to tinkerforge/request/multi_touch_bricklet/XYZ/get_touch_state

Basic Functions¶

request/multi_touch_bricklet/<UID>/get_touch_state¶

Request:	empty payload
Response:	state – Type: int, Range: [0 to 213 - 1]

Returns the current touch state. The state is given as a bitfield.

Bits 0 to 11 represent the 12 electrodes and bit 12 represents the proximity.

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

Example: The state 4103 = 0x1007 = 0b1000000000111 means that electrodes 0, 1 and 2 are touched and that something is in the proximity of the electrodes.

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.

request/multi_touch_bricklet/<UID>/recalibrate¶

Request:	empty payload
Response:	no response

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

request/multi_touch_bricklet/<UID>/set_electrode_config¶

Request:	enabled_electrodes – Type: int, Range: [0 to 213 - 1], Default: 213 - 1
Response:	no response

Enables/disables electrodes with a bitfield (see request/multi_touch_bricklet/<UID>/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 bit (bit 12) if the proximity feature is not needed. This will reduce the amount of traffic that is produced by the register/multi_touch_bricklet/<UID>/touch_state callback.

Disabling electrodes will also reduce power consumption.

Default: 8191 = 0x1FFF = 0b1111111111111 (all electrodes and proximity feature enabled)

request/multi_touch_bricklet/<UID>/get_electrode_config¶

Request:	empty payload
Response:	enabled_electrodes – Type: int, Range: [0 to 213 - 1], Default: 213 - 1

Returns the electrode configuration, as set by request/multi_touch_bricklet/<UID>/set_electrode_config.

request/multi_touch_bricklet/<UID>/set_electrode_sensitivity¶

Request:	sensitivity – Type: int, Range: [5 to 201], Default: 181
Response:	no response

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 request/multi_touch_bricklet/<UID>/recalibrate to calibrate the electrodes with the newly defined sensitivity.

request/multi_touch_bricklet/<UID>/get_electrode_sensitivity¶

Request:	empty payload
Response:	sensitivity – Type: int, Range: [5 to 201], Default: 181

Returns the current sensitivity, as set by request/multi_touch_bricklet/<UID>/set_electrode_sensitivity.

Advanced Functions¶

request/multi_touch_bricklet/<UID>/get_identity¶

Request:

empty payload

Response:

uid – Type: string, Length: up to 8 connected_uid – Type: string, Length: up to 8 position – Type: char, Range: ["a" to "h", "z"] 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] 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] device_identifier – Type: int, Range: [0 to 216 - 1] _display_name – Type: string

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. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.

The display name contains the Multi Touch's name in a human readable form.

Callbacks¶

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the corresponding .../register/... topic and an optional suffix. This suffix can be used to deregister the callback later.

register/multi_touch_bricklet/<UID>/touch_state¶

Register Request:	register – Type: bool
Callback Response:	state – Type: int, Range: [0 to 213 - 1]

A callback can be registered for this event by publishing to the .../register/multi_touch_bricklet/<UID>/touch_state[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/multi_touch_bricklet/<UID>/touch_state[/<SUFFIX>] topic for each registered suffix.

Returns the current touch state, see request/multi_touch_bricklet/<UID>/get_touch_state for information about the state.

This callback is triggered every time the touch state changes.