MQTT - Hall Effect Bricklet¶

Simple¶

Download (example-simple.txt)

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# Change XYZ to the UID of your Hall Effect Bricklet

setup:
    # Get current edge count without reset
    subscribe to tinkerforge/response/hall_effect_bricklet/XYZ/get_edge_count
    publish '{"reset_counter": false}' to tinkerforge/request/hall_effect_bricklet/XYZ/get_edge_count

Callback¶

Download (example-callback.txt)

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# Change XYZ to the UID of your Hall Effect Bricklet

setup:
    # Handle incoming edge count callbacks
    subscribe to tinkerforge/callback/hall_effect_bricklet/XYZ/edge_count
    publish '{"register": true}' to tinkerforge/register/hall_effect_bricklet/XYZ/edge_count # Register edge_count callback

    # Set period for edge count callback to 0.05s (50ms)
    # Note: The edge count callback is only called every 0.05 seconds
    #       if the edge count has changed since the last call!
    publish '{"period": 50}' to tinkerforge/request/hall_effect_bricklet/XYZ/set_edge_count_callback_period

Basic Functions¶

request/hall_effect_bricklet/<UID>/get_value¶

Request:	empty payload
Response:	value – Type: bool

Returns true if a magnetic field of 3.5 millitesla or greater is detected.

request/hall_effect_bricklet/<UID>/get_edge_count¶

Request:	reset_counter – Type: bool
Response:	count – Type: int, Range: [0 to 232 - 1]

Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with request/hall_effect_bricklet/<UID>/set_edge_count_config.

If you set the reset counter to true, the count is set back to 0 directly after it is read.

Advanced Functions¶

request/hall_effect_bricklet/<UID>/set_edge_count_config¶

Request:	edge_type – Type: int, Range: See symbols, Default: 0 debounce – Type: int, Unit: 1 ms, Range: [0 to 255], Default: 100
Response:	no response

The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:

• 0 = rising
• 1 = falling
• 2 = both

A magnetic field of 3.5 millitesla or greater causes a falling edge and a magnetic field of 2.5 millitesla or smaller causes a rising edge.

If a magnet comes near the Bricklet the signal goes low (falling edge), if a magnet is removed from the vicinity the signal goes high (rising edge).

Configuring an edge counter resets its value to 0.

If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

The following symbols are available for this function:

For edge_type:

• "rising" = 0
• "falling" = 1
• "both" = 2

request/hall_effect_bricklet/<UID>/get_edge_count_config¶

Request:	empty payload
Response:	edge_type – Type: int, Range: See symbols, Default: 0 debounce – Type: int, Unit: 1 ms, Range: [0 to 255], Default: 100

Returns the edge type and debounce time as set by request/hall_effect_bricklet/<UID>/set_edge_count_config.

The following symbols are available for this function:

For edge_type:

• "rising" = 0
• "falling" = 1
• "both" = 2

request/hall_effect_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 Hall Effect's name in a human readable form.

Callback Configuration Functions¶

request/hall_effect_bricklet/<UID>/set_edge_interrupt¶

Request:	edges – Type: int, Range: [0 to 232 - 1], Default: 0
Response:	no response

Sets the number of edges until an interrupt is invoked.

If edges is set to n, an interrupt is invoked for every n-th detected edge.

If edges is set to 0, the interrupt is disabled.

request/hall_effect_bricklet/<UID>/get_edge_interrupt¶

Request:	empty payload
Response:	edges – Type: int, Range: [0 to 232 - 1], Default: 0

Returns the edges as set by request/hall_effect_bricklet/<UID>/set_edge_interrupt.

request/hall_effect_bricklet/<UID>/set_edge_count_callback_period¶

Request:	period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:	no response

Sets the period with which the register/hall_effect_bricklet/<UID>/edge_count callback is triggered periodically. A value of 0 turns the callback off.

The register/hall_effect_bricklet/<UID>/edge_count callback is only triggered if the edge count has changed since the last triggering.

request/hall_effect_bricklet/<UID>/get_edge_count_callback_period¶

Request:	empty payload
Response:	period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by request/hall_effect_bricklet/<UID>/set_edge_count_callback_period.

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/hall_effect_bricklet/<UID>/edge_count¶

Register Request:	register – Type: bool
Callback Response:	count – Type: int, Range: [0 to 232 - 1] value – Type: bool

A callback can be registered for this event by publishing to the .../register/hall_effect_bricklet/<UID>/edge_count[/<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/hall_effect_bricklet/<UID>/edge_count[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically with the period that is set by request/hall_effect_bricklet/<UID>/set_edge_count_callback_period. The callback payload members are the current count and the current value (see request/hall_effect_bricklet/<UID>/get_value and request/hall_effect_bricklet/<UID>/get_edge_count).

The register/hall_effect_bricklet/<UID>/edge_count callback is only triggered if the count or value changed since the last triggering.