Modbus - Hall Effect Bricklet – Tinkerforge

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# Modbus - Hall Effect Bricklet

This is the description of the Modbus protocol for the Hall Effect Bricklet. General information and technical specifications for the Hall Effect Bricklet are summarized in its hardware description.

## API

A general description of the Modbus protocol structure can be found here.

### Basic Functions

`BrickletHallEffect.``get_value`

  Function ID: | 1
  Request: | empty payload

  Response:

  - value -- bool

  Returns true if a magnetic field of 35 Gauss (3.5mT) or greater is detected.

`BrickletHallEffect.``get_edge_count`

  Function ID: | 2

  Request:

  - reset_counter -- bool

  Response:

  - count -- uint32

  Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with `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

`BrickletHallEffect.``set_edge_count_config`

  Function ID: | 3

  Request:

  - edge_type -- uint8
  - debounce -- uint8

  Response: | no response

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

  - 0 = rising (default)
  - 1 = falling
  - 2 = both

  A magnetic field of 35 Gauss (3.5mT) or greater causes a falling edge and a magnetic field of 25 Gauss (2.5mT) 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).

  The debounce time is given in ms.

  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.

  Default values: 0 (edge type) and 100ms (debounce time)

`BrickletHallEffect.``get_edge_count_config`

  Function ID: | 4
  Request: | empty payload

  Response:

  - edge_type -- uint8
  - debounce -- uint8

  Returns the edge type and debounce time as set by `set_edge_count_config`.

`BrickletHallEffect.``get_identity`

  Function ID: | 255
  Request: | empty payload

  Response:

  - uid -- char[8]
  - connected_uid -- char[8]
  - position -- char
  - hardware_version -- uint8[3]
  - firmware_version -- uint8[3]
  - device_identifier -- uint16

  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

`BrickletHallEffect.``set_edge_interrupt`

  Function ID: | 5

  Request:

  - edges -- uint32

  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.

  Default value is 0.

`BrickletHallEffect.``get_edge_interrupt`

  Function ID: | 6
  Request: | empty payload

  Response:

  - edges -- uint32

  Returns the edges as set by `set_edge_interrupt`.

`BrickletHallEffect.``set_edge_count_callback_period`

  Function ID: | 7

  Request:

  - period -- uint32

  Response: | no response

  Sets the period in ms with which the `CALLBACK_EDGE_COUNT` callback is triggered periodically. A value of 0 turns the callback off.

  `CALLBACK_EDGE_COUNT` is only triggered if the edge count has changed since the last triggering.

  The default value is 0.

`BrickletHallEffect.``get_edge_count_callback_period`

  Function ID: | 8
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_edge_count_callback_period`.

### Callbacks

`BrickletHallEffect.``CALLBACK_EDGE_COUNT`

  Function ID: | 10

  Response:

  - count -- uint32
  - value -- bool

  This callback is triggered periodically with the period that is set by `set_edge_count_callback_period`. The response values are the current count and the current value (see `get_value` and `get_edge_count`).

  `CALLBACK_EDGE_COUNT` is only triggered if the count or value changed since the last triggering.

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