Shell - Hall Effect Bricklet

This is the description of the Shell API bindings for the Hall Effect Bricklet. General information and technical specifications for the Hall Effect Bricklet 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 Hall Effect Bricklet

# Get current edge count without reset
tinkerforge call hall-effect-bricklet $uid get-edge-count false

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 Hall Effect Bricklet

# Handle incoming edge count callbacks
tinkerforge dispatch hall-effect-bricklet $uid edge-count &

# 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!
tinkerforge call hall-effect-bricklet $uid set-edge-count-callback-period 50

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 hall-effect-bricklet [<option>..] <uid> <function> [<argument>..]
Parameters:
  • <uid> -- string
  • <function> -- string

The call command is used to call a function of the Hall Effect Bricklet. 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 Hall Effect Bricklet and exits
tinkerforge dispatch hall-effect-bricklet [<option>..] <uid> <callback>
Parameters:
  • <uid> -- string
  • <callback> -- string

The dispatch command is used to dispatch a callback of the Hall Effect Bricklet. 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 Hall Effect Bricklet and exits
tinkerforge call hall-effect-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 hall-effect-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 hall-effect-bricklet <uid> get-value
Output:
  • value -- bool

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

tinkerforge call hall-effect-bricklet <uid> get-edge-count <reset-counter>
Parameters:
  • <reset-counter> -- bool
Output:
  • count -- int

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

tinkerforge call hall-effect-bricklet <uid> set-edge-count-config <edge-type> <debounce>
Parameters:
  • <edge-type> -- int (has symbols)
  • <debounce> -- int
Output:

no output

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)

The following symbols are available for this function:

  • edge-type-rising = 0, for <edge-type>
  • edge-type-falling = 1, for <edge-type>
  • edge-type-both = 2, for <edge-type>
tinkerforge call hall-effect-bricklet <uid> get-edge-count-config
Output:
  • edge-type -- int (has symbols)
  • debounce -- int

Returns the edge type and debounce time as set by set-edge-count-config.

The following symbols are available for this function:

  • edge-type-rising = 0, for edge-type
  • edge-type-falling = 1, for edge-type
  • edge-type-both = 2, for edge-type
tinkerforge call hall-effect-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 hall-effect-bricklet <uid> set-edge-interrupt <edges>
Parameters:
  • <edges> -- int
Output:

no output

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.

tinkerforge call hall-effect-bricklet <uid> get-edge-interrupt
Output:
  • edges -- int

Returns the edges as set by set-edge-interrupt.

tinkerforge call hall-effect-bricklet <uid> set-edge-count-callback-period <period>
Parameters:
  • <period> -- int
Output:

no output

Sets the period in ms with which the edge-count callback is triggered periodically. A value of 0 turns the callback off.

The edge-count callback is only triggered if the edge count has changed since the last triggering.

The default value is 0.

tinkerforge call hall-effect-bricklet <uid> get-edge-count-callback-period
Output:
  • period -- int

Returns the period as set by set-edge-count-callback-period.

Callbacks

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

tinkerforge dispatch hall-effect-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 hall-effect-bricklet <uid> edge-count
Output:
  • count -- int
  • value -- bool

This callback is triggered periodically with the period that is set by set-edge-count-callback-period. The parameters are the current count and the current value (see get-value and get-edge-count).

The edge-count callback is only triggered if the count or value changed since the last triggering.