Python - Hall Effect Bricklet 2.0

This is the description of the Python API bindings for the Hall Effect Bricklet 2.0. General information and technical specifications for the Hall Effect Bricklet 2.0 are summarized in its hardware description.

An installation guide for the Python API bindings is part of their general description.

Examples

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

Counter

Download (example_counter.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Hall Effect Bricklet 2.0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_hall_effect_v2 import BrickletHallEffectV2

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    he = BrickletHallEffectV2(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Get current count without counter reset
    count = he.get_counter(False)
    print("Count: " + str(count))

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Magnetic Flux Density

Download (example_magnetic_flux_density.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Hall Effect Bricklet 2.0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_hall_effect_v2 import BrickletHallEffectV2

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    he = BrickletHallEffectV2(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Get current Magnetic Flux Density
    magnetic_flux_density = he.get_magnetic_flux_density()
    print("Magnetic Flux Density: " + str(magnetic_flux_density) + " µT")

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

Counter Callback

Download (example_counter_callback.py)

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your Hall Effect Bricklet 2.0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_hall_effect_v2 import BrickletHallEffectV2

# Callback function for counter callback
def cb_counter(counter):
    print("Counter: " + str(counter))

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    he = BrickletHallEffectV2(UID, ipcon) # Create device object

    ipcon.connect(HOST, PORT) # Connect to brickd
    # Don't use device before ipcon is connected

    # Configure counter with ±3000µT threshold and 10ms debounce
    he.set_counter_config(3000, -3000, 10000)

    # Register counter callback to function cb_counter
    he.register_callback(he.CALLBACK_COUNTER, cb_counter)

    # Set period for counter callback to 0.1s (100ms)
    he.set_counter_callback_configuration(100, True)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

API

Generally, every function of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:

  • Error.TIMEOUT = -1
  • Error.NOT_ADDED = -6 (unused since Python bindings version 2.0.0)
  • Error.ALREADY_CONNECTED = -7
  • Error.NOT_CONNECTED = -8
  • Error.INVALID_PARAMETER = -9
  • Error.NOT_SUPPORTED = -10
  • Error.UNKNOWN_ERROR_CODE = -11
  • Error.STREAM_OUT_OF_SYNC = -12
  • Error.INVALID_UID = -13
  • Error.NON_ASCII_CHAR_IN_SECRET = -14

All functions listed below are thread-safe.

Basic Functions

BrickletHallEffectV2(uid, ipcon)
Parameters:
  • uid – Type: str
  • ipcon – Type: IPConnection
Returns:
  • hall_effect_v2 – Type: BrickletHallEffectV2

Creates an object with the unique device ID uid:

hall_effect_v2 = BrickletHallEffectV2("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected (see examples above).

BrickletHallEffectV2.get_magnetic_flux_density()
Returns:
  • magnetic_flux_density – Type: int, Unit: 1 µT, Range: [-7000 to 7000]

Returns the magnetic flux density (magnetic induction).

If you want to get the value periodically, it is recommended to use the CALLBACK_MAGNETIC_FLUX_DENSITY callback. You can set the callback configuration with set_magnetic_flux_density_callback_configuration().

BrickletHallEffectV2.get_counter(reset_counter)
Parameters:
  • reset_counter – Type: bool
Returns:
  • count – Type: int, Range: [0 to 232 - 1]

Returns the current value of the counter.

You can configure the low/high thresholds and the debounce time with set_counter_config().

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

If you want to get the count periodically, it is recommended to use the CALLBACK_COUNTER callback. You can set the callback configuration with set_counter_callback_configuration().

BrickletHallEffectV2.set_counter_config(high_threshold, low_threshold, debounce)
Parameters:
  • high_threshold – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: 2000
  • low_threshold – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: -2000
  • debounce – Type: int, Unit: 1 µs, Range: [0 to 1000000], Default: 100000
Returns:
  • None

Sets a high and a low threshold as well as a debounce time.

If the measured magnetic flux density goes above the high threshold or below the low threshold, the count of the counter is increased by 1.

The debounce time is the minimum time between two count increments.

BrickletHallEffectV2.get_counter_config()
Return Object:
  • high_threshold – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: 2000
  • low_threshold – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: -2000
  • debounce – Type: int, Unit: 1 µs, Range: [0 to 1000000], Default: 100000

Returns the counter config as set by set_counter_config().

Advanced Functions

BrickletHallEffectV2.get_spitfp_error_count()
Return Object:
  • error_count_ack_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_frame – Type: int, Range: [0 to 232 - 1]
  • error_count_overflow – Type: int, Range: [0 to 232 - 1]

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.

BrickletHallEffectV2.set_bootloader_mode(mode)
Parameters:
  • mode – Type: int, Range: See constants
Returns:
  • status – Type: int, Range: See constants

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 constants are available for this function:

For mode:

  • BrickletHallEffectV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletHallEffectV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletHallEffectV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletHallEffectV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletHallEffectV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For status:

  • BrickletHallEffectV2.BOOTLOADER_STATUS_OK = 0
  • BrickletHallEffectV2.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletHallEffectV2.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletHallEffectV2.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletHallEffectV2.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletHallEffectV2.BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletHallEffectV2.get_bootloader_mode()
Returns:
  • mode – Type: int, Range: See constants

Returns the current bootloader mode, see set_bootloader_mode().

The following constants are available for this function:

For mode:

  • BrickletHallEffectV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletHallEffectV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletHallEffectV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletHallEffectV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletHallEffectV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
BrickletHallEffectV2.set_write_firmware_pointer(pointer)
Parameters:
  • pointer – Type: int, Unit: 1 B, Range: [0 to 232 - 1]
Returns:
  • None

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.

BrickletHallEffectV2.write_firmware(data)
Parameters:
  • data – Type: [int, ...], Length: 64, Range: [0 to 255]
Returns:
  • status – Type: int, Range: [0 to 255]

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.

BrickletHallEffectV2.set_status_led_config(config)
Parameters:
  • config – Type: int, Range: See constants, Default: 3
Returns:
  • None

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 constants are available for this function:

For config:

  • BrickletHallEffectV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletHallEffectV2.STATUS_LED_CONFIG_ON = 1
  • BrickletHallEffectV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletHallEffectV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletHallEffectV2.get_status_led_config()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_status_led_config()

The following constants are available for this function:

For config:

  • BrickletHallEffectV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletHallEffectV2.STATUS_LED_CONFIG_ON = 1
  • BrickletHallEffectV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletHallEffectV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletHallEffectV2.get_chip_temperature()
Returns:
  • temperature – Type: int, Unit: 1 °C, Range: [-215 to 215 - 1]

Returns the temperature 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.

BrickletHallEffectV2.reset()
Returns:
  • None

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!

BrickletHallEffectV2.write_uid(uid)
Parameters:
  • uid – Type: int, Range: [0 to 232 - 1]
Returns:
  • None

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.

BrickletHallEffectV2.read_uid()
Returns:
  • uid – Type: int, Range: [0 to 232 - 1]

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

BrickletHallEffectV2.get_identity()
Return Object:
  • uid – Type: str, Length: up to 8
  • connected_uid – Type: str, Length: up to 8
  • position – Type: chr, Range: ["a" to "h", "i", "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]

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). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

BrickletHallEffectV2.register_callback(callback_id, function)
Parameters:
  • callback_id – Type: int
  • function – Type: callable
Returns:
  • None

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletHallEffectV2.set_magnetic_flux_density_callback_configuration(period, value_has_to_change, option, min, max)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: False
  • option – Type: chr, Range: See constants, Default: "x"
  • min – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: 0
  • max – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: 0
Returns:
  • None

The period is the period with which the CALLBACK_MAGNETIC_FLUX_DENSITY 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.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the CALLBACK_MAGNETIC_FLUX_DENSITY callback.

The following options are possible:

Option Description
'x' Threshold is turned off
'o' Threshold is triggered when the value is outside the min and max values
'i' Threshold is triggered when the value is inside or equal to the min and max values
'<' Threshold is triggered when the value is smaller than the min value (max is ignored)
'>' Threshold is triggered when the value is greater than the min value (max is ignored)

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

The following constants are available for this function:

For option:

  • BrickletHallEffectV2.THRESHOLD_OPTION_OFF = "x"
  • BrickletHallEffectV2.THRESHOLD_OPTION_OUTSIDE = "o"
  • BrickletHallEffectV2.THRESHOLD_OPTION_INSIDE = "i"
  • BrickletHallEffectV2.THRESHOLD_OPTION_SMALLER = "<"
  • BrickletHallEffectV2.THRESHOLD_OPTION_GREATER = ">"
BrickletHallEffectV2.get_magnetic_flux_density_callback_configuration()
Return Object:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: False
  • option – Type: chr, Range: See constants, Default: "x"
  • min – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: 0
  • max – Type: int, Unit: 1 µT, Range: [-215 to 215 - 1], Default: 0

Returns the callback configuration as set by set_magnetic_flux_density_callback_configuration().

The following constants are available for this function:

For option:

  • BrickletHallEffectV2.THRESHOLD_OPTION_OFF = "x"
  • BrickletHallEffectV2.THRESHOLD_OPTION_OUTSIDE = "o"
  • BrickletHallEffectV2.THRESHOLD_OPTION_INSIDE = "i"
  • BrickletHallEffectV2.THRESHOLD_OPTION_SMALLER = "<"
  • BrickletHallEffectV2.THRESHOLD_OPTION_GREATER = ">"
BrickletHallEffectV2.set_counter_callback_configuration(period, value_has_to_change)
Parameters:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: False
Returns:
  • None

The period is the period with which the CALLBACK_COUNTER 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 at least one of the values has changed. If the values 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.

BrickletHallEffectV2.get_counter_callback_configuration()
Return Object:
  • period – Type: int, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: False

Returns the callback configuration as set by set_counter_callback_configuration().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

hall_effect_v2.register_callback(BrickletHallEffectV2.CALLBACK_EXAMPLE, my_callback)

The available constants with inherent number and type of parameters 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.

BrickletHallEffectV2.CALLBACK_MAGNETIC_FLUX_DENSITY
Callback Parameters:
  • magnetic_flux_density – Type: int, Unit: 1 µT, Range: [-7000 to 7000]

This callback is triggered periodically according to the configuration set by set_magnetic_flux_density_callback_configuration().

The parameter is the same as get_magnetic_flux_density().

BrickletHallEffectV2.CALLBACK_COUNTER
Callback Parameters:
  • count – Type: int, Range: [0 to 232 - 1]

This callback is triggered periodically according to the configuration set by set_counter_callback_configuration().

The count is the same as you would get with get_counter().

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

BrickletHallEffectV2.get_api_version()
Return Object:
  • api_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]

Returns the version of the API definition implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

BrickletHallEffectV2.get_response_expected(function_id)
Parameters:
  • function_id – Type: int, Range: See constants
Returns:
  • response_expected – Type: bool

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by set_response_expected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletHallEffectV2.FUNCTION_SET_MAGNETIC_FLUX_DENSITY_CALLBACK_CONFIGURATION = 2
  • BrickletHallEffectV2.FUNCTION_SET_COUNTER_CONFIG = 6
  • BrickletHallEffectV2.FUNCTION_SET_COUNTER_CALLBACK_CONFIGURATION = 8
  • BrickletHallEffectV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletHallEffectV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletHallEffectV2.FUNCTION_RESET = 243
  • BrickletHallEffectV2.FUNCTION_WRITE_UID = 248
BrickletHallEffectV2.set_response_expected(function_id, response_expected)
Parameters:
  • function_id – Type: int, Range: See constants
  • response_expected – Type: bool
Returns:
  • None

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

  • BrickletHallEffectV2.FUNCTION_SET_MAGNETIC_FLUX_DENSITY_CALLBACK_CONFIGURATION = 2
  • BrickletHallEffectV2.FUNCTION_SET_COUNTER_CONFIG = 6
  • BrickletHallEffectV2.FUNCTION_SET_COUNTER_CALLBACK_CONFIGURATION = 8
  • BrickletHallEffectV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletHallEffectV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletHallEffectV2.FUNCTION_RESET = 243
  • BrickletHallEffectV2.FUNCTION_WRITE_UID = 248
BrickletHallEffectV2.set_response_expected_all(response_expected)
Parameters:
  • response_expected – Type: bool
Returns:
  • None

Changes the response expected flag for all setter and callback configuration functions of this device at once.

Constants

BrickletHallEffectV2.DEVICE_IDENTIFIER

This constant is used to identify a Hall Effect Bricklet 2.0.

The get_identity() function and the IPConnection.CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletHallEffectV2.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Hall Effect Bricklet 2.0.