Python - Piezo Speaker Bricklet

This is the description of the Python API bindings for the Piezo Speaker Bricklet. General information and technical specifications for the Piezo Speaker Bricklet 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).

Beep

Download (example_beep.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 Piezo Speaker Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_piezo_speaker import BrickletPiezoSpeaker

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

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

    # Make 2 second beep with a frequency of 1kHz
    ps.beep(2000, 1000)

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

Morse Code

Download (example_morse_code.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 Piezo Speaker Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_piezo_speaker import BrickletPiezoSpeaker

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

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

    # Morse SOS with a frequency of 2kHz
    ps.morse_code("... --- ...", 2000)

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

API

Generally, every method 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.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

All methods listed below are thread-safe.

Basic Functions

BrickletPiezoSpeaker(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

piezo_speaker = BrickletPiezoSpeaker("YOUR_DEVICE_UID", ipcon)

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

BrickletPiezoSpeaker.beep(duration, frequency)
Parameters:
  • duration -- int
  • frequency -- int
Return type:

None

Beeps with the given frequency for the duration in ms. For example: If you set a duration of 1000, with a frequency value of 2000 the piezo buzzer will beep for one second with a frequency of approximately 2 kHz.

Changed in version 2.0.2 (Plugin): A duration of 0 stops the current beep if any, the frequency parameter is ignored. A duration of 4294967295 results in an infinite beep.

The frequency parameter can be set between 585 and 7100.

The Piezo Speaker Bricklet can only approximate the frequency, it will play the best possible match by applying the calibration (see calibrate()).

The following constants are available for this function:

  • BrickletPiezoSpeaker.BEEP_DURATION_OFF = 0
  • BrickletPiezoSpeaker.BEEP_DURATION_INFINITE = 4294967295
BrickletPiezoSpeaker.morse_code(morse, frequency)
Parameters:
  • morse -- str
  • frequency -- int
Return type:

None

Sets morse code that will be played by the piezo buzzer. The morse code is given as a string consisting of "." (dot), "-" (minus) and " " (space) for dits, dahs and pauses. Every other character is ignored. The second parameter is the frequency (see beep()).

For example: If you set the string "...---...", the piezo buzzer will beep nine times with the durations "short short short long long long short short short".

The maximum string size is 60.

Advanced Functions

BrickletPiezoSpeaker.calibrate()
Return type:bool

The Piezo Speaker Bricklet can play 512 different tones. This function plays each tone and measures the exact frequency back. The result is a mapping between setting value and frequency. This mapping is stored in the EEPROM and loaded on startup.

The Bricklet should come calibrated, you only need to call this function (once) every time you reflash the Bricklet plugin.

Returns true after the calibration finishes.

BrickletPiezoSpeaker.get_api_version()
Return type:[int, int, int]

Returns the version of the API definition (major, minor, revision) 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.

BrickletPiezoSpeaker.get_response_expected(function_id)
Parameters:function_id -- int
Return 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.

See set_response_expected() for the list of function ID constants available for this function.

BrickletPiezoSpeaker.set_response_expected(function_id, response_expected)
Parameters:
  • function_id -- int
  • response_expected -- bool
Return type:

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 function ID constants are available for this function:

  • BrickletPiezoSpeaker.FUNCTION_BEEP = 1
  • BrickletPiezoSpeaker.FUNCTION_MORSE_CODE = 2
BrickletPiezoSpeaker.set_response_expected_all(response_expected)
Parameters:response_expected -- bool
Return type:None

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

BrickletPiezoSpeaker.get_identity()
Return type:(str, str, chr, [int, int, int], [int, int, int], int)

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. There is also a constant for the device identifier of this Bricklet.

The returned namedtuple has the variables uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

Callback Configuration Functions

BrickletPiezoSpeaker.register_callback(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- callable
Return type:

None

Registers the given function with the given callback_id.

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

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)

piezo_speaker.register_callback(BrickletPiezoSpeaker.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.

BrickletPiezoSpeaker.CALLBACK_BEEP_FINISHED

This callback is triggered if a beep set by beep() is finished

BrickletPiezoSpeaker.CALLBACK_MORSE_CODE_FINISHED

This callback is triggered if the playback of the morse code set by morse_code() is finished.

Constants

BrickletPiezoSpeaker.DEVICE_IDENTIFIER

This constant is used to identify a Piezo Speaker Bricklet.

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

BrickletPiezoSpeaker.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Piezo Speaker Bricklet.