Python - DMX Bricklet

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

Simple

Download (example_simple.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 DMX Bricklet

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_dmx import BrickletDMX

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

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

    # Configure Bricklet as DMX master
    dmx.set_dmx_mode(dmx.DMX_MODE_MASTER)

    # Write DMX frame with 3 channels
    dmx.write_frame([255, 128, 0])

    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

BrickletDMX(uid, ipcon)
Parameters:
  • uid – Type: str
  • ipcon – Type: IPConnection
Returns:
  • dmx – Type: BrickletDMX

Creates an object with the unique device ID uid:

dmx = BrickletDMX("YOUR_DEVICE_UID", ipcon)

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

BrickletDMX.set_dmx_mode(dmx_mode)
Parameters:
  • dmx_mode – Type: int, Range: See constants, Default: 0
Returns:
  • None

Sets the DMX mode to either master or slave.

Calling this function sets frame number to 0.

The following constants are available for this function:

For dmx_mode:

  • BrickletDMX.DMX_MODE_MASTER = 0
  • BrickletDMX.DMX_MODE_SLAVE = 1
BrickletDMX.get_dmx_mode()
Returns:
  • dmx_mode – Type: int, Range: See constants, Default: 0

Returns the DMX mode, as set by set_dmx_mode().

The following constants are available for this function:

For dmx_mode:

  • BrickletDMX.DMX_MODE_MASTER = 0
  • BrickletDMX.DMX_MODE_SLAVE = 1
BrickletDMX.write_frame(frame)
Parameters:
  • frame – Type: [int, ...], Length: variable, Range: [0 to 255]
Returns:
  • None

Writes a DMX frame. The maximum frame size is 512 byte. Each byte represents one channel.

The next frame can be written after the CALLBACK_FRAME_STARTED callback was called. The frame is double buffered, so a new frame can be written as soon as the writing of the prior frame starts.

The data will be transfered when the next frame duration ends, see set_frame_duration().

Generic approach:

  • Set the frame duration to a value that represents the number of frames per second you want to achieve.
  • Set channels for first frame.
  • Wait for the CALLBACK_FRAME_STARTED callback.
  • Set channels for next frame.
  • Wait for the CALLBACK_FRAME_STARTED callback.
  • and so on.

This approach ensures that you can set new DMX data with a fixed frame rate.

This function can only be called in master mode.

BrickletDMX.read_frame()
Return Object:
  • frame – Type: [int, ...], Length: variable, Range: [0 to 255]
  • frame_number – Type: int, Range: [0 to 232 - 1]

Returns the last frame that was written by the DMX master. The size of the array is equivalent to the number of channels in the frame. Each byte represents one channel.

The next frame is available after the CALLBACK_FRAME_AVAILABLE callback was called.

Generic approach:

Instead of polling this function you can also use the CALLBACK_FRAME callback. You can enable it with set_frame_callback_config().

The frame number starts at 0 and it is increased by one with each received frame.

This function can only be called in slave mode.

BrickletDMX.set_frame_duration(frame_duration)
Parameters:
  • frame_duration – Type: int, Unit: 1 ms, Range: [0 to 216 - 1], Default: 100
Returns:
  • None

Sets the duration of a frame.

Example: If you want to achieve 20 frames per second, you should set the frame duration to 50ms (50ms * 20 = 1 second).

If you always want to send a frame as fast as possible you can set this value to 0.

This setting is only used in master mode.

BrickletDMX.get_frame_duration()
Returns:
  • frame_duration – Type: int, Unit: 1 ms, Range: [0 to 216 - 1], Default: 100

Returns the frame duration as set by set_frame_duration().

Advanced Functions

BrickletDMX.get_frame_error_count()
Return Object:
  • overrun_error_count – Type: int, Range: [0 to 232 - 1]
  • framing_error_count – Type: int, Range: [0 to 232 - 1]

Returns the current number of overrun and framing errors.

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

Sets the communication LED configuration. By default the LED shows communication traffic, 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 off.

The following constants are available for this function:

For config:

  • BrickletDMX.COMMUNICATION_LED_CONFIG_OFF = 0
  • BrickletDMX.COMMUNICATION_LED_CONFIG_ON = 1
  • BrickletDMX.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDMX.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
BrickletDMX.get_communication_led_config()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_communication_led_config()

The following constants are available for this function:

For config:

  • BrickletDMX.COMMUNICATION_LED_CONFIG_OFF = 0
  • BrickletDMX.COMMUNICATION_LED_CONFIG_ON = 1
  • BrickletDMX.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDMX.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3
BrickletDMX.set_error_led_config(config)
Parameters:
  • config – Type: int, Range: See constants, Default: 3
Returns:
  • None

Sets the error LED configuration.

By default the error LED turns on if there is any error (see CALLBACK_FRAME_ERROR_COUNT callback). If you call this function with the Show-Error option again, the LED will turn off until the next error occurs.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

  • BrickletDMX.ERROR_LED_CONFIG_OFF = 0
  • BrickletDMX.ERROR_LED_CONFIG_ON = 1
  • BrickletDMX.ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDMX.ERROR_LED_CONFIG_SHOW_ERROR = 3
BrickletDMX.get_error_led_config()
Returns:
  • config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_error_led_config().

The following constants are available for this function:

For config:

  • BrickletDMX.ERROR_LED_CONFIG_OFF = 0
  • BrickletDMX.ERROR_LED_CONFIG_ON = 1
  • BrickletDMX.ERROR_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDMX.ERROR_LED_CONFIG_SHOW_ERROR = 3
BrickletDMX.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.

BrickletDMX.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:

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

For status:

  • BrickletDMX.BOOTLOADER_STATUS_OK = 0
  • BrickletDMX.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletDMX.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletDMX.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletDMX.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletDMX.BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletDMX.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:

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

BrickletDMX.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.

BrickletDMX.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:

  • BrickletDMX.STATUS_LED_CONFIG_OFF = 0
  • BrickletDMX.STATUS_LED_CONFIG_ON = 1
  • BrickletDMX.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDMX.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletDMX.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:

  • BrickletDMX.STATUS_LED_CONFIG_OFF = 0
  • BrickletDMX.STATUS_LED_CONFIG_ON = 1
  • BrickletDMX.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletDMX.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletDMX.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.

BrickletDMX.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!

BrickletDMX.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.

BrickletDMX.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.

BrickletDMX.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

BrickletDMX.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.

BrickletDMX.set_frame_callback_config(frame_started_callback_enabled, frame_available_callback_enabled, frame_callback_enabled, frame_error_count_callback_enabled)
Parameters:
  • frame_started_callback_enabled – Type: bool, Default: True
  • frame_available_callback_enabled – Type: bool, Default: True
  • frame_callback_enabled – Type: bool, Default: False
  • frame_error_count_callback_enabled – Type: bool, Default: False
Returns:
  • None

Enables/Disables the different callbacks. By default the CALLBACK_FRAME_STARTED callback and CALLBACK_FRAME_AVAILABLE callback are enabled while the CALLBACK_FRAME callback and CALLBACK_FRAME_ERROR_COUNT callback are disabled.

If you want to use the CALLBACK_FRAME callback you can enable it and disable the cb:Frame Available callback at the same time. It becomes redundant in this case.

BrickletDMX.get_frame_callback_config()
Return Object:
  • frame_started_callback_enabled – Type: bool, Default: True
  • frame_available_callback_enabled – Type: bool, Default: True
  • frame_callback_enabled – Type: bool, Default: False
  • frame_error_count_callback_enabled – Type: bool, Default: False

Returns the frame callback config as set by set_frame_callback_config().

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)

dmx.register_callback(BrickletDMX.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.

BrickletDMX.CALLBACK_FRAME_STARTED
Callback Parameters:
  • no parameters

This callback is triggered as soon as a new frame write is started. You should send the data for the next frame directly after this callback was triggered.

For an explanation of the general approach see write_frame().

This callback can be enabled via set_frame_callback_config().

This callback can only be triggered in master mode.

BrickletDMX.CALLBACK_FRAME_AVAILABLE
Callback Parameters:
  • frame_number – Type: int, Range: [0 to 232 - 1]

This callback is triggered in slave mode when a new frame was received from the DMX master and it can be read out. You have to read the frame before the master has written the next frame, see read_frame() for more details.

The parameter is the frame number, it is increased by one with each received frame.

This callback can be enabled via set_frame_callback_config().

This callback can only be triggered in slave mode.

BrickletDMX.CALLBACK_FRAME
Callback Parameters:
  • frame – Type: [int, ...], Length: variable, Range: [0 to 255]
  • frame_number – Type: int, Range: [0 to 232 - 1]

This callback is called as soon as a new frame is available (written by the DMX master).

The size of the array is equivalent to the number of channels in the frame. Each byte represents one channel.

This callback can be enabled via set_frame_callback_config().

This callback can only be triggered in slave mode.

Note

If reconstructing the value fails, the callback is triggered with None for frame.

BrickletDMX.CALLBACK_FRAME_ERROR_COUNT
Callback Parameters:
  • overrun_error_count – Type: int, Range: [0 to 232 - 1]
  • framing_error_count – Type: int, Range: [0 to 232 - 1]

This callback is called if a new error occurs. It returns the current overrun and framing error count.

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.

BrickletDMX.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.

BrickletDMX.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:

  • BrickletDMX.FUNCTION_SET_DMX_MODE = 1
  • BrickletDMX.FUNCTION_WRITE_FRAME = 3
  • BrickletDMX.FUNCTION_SET_FRAME_DURATION = 5
  • BrickletDMX.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 8
  • BrickletDMX.FUNCTION_SET_ERROR_LED_CONFIG = 10
  • BrickletDMX.FUNCTION_SET_FRAME_CALLBACK_CONFIG = 12
  • BrickletDMX.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletDMX.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletDMX.FUNCTION_RESET = 243
  • BrickletDMX.FUNCTION_WRITE_UID = 248
BrickletDMX.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:

  • BrickletDMX.FUNCTION_SET_DMX_MODE = 1
  • BrickletDMX.FUNCTION_WRITE_FRAME = 3
  • BrickletDMX.FUNCTION_SET_FRAME_DURATION = 5
  • BrickletDMX.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 8
  • BrickletDMX.FUNCTION_SET_ERROR_LED_CONFIG = 10
  • BrickletDMX.FUNCTION_SET_FRAME_CALLBACK_CONFIG = 12
  • BrickletDMX.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletDMX.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletDMX.FUNCTION_RESET = 243
  • BrickletDMX.FUNCTION_WRITE_UID = 248
BrickletDMX.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

BrickletDMX.DEVICE_IDENTIFIER

This constant is used to identify a DMX Bricklet.

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.

BrickletDMX.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a DMX Bricklet.