Python - LED Strip Bricklet 2.0

This is the description of the Python API bindings for the LED Strip Bricklet 2.0. General information and technical specifications for the LED Strip 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).

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 LED Strip Bricklet 2.0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_led_strip_v2 import BrickletLEDStripV2

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    ls = BrickletLEDStripV2(UID, ipcon) # Create device object

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

    # Set first 3 LEDs to red, green and blue
    ls.set_led_values(0, [255, 0, 0, 0, 255, 0, 0, 0, 255])

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

Callback

Download (example_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 LED Strip Bricklet 2.0
NUM_LEDS = 16

rgb = [0, 0, 0]*NUM_LEDS
index = 0

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_led_strip_v2 import BrickletLEDStripV2

# Use frame started callback to move the active LED every frame
def cb_frame_started(length, ls):
    global index

    rgb[index] = 0

    index += 3
    if index >= NUM_LEDS:
        index = 0

    rgb[index] = 255

    # Set new data for next render cycle
    ls.set_led_values(0, rgb)

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    ls = BrickletLEDStripV2(UID, ipcon) # Create device object

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

    # Set frame duration to 50ms (20 frames per second)
    ls.set_frame_duration(50)

    # Register frame rendered callback to function cb_frame_rendered
    ls.register_callback(ls.CALLBACK_FRAME_STARTED,
                         lambda x: cb_frame_started(x, ls))

    # Set initial rgb values to get started
    ls.set_led_values(0, rgb)

    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

BrickletLEDStripV2(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

led_strip_v2 = BrickletLEDStripV2("YOUR_DEVICE_UID", ipcon)

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

BrickletLEDStripV2.set_led_values(index, value)
Parameters:
  • index -- int
  • value -- [int, int, ...]
Return type:

None

Sets the RGB(W) values for the LEDs starting from index. You can set at most 2048 RGB values or 1536 RGBW values.

To make the colors show correctly you need to configure the chip type (see set_chip_type()) and a channel mapping (see set_channel_mapping()) according to the connected LEDs.

If the channel mapping has 3 colors, you need to give the data in the sequence RGBRGBRGB... if the channel mapping has 4 colors you need to give data in the sequence RGBWRGBWRGBW...

The data is double buffered and the colors will be transfered to the LEDs 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 all of the LED colors for one frame.
  • Wait for the CALLBACK_FRAME_STARTED callback.
  • Set all of the LED colors for next frame.
  • Wait for the CALLBACK_FRAME_STARTED callback.
  • And so on.

This approach ensures that you can change the LED colors with a fixed frame rate.

BrickletLEDStripV2.get_led_values(index, length)
Parameters:
  • index -- int
  • length -- int
Return type:

[int, int, ...]

Returns the RGB(W) values as set by set_led_values().

BrickletLEDStripV2.set_frame_duration(duration)
Parameters:duration -- int
Return type:None

Sets the frame duration in ms.

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

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

Default value: 100ms (10 frames per second).

BrickletLEDStripV2.get_frame_duration()
Return type:int

Returns the frame duration in ms as set by set_frame_duration().

BrickletLEDStripV2.get_supply_voltage()
Return type:int

Returns the current supply voltage of the LEDs. The voltage is given in mV.

BrickletLEDStripV2.set_clock_frequency(frequency)
Parameters:frequency -- int
Return type:None

Sets the frequency of the clock in Hz. The range is 10000Hz (10kHz) up to 2000000Hz (2MHz).

The Bricklet will choose the nearest achievable frequency, which may be off by a few Hz. You can get the exact frequency that is used by calling get_clock_frequency().

If you have problems with flickering LEDs, they may be bits flipping. You can fix this by either making the connection between the LEDs and the Bricklet shorter or by reducing the frequency.

With a decreasing frequency your maximum frames per second will decrease too.

The default value is 1.66MHz.

BrickletLEDStripV2.get_clock_frequency()
Return type:int

Returns the currently used clock frequency as set by set_clock_frequency().

BrickletLEDStripV2.set_chip_type(chip)
Parameters:chip -- int
Return type:None

Sets the type of the LED driver chip. We currently support the chips

  • WS2801,
  • WS2811,
  • WS2812 / SK6812 / NeoPixel RGB,
  • SK6812RGBW / NeoPixel RGBW (Chip Type = WS2812),
  • LPD8806 and
  • APA102 / DotStar.

The default value is WS2801 (2801).

The following constants are available for this function:

  • BrickletLEDStripV2.CHIP_TYPE_WS2801 = 2801
  • BrickletLEDStripV2.CHIP_TYPE_WS2811 = 2811
  • BrickletLEDStripV2.CHIP_TYPE_WS2812 = 2812
  • BrickletLEDStripV2.CHIP_TYPE_LPD8806 = 8806
  • BrickletLEDStripV2.CHIP_TYPE_APA102 = 102
BrickletLEDStripV2.get_chip_type()
Return type:int

Returns the currently used chip type as set by set_chip_type().

The following constants are available for this function:

  • BrickletLEDStripV2.CHIP_TYPE_WS2801 = 2801
  • BrickletLEDStripV2.CHIP_TYPE_WS2811 = 2811
  • BrickletLEDStripV2.CHIP_TYPE_WS2812 = 2812
  • BrickletLEDStripV2.CHIP_TYPE_LPD8806 = 8806
  • BrickletLEDStripV2.CHIP_TYPE_APA102 = 102
BrickletLEDStripV2.set_channel_mapping(mapping)
Parameters:mapping -- int
Return type:None

Sets the channel mapping for the connected LEDs.

If the mapping has 4 colors, the function set_led_values() expects 4 values per pixel and if the mapping has 3 colors it expects 3 values per pixel.

The function always expects the order RGB(W). The connected LED driver chips might have their 3 or 4 channels in a different order. For example, the WS2801 chips typically use BGR order, then WS2812 chips typically use GRB order and the APA102 chips typically use WBGR order.

The APA102 chips are special. They have three 8-bit channels for RGB and an additional 5-bit channel for the overall brightness of the RGB LED making them 4-channel chips. Internally the brightness channel is the first channel, therefore one of the Wxyz channel mappings should be used. Then the W channel controls the brightness.

The default value is BGR (36).

The following constants are available for this function:

  • BrickletLEDStripV2.CHANNEL_MAPPING_RGB = 6
  • BrickletLEDStripV2.CHANNEL_MAPPING_RBG = 9
  • BrickletLEDStripV2.CHANNEL_MAPPING_BRG = 33
  • BrickletLEDStripV2.CHANNEL_MAPPING_BGR = 36
  • BrickletLEDStripV2.CHANNEL_MAPPING_GRB = 18
  • BrickletLEDStripV2.CHANNEL_MAPPING_GBR = 24
  • BrickletLEDStripV2.CHANNEL_MAPPING_RGBW = 27
  • BrickletLEDStripV2.CHANNEL_MAPPING_RGWB = 30
  • BrickletLEDStripV2.CHANNEL_MAPPING_RBGW = 39
  • BrickletLEDStripV2.CHANNEL_MAPPING_RBWG = 45
  • BrickletLEDStripV2.CHANNEL_MAPPING_RWGB = 54
  • BrickletLEDStripV2.CHANNEL_MAPPING_RWBG = 57
  • BrickletLEDStripV2.CHANNEL_MAPPING_GRWB = 78
  • BrickletLEDStripV2.CHANNEL_MAPPING_GRBW = 75
  • BrickletLEDStripV2.CHANNEL_MAPPING_GBWR = 108
  • BrickletLEDStripV2.CHANNEL_MAPPING_GBRW = 99
  • BrickletLEDStripV2.CHANNEL_MAPPING_GWBR = 120
  • BrickletLEDStripV2.CHANNEL_MAPPING_GWRB = 114
  • BrickletLEDStripV2.CHANNEL_MAPPING_BRGW = 135
  • BrickletLEDStripV2.CHANNEL_MAPPING_BRWG = 141
  • BrickletLEDStripV2.CHANNEL_MAPPING_BGRW = 147
  • BrickletLEDStripV2.CHANNEL_MAPPING_BGWR = 156
  • BrickletLEDStripV2.CHANNEL_MAPPING_BWRG = 177
  • BrickletLEDStripV2.CHANNEL_MAPPING_BWGR = 180
  • BrickletLEDStripV2.CHANNEL_MAPPING_WRBG = 201
  • BrickletLEDStripV2.CHANNEL_MAPPING_WRGB = 198
  • BrickletLEDStripV2.CHANNEL_MAPPING_WGBR = 216
  • BrickletLEDStripV2.CHANNEL_MAPPING_WGRB = 210
  • BrickletLEDStripV2.CHANNEL_MAPPING_WBGR = 228
  • BrickletLEDStripV2.CHANNEL_MAPPING_WBRG = 225
BrickletLEDStripV2.get_channel_mapping()
Return type:int

Returns the currently used channel mapping as set by set_channel_mapping().

The following constants are available for this function:

  • BrickletLEDStripV2.CHANNEL_MAPPING_RGB = 6
  • BrickletLEDStripV2.CHANNEL_MAPPING_RBG = 9
  • BrickletLEDStripV2.CHANNEL_MAPPING_BRG = 33
  • BrickletLEDStripV2.CHANNEL_MAPPING_BGR = 36
  • BrickletLEDStripV2.CHANNEL_MAPPING_GRB = 18
  • BrickletLEDStripV2.CHANNEL_MAPPING_GBR = 24
  • BrickletLEDStripV2.CHANNEL_MAPPING_RGBW = 27
  • BrickletLEDStripV2.CHANNEL_MAPPING_RGWB = 30
  • BrickletLEDStripV2.CHANNEL_MAPPING_RBGW = 39
  • BrickletLEDStripV2.CHANNEL_MAPPING_RBWG = 45
  • BrickletLEDStripV2.CHANNEL_MAPPING_RWGB = 54
  • BrickletLEDStripV2.CHANNEL_MAPPING_RWBG = 57
  • BrickletLEDStripV2.CHANNEL_MAPPING_GRWB = 78
  • BrickletLEDStripV2.CHANNEL_MAPPING_GRBW = 75
  • BrickletLEDStripV2.CHANNEL_MAPPING_GBWR = 108
  • BrickletLEDStripV2.CHANNEL_MAPPING_GBRW = 99
  • BrickletLEDStripV2.CHANNEL_MAPPING_GWBR = 120
  • BrickletLEDStripV2.CHANNEL_MAPPING_GWRB = 114
  • BrickletLEDStripV2.CHANNEL_MAPPING_BRGW = 135
  • BrickletLEDStripV2.CHANNEL_MAPPING_BRWG = 141
  • BrickletLEDStripV2.CHANNEL_MAPPING_BGRW = 147
  • BrickletLEDStripV2.CHANNEL_MAPPING_BGWR = 156
  • BrickletLEDStripV2.CHANNEL_MAPPING_BWRG = 177
  • BrickletLEDStripV2.CHANNEL_MAPPING_BWGR = 180
  • BrickletLEDStripV2.CHANNEL_MAPPING_WRBG = 201
  • BrickletLEDStripV2.CHANNEL_MAPPING_WRGB = 198
  • BrickletLEDStripV2.CHANNEL_MAPPING_WGBR = 216
  • BrickletLEDStripV2.CHANNEL_MAPPING_WGRB = 210
  • BrickletLEDStripV2.CHANNEL_MAPPING_WBGR = 228
  • BrickletLEDStripV2.CHANNEL_MAPPING_WBRG = 225

Advanced Functions

BrickletLEDStripV2.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.

BrickletLEDStripV2.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.

BrickletLEDStripV2.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:

  • BrickletLEDStripV2.FUNCTION_SET_LED_VALUES = 1
  • BrickletLEDStripV2.FUNCTION_SET_FRAME_DURATION = 3
  • BrickletLEDStripV2.FUNCTION_SET_CLOCK_FREQUENCY = 7
  • BrickletLEDStripV2.FUNCTION_SET_CHIP_TYPE = 9
  • BrickletLEDStripV2.FUNCTION_SET_CHANNEL_MAPPING = 11
  • BrickletLEDStripV2.FUNCTION_SET_FRAME_STARTED_CALLBACK_CONFIGURATION = 13
  • BrickletLEDStripV2.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickletLEDStripV2.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickletLEDStripV2.FUNCTION_RESET = 243
  • BrickletLEDStripV2.FUNCTION_WRITE_UID = 248
BrickletLEDStripV2.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.

BrickletLEDStripV2.get_spitfp_error_count()
Return type:(int, int, int, int)

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.

The returned namedtuple has the variables error_count_ack_checksum, error_count_message_checksum, error_count_frame and error_count_overflow.

BrickletLEDStripV2.set_bootloader_mode(mode)
Parameters:mode -- int
Return type:int

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:

  • BrickletLEDStripV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletLEDStripV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletLEDStripV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletLEDStripV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletLEDStripV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickletLEDStripV2.BOOTLOADER_STATUS_OK = 0
  • BrickletLEDStripV2.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickletLEDStripV2.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickletLEDStripV2.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickletLEDStripV2.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickletLEDStripV2.BOOTLOADER_STATUS_CRC_MISMATCH = 5
BrickletLEDStripV2.get_bootloader_mode()
Return type:int

Returns the current bootloader mode, see set_bootloader_mode().

The following constants are available for this function:

  • BrickletLEDStripV2.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickletLEDStripV2.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickletLEDStripV2.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickletLEDStripV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickletLEDStripV2.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
BrickletLEDStripV2.set_write_firmware_pointer(pointer)
Parameters:pointer -- int
Return type: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.

BrickletLEDStripV2.write_firmware(data)
Parameters:data -- [int, int, ..61x.., int]
Return type:int

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.

BrickletLEDStripV2.set_status_led_config(config)
Parameters:config -- int
Return type: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:

  • BrickletLEDStripV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletLEDStripV2.STATUS_LED_CONFIG_ON = 1
  • BrickletLEDStripV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletLEDStripV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletLEDStripV2.get_status_led_config()
Return type:int

Returns the configuration as set by set_status_led_config()

The following constants are available for this function:

  • BrickletLEDStripV2.STATUS_LED_CONFIG_OFF = 0
  • BrickletLEDStripV2.STATUS_LED_CONFIG_ON = 1
  • BrickletLEDStripV2.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickletLEDStripV2.STATUS_LED_CONFIG_SHOW_STATUS = 3
BrickletLEDStripV2.get_chip_temperature()
Return type:int

Returns the temperature in °C 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.

BrickletLEDStripV2.reset()
Return type: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!

BrickletLEDStripV2.write_uid(uid)
Parameters:uid -- int
Return type: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.

BrickletLEDStripV2.read_uid()
Return type:int

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

BrickletLEDStripV2.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

BrickletLEDStripV2.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.

BrickletLEDStripV2.set_frame_started_callback_configuration(enable)
Parameters:enable -- bool
Return type:None

Enables/disables the CALLBACK_FRAME_STARTED callback.

By default the callback is enabled.

BrickletLEDStripV2.get_frame_started_callback_configuration()
Return type:bool

Returns the configuration as set by set_frame_started_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)

led_strip_v2.register_callback(BrickletLEDStripV2.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.

BrickletLEDStripV2.CALLBACK_FRAME_STARTED
Parameters:length -- int

This callback is triggered directly after a new frame render is started. The parameter is the number of LEDs in that frame.

You should send the data for the next frame directly after this callback was triggered.

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

Constants

BrickletLEDStripV2.DEVICE_IDENTIFIER

This constant is used to identify a LED Strip Bricklet 2.0.

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.

BrickletLEDStripV2.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a LED Strip Bricklet 2.0.