This is the description of the Modbus protocol for the LED Strip Bricklet. General information and technical specifications for the LED Strip Bricklet are summarized in its hardware description.
A general description of the Modbus protocol structure can be found here.
Function ID: | 1 |
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Request: |
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Response: | no response |
Sets the rgb values for the LEDs with the given length starting from index.
The maximum length is 16, the index goes from 0 to 319 and the rgb values have 8 bits each.
Example: If you set
the LED with index 5 will be red, 6 will be green and 7 will be blue.
Note
Depending on the LED circuitry colors can be permuted.
The colors will be transfered to actual LEDs when the next frame duration ends, see set_frame_duration.
Generic approach:
This approach ensures that you can change the LED colors with a fixed frame rate.
The actual number of controllable LEDs depends on the number of free Bricklet ports. See here for more information. A call of set_rgb_values with index + length above the bounds is ignored completely.
Function ID: | 2 |
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Request: |
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Response: |
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Returns the rgb with the given length starting from the given index.
The values are the last values that were set by set_rgb_values.
Function ID: | 3 |
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Request: |
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Response: | no response |
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_rgb_values.
Default value: 100ms (10 frames per second).
Function ID: | 4 |
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Request: | empty payload |
Response: |
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Returns the frame duration as set by set_frame_duration.
Function ID: | 5 |
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Request: | empty payload |
Response: |
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Returns the current supply voltage of the LEDs. The voltage is given in mV.
Function ID: | 7 |
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Request: |
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Response: | no response |
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.
Note
The frequency in firmware version 2.0.0 is fixed at 2MHz.
New in version 2.0.1 (Plugin).
Function ID: | 8 |
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Request: | empty payload |
Response: |
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Returns the currently used clock frequency as set by set_clock_frequency.
New in version 2.0.1 (Plugin).
Function ID: | 9 |
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Request: |
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Response: | no response |
Sets the type of the led driver chip. We currently support the chips
The WS2812 is sometimes also called "NeoPixel", a name coined by Adafruit.
The default value is WS2801 (chip = 2801).
New in version 2.0.2 (Plugin).
Function ID: | 10 |
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Request: | empty payload |
Response: |
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Returns the currently used chip type as set by set_chip_type.
New in version 2.0.2 (Plugin).
Function ID: | 255 |
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Request: | empty payload |
Response: |
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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.
Function ID: | 6 |
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Response: |
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This callback is triggered directly after a new frame is rendered.
You should send the data for the next frame directly after this callback was triggered.
For an explanation of the general approach see set_rgb_values.