87 lines
2.9 KiB
ReStructuredText
87 lines
2.9 KiB
ReStructuredText
.. _led_ws2812_sample:
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WS2812 Sample Application
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#########################
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Overview
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********
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This sample application demonstrates basic usage of the WS2812 LED
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strip driver, for controlling LED strips using WS2812, WS2812b,
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SK6812, and compatible driver chips.
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Requirements
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************
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.. _NeoPixel Ring 12 from AdaFruit: https://www.adafruit.com/product/1643
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.. _74AHCT125: https://cdn-shop.adafruit.com/datasheets/74AHC125.pdf
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- LED strip using WS2812 or compatible, such as the `NeoPixel Ring 12
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from AdaFruit`_.
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- Note that 5V communications may require a level translator, such as the
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`74AHCT125`_.
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- LED power strip supply. It's fine to power the LED strip off of your board's
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IO voltage level even if that's below 5V; the LEDs will simply be dimmer in
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this case.
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Wiring
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******
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#. Ensure your Zephyr board, and the LED strip share a common ground.
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#. Connect the LED strip control pin (either SPI MOSI or GPIO) from your board
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to the data input pin of the first WS2812 IC in the strip.
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#. Power the LED strip at an I/O level compatible with the control pin signals.
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Building and Running
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********************
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.. _blog post on WS2812 timing: https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
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This sample's source directory is :zephyr_file:`samples/drivers/led_ws2812/`.
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To make sure the sample is set up properly for building, you must:
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- select the correct WS2812 driver backend for your SoC. This currently should
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be :option:`CONFIG_WS2812_STRIP_SPI` unless you are using an nRF51 SoC, in
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which case it will be :option:`CONFIG_WS2812_STRIP_GPIO`.
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- create a ``led-strip`` :ref:`devicetree alias <dt-alias-chosen>`, which
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refers to a node in your :ref:`devicetree <dt-guide>` with a
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``worldsemi,ws2812-spi`` or ``worldsemi,ws2812-gpio`` compatible. The node
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must be properly configured for the driver backend (SPI or GPIO) and daisy
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chain length (number of WS2812 chips).
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For example devicetree configurations for each compatible, see
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:zephyr_file:`samples/drivers/led_ws2812/boards/nrf52dk_nrf52832.overlay` and
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:zephyr_file:`samples/drivers/led_ws2812/boards/nrf51dk_nrf51422.overlay`.
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Some boards are already supported out of the box; see the :file:`boards`
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directory for this sample for details.
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Then build and flash the application:
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.. zephyr-app-commands::
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:zephyr-app: samples/drivers/led_ws2812
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:board: <board>
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:goals: flash
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:compact:
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When you connect to your board's serial console, you should see the
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following output:
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.. code-block:: none
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***** Booting Zephyr OS build v2.1.0-rc1-191-gd2466cdaf045 *****
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[00:00:00.005,920] <inf> main: Found LED strip device WS2812
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[00:00:00.005,950] <inf> main: Displaying pattern on strip
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References
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**********
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- `RGB LED strips: an overview <http://nut-bolt.nl/2012/rgb-led-strips/>`_
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- `74AHCT125 datasheet
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<https://cdn-shop.adafruit.com/datasheets/74AHC125.pdf>`_
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- An excellent `blog post on WS2812 timing`_.
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