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https://github.com/zephyrproject-rtos/zephyr
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6656214af2
The board name for the nRF52 DK, so far known as nrf52_pca10040, is renamed to nrf52dk_nrf52832. Its documentation and all references to its name in the tree are updated accordingly. Overlay and configuration files specific to this board are also renamed, to match the new board name. Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
87 lines
2.9 KiB
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87 lines
2.9 KiB
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.. _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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