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The physical nRF51dk / nRF51dongle hardware contains a nRF51422 SoC. In Zephyr, only the nRF51822 SoC, is implemented. In Zephyr, the nRF51422 SoC is build as a nRF51822, therefore use the nRF51822 SoC model for those kits instead on the non-existing nRF51422. Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
130 lines
4.3 KiB
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130 lines
4.3 KiB
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.. zephyr:code-sample:: led-ws2812
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:name: WS2812 LED strip
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:relevant-api: led_strip_interface
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Control an LED strip using a WS2812 (or compatible) driver chip.
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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, Everlight B1414 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 I2S SDOUT, SPI MOSI or GPIO) from
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your board 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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Wiring on a thingy52
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********************
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The thingy52 has integrated NMOS transistors, that can be used instead of a level shifter.
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The I2S driver supports inverting the output to suit this scheme, using the ``out-active-low`` dts
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property. See the overlay file
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:zephyr_file:`samples/drivers/led_ws2812/boards/thingy52_nrf52832.overlay` for more detail.
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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 :kconfig:option:`CONFIG_WS2812_STRIP_SPI` unless you are using an nRF51 SoC, in
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which case it will be :kconfig:option:`CONFIG_WS2812_STRIP_GPIO`.
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For the nRF52832, the SPI peripheral might output some garbage at the end of
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transmissions, and that might confuse older WS2812 strips. Use the I2S driver
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in those cases.
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- create a ``led-strip`` :ref:`devicetree alias <dt-alias-chosen>`, which refers
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to a node in your :ref:`devicetree <dt-guide>` with a
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``worldsemi,ws2812-i2s``, ``worldsemi,ws2812-spi`` or
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``worldsemi,ws2812-gpio`` compatible. The node must be properly configured for
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the driver backend (I2S, SPI or GPIO) and daisy chain length (number of WS2812
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chips).
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For example devicetree configurations for each compatible, see
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:zephyr_file:`samples/drivers/led_ws2812/boards/thingy52_nrf52832.overlay`,
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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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The sample updates the LED strip periodically. The update frequency can be
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modified by changing the :kconfig:option:`CONFIG_SAMPLE_LED_UPDATE_DELAY`.
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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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Supported drivers
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*****************
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This sample uses different drivers depending on the selected board:
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I2S driver:
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- thingy52/nrf52832
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- nrf5340dk/nrf5340 (3.3V logic level, a logic level shifter may be required)
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- should work for other boards featuring an nRF5340 host processor
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SPI driver:
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- mimxrt1050_evk
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- mimxrt1050_evk_qspi
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- nrf52dk/nrf52832
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- nucleo_f070rb
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- nucleo_g071rb
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- nucleo_h743zi
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- nucleo_l476rg
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GPIO driver (cortex-M0 only):
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- bbc_microbit
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- nrf51dk/nrf51822
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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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