zephyr

History

Simon Guinot d20466d525 samples: led_ws2812: fix dma property in nucleo_f070rb.overlay Since commit `718c77a4cd` ("dts: arm: stm32f0 soc serie has dma of type V2bis"), the DMA DT cell of STM32F0 MCU has been fixed. It now has three elements instead of five previously. This patch fixes the dma property used in nucleo_f070rb.overlay accordingly. Signed-off-by: Simon Guinot <simon.guinot@seagate.com>		2021-09-13 11:55:51 -04:00
..
boards	samples: led_ws2812: fix dma property in nucleo_f070rb.overlay	2021-09-13 11:55:51 -04:00
src	samples: led_ws2812: drop device_get_binding	2021-05-05 20:46:43 +02:00
CMakeLists.txt	cmake: increase minimal required version to 3.20.0	2021-08-20 09:47:34 +02:00
Kconfig	…
README.rst	samples: led_ws2812: add example for Everlight B1414	2021-07-20 13:35:02 +02:00
f070rb-bindings.h	samples: led_ws2812: add example for Everlight B1414	2021-07-20 13:35:02 +02:00
nrf52-bindings.h	…
prj.conf	…
sample.yaml	sanitycheck: inclusive language	2020-08-27 07:04:07 -04:00

README.rst

.. _led_ws2812_sample:

WS2812 Sample Application
#########################

Overview
********

This sample application demonstrates basic usage of the WS2812 LED
strip driver, for controlling LED strips using WS2812, WS2812b,
SK6812, Everlight B1414 and compatible driver chips.

Requirements
************

.. _NeoPixel Ring 12 from AdaFruit: https://www.adafruit.com/product/1643
.. _74AHCT125: https://cdn-shop.adafruit.com/datasheets/74AHC125.pdf

- LED strip using WS2812 or compatible, such as the `NeoPixel Ring 12
from AdaFruit`_.

- Note that 5V communications may require a level translator, such as the
`74AHCT125`_.

- LED power strip supply. It's fine to power the LED strip off of your board's
IO voltage level even if that's below 5V; the LEDs will simply be dimmer in
this case.

Wiring
******

#. Ensure your Zephyr board, and the LED strip share a common ground.
#. Connect the LED strip control pin (either SPI MOSI or GPIO) from your board
to the data input pin of the first WS2812 IC in the strip.
#. Power the LED strip at an I/O level compatible with the control pin signals.

Building and Running
********************

.. _blog post on WS2812 timing: https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/

This sample's source directory is :zephyr_file:`samples/drivers/led_ws2812/`.

To make sure the sample is set up properly for building, you must:

- select the correct WS2812 driver backend for your SoC. This currently should
be :kconfig:`CONFIG_WS2812_STRIP_SPI` unless you are using an nRF51 SoC, in
which case it will be :kconfig:`CONFIG_WS2812_STRIP_GPIO`.

- create a ``led-strip`` :ref:`devicetree alias <dt-alias-chosen>`, which
refers to a node in your :ref:`devicetree <dt-guide>` with a
``worldsemi,ws2812-spi`` or ``worldsemi,ws2812-gpio`` compatible. The node
must be properly configured for the driver backend (SPI or GPIO) and daisy
chain length (number of WS2812 chips).

For example devicetree configurations for each compatible, see
:zephyr_file:`samples/drivers/led_ws2812/boards/nrf52dk_nrf52832.overlay` and
:zephyr_file:`samples/drivers/led_ws2812/boards/nrf51dk_nrf51422.overlay`.

Some boards are already supported out of the box; see the :file:`boards`
directory for this sample for details.

Then build and flash the application:

.. zephyr-app-commands::
:zephyr-app: samples/drivers/led_ws2812
:board: <board>
:goals: flash
:compact:

When you connect to your board's serial console, you should see the
following output:

.. code-block:: none

***** Booting Zephyr OS build v2.1.0-rc1-191-gd2466cdaf045 *****
[00:00:00.005,920] <inf> main: Found LED strip device WS2812
[00:00:00.005,950] <inf> main: Displaying pattern on strip

References
**********

- `RGB LED strips: an overview <http://nut-bolt.nl/2012/rgb-led-strips/>`_
- `74AHCT125 datasheet
<https://cdn-shop.adafruit.com/datasheets/74AHC125.pdf>`_
- An excellent `blog post on WS2812 timing`_.