zephyr

History

Torsten Rasmussen 407b49b35c cmake: use find_package to locate Zephyr Using find_package to locate Zephyr. Old behavior was to use $ENV{ZEPHYR_BASE} for inclusion of boiler plate code. Whenever an automatic run of CMake happend by the build system / IDE then it was required that ZEPHYR_BASE was defined. Using ZEPHYR_BASE only to locate the Zephyr package allows CMake to cache the base variable and thus allowing subsequent invocation even if ZEPHYR_BASE is not set in the environment. It also removes the risk of strange build results if a user switchs between different Zephyr based project folders and forgetting to reset ZEPHYR_BASE before running ninja / make. Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>		2020-03-27 16:23:46 +01:00
..
boards	…
src	…
CMakeLists.txt	cmake: use find_package to locate Zephyr	2020-03-27 16:23:46 +01:00
README.rst	…
prj.conf	…
sample.yaml	…

README.rst

.. _led_lpd8806_sample:

LPD880x Sample Application
##########################

Overview
********

This sample application demonstrates basic usage of the lpd880x LED
strip driver, for controlling LED strips using LPD8803, LPD8806, and
compatible driver chips.

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

.. _these strips from AdaFruit: https://www.adafruit.com/product/306
.. _74AHCT125: https://cdn-shop.adafruit.com/datasheets/74AHC125.pdf

- LED strip using LPD8806 or compatible, such as `these strips from AdaFruit`_.

- Zephyr board with SPI master driver. SPI communications must use 5V
  signaling, which may require a level translator, such as the
  `74AHCT125`_.

- 5V power supply.

Wiring
******

#. Ensure your Zephyr board, the 5V power supply, and the LED strip
   share a common ground.
#. Connect the MOSI pin of your board's SPI master to the data input
   pin of the first LPD8806 IC in the strip.
#. Connect the SCLK pin of your board's SPI master to the clock input
   pin of the first LPD8806 IC in the strip.
#. Connect the 5V power supply pin to the 5V input of the LED strip.

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

The sample application is located at ``samples/drivers/led_lpd8806/``
in the Zephyr source tree.

Before running the application, configure it as follows.

#. Configure your board's SPI master in a configuration file under
   ``boards/`` in the sample directory.

   To provide additional configuration for some particular board,
   create a ``boards/YOUR_BOARD_NAME.conf`` file in the application
   directory. It will be merged into the application configuration.

   In this file, you must ensure that the SPI peripheral you want to
   use for this demo is enabled, and that its name is "lpd8806_spi".
   See ``boards/96b_carbon.conf`` for an example, and refer to your
   board's configuration options to set up your desired SPI master.

#. Set the number of LEDs in your strip in the application sources.
   This is determined by the macro ``STRIP_NUM_LEDS`` in the file
   ``src/main.c``. The value in the file was chosen to work with one
   meter of the AdaFruit strip.

Then build and flash the application:

.. zephyr-app-commands::
   :zephyr-app: samples/drivers/led_lpd8806
   :board: <board>
   :goals: flash
   :compact:

Refer to your :ref:`board's documentation <boards>` for alternative
flash instructions if your board doesn't support the ``flash`` target.

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

.. code-block:: none

   ***** BOOTING ZEPHYR OS v1.9.99 *****
   [general] [INF] main: Found SPI device lpd8806_spi
   [general] [INF] main: Found LED strip device lpd880x_strip
   [general] [INF] main: Displaying pattern on strip

References
**********

- `LPD8806 datasheet <https://cdn-shop.adafruit.com/datasheets/lpd8806+english.pdf>`_
- `RGB LED strips: an overview <http://nut-bolt.nl/2012/rgb-led-strips/>`_
- `74AHCT125 datasheet <https://cdn-shop.adafruit.com/datasheets/74AHC125.pdf>`_