64 lines
1.9 KiB
ReStructuredText
64 lines
1.9 KiB
ReStructuredText
.. _rgb-led-sample:
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PWM: RGB LED
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############
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Overview
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********
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This is a sample app which drives an RGB LED using PWM.
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There are three single-color component LEDs in an RGB LED. Each component LED
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is driven by a PWM port where the pulse width is changed from zero to the period
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indicated in Devicetree. Such period should be fast enough to be above the
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flicker fusion threshold (the minimum flicker rate where the LED is perceived as
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being steady). The sample causes each LED component to step from dark to max
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brightness. Three **for** loops (one for each component LED) generate a gradual
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range of color changes from the RGB LED, and the sample repeats forever.
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Requirements
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************
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The board must have red, green, and blue LEDs connected via PWM output channels.
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The LED PWM channels must be configured using the following :ref:`devicetree
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<dt-guide>` aliases, usually in the :ref:`BOARD.dts file
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<devicetree-in-out-files>`:
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- ``red-pwm-led``
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- ``green-pwm-led``
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- ``blue-pwm-led``
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You will see at least one of these errors if you try to build this sample for
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an unsupported board:
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.. code-block:: none
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Unsupported board: red-pwm-led devicetree alias is not defined
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Unsupported board: green-pwm-led devicetree alias is not defined
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Unsupported board: blue-pwm-led devicetree alias is not defined
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See :zephyr_file:`boards/arm/hexiwear_k64/hexiwear_k64.dts` for an example
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:file:`BOARD.dts` file which supports this sample.
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Wiring
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******
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No additional wiring is necessary if the required devicetree aliases refer to
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hardware that is already connected to LEDs on the board.
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Otherwise, LEDs should be connected to the appropriate PWM channels.
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Building and Running
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********************
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For example, to build and flash this board for :ref:`hexiwear_k64`:
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.. zephyr-app-commands::
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:zephyr-app: samples/basic/rgb_led
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:board: hexiwear_k64
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:goals: build flash
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:compact:
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Change ``hexiwear_k64`` appropriately for other supported boards.
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