zephyr

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Gerard Marull-Paretas 79e6b0e0f6 includes: prefer <zephyr/kernel.h> over <zephyr/zephyr.h> As of today <zephyr/zephyr.h> is 100% equivalent to <zephyr/kernel.h>. This patch proposes to then include <zephyr/kernel.h> instead of <zephyr/zephyr.h> since it is more clear that you are including the Kernel APIs and (probably) nothing else. <zephyr/zephyr.h> sounds like a catch-all header that may be confusing. Most applications need to include a bunch of other things to compile, e.g. driver headers or subsystem headers like BT, logging, etc. The idea of a catch-all header in Zephyr is probably not feasible anyway. Reason is that Zephyr is not a library, like it could be for example `libpython`. Zephyr provides many utilities nowadays: a kernel, drivers, subsystems, etc and things will likely grow. A catch-all header would be massive, difficult to keep up-to-date. It is also likely that an application will only build a small subset. Note that subsystem-level headers may use a catch-all approach to make things easier, though. NOTE: This patch is NOT removing the header, just removing its usage in-tree. I'd advocate for its deprecation (add a #warning on it), but I understand many people will have concerns. Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>		2022-09-05 16:31:47 +02:00
..
boards	drivers: led: Remove unnecessary Kconfig settings	2022-08-11 17:46:43 +02:00
src	includes: prefer <zephyr/kernel.h> over <zephyr/zephyr.h>	2022-09-05 16:31:47 +02:00
CMakeLists.txt
prj.conf
README.rst	samples: basic: blinky_pwm: add support for espressif boards	2022-06-29 14:48:25 +00:00
sample.yaml

README.rst

.. _blink-led-sample:
.. _pwm-blinky-sample:

PWM Blinky
##########

Overview
********

This application blinks a LED using the :ref:`PWM API <pwm_api>`. See
:ref:`blinky-sample` for a GPIO-based sample.

The LED starts blinking at a 1 Hz frequency. The frequency doubles every 4
seconds until it reaches 128 Hz. The frequency will then be halved every 4
seconds until it returns to 1 Hz, completing a single blinking cycle. This
faster-then-slower blinking cycle then repeats forever.

Some PWM hardware cannot set the PWM period to 1 second to achieve the blinking
frequency of 1 Hz. This sample calibrates itself to what the hardware supports
at startup. The maximum PWM period is decreased appropriately until a value
supported by the hardware is found.

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

The board must have an LED connected to a PWM output channel. The PWM
controlling this LED must be configured using the ``pwm_led0`` :ref:`devicetree
<dt-guide>` alias, usually in the :ref:`BOARD.dts file
<devicetree-in-out-files>`.

Wiring
******

No additional wiring is necessary if ``pwm_led0`` refers to hardware that is
already connected to an LED on the board.

In these other cases, however, manual wiring is necessary:

.. list-table::
   :header-rows: 1

   * - Board
     - Wiring
   * - :ref:`nucleo_f401re_board`
     - connect PWM2 (PA0) to an LED
   * - :ref:`nucleo_l476rg_board`
     - connect PWM2 (PA0) to an LED
   * - :ref:`stm32f4_disco_board`
     - connect PWM2 (PA0) to an LED
   * - :ref:`nucleo_f302r8_board`
     - connect PWM2 (PA0) to an LED
   * - :ref:`nucleo_f103rb_board`
     - connect PWM1 (PA8) to an LED
   * - :ref:`nucleo_wb55rg_board`
     - connect PWM1 (PA8) to an LED
   * - :ref:`esp32`
     - connect GPIO2 to an LED
   * - :ref:`esp32s2_saola`
     - connect GPIO2 to an LED
   * - :ref:`esp32c3_devkitm`
     - connect GPIO2 to an LED

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

To build and flash this sample for the :ref:`nrf52840dk_nrf52840`:

.. zephyr-app-commands::
   :zephyr-app: samples/basic/blinky_pwm
   :board: nrf52840dk_nrf52840
   :goals: build flash
   :compact:

Change ``nrf52840dk_nrf52840`` appropriately for other supported boards.

After flashing, the sample starts blinking the LED as described above. It also
prints information to the board's console.