zephyr

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Keith Packard 0b90fd5adf samples, tests, boards: Switch main return type from void to int As both C and C++ standards require applications running under an OS to return 'int', adapt that for Zephyr to align with those standard. This also eliminates errors when building with clang when not using -ffreestanding, and reduces the need for compiler flags to silence warnings for both clang and gcc. Most of these changes were automated using coccinelle with the following script: @@ @@ - void + int main(...) { ... - return; + return 0; ... } Approximately 40 files had to be edited by hand as coccinelle was unable to fix them. Signed-off-by: Keith Packard <keithp@keithp.com>		2023-04-14 07:49:41 +09:00
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boards	…
src	…
CMakeLists.txt	…
README.rst	…
prj.conf	…
sample.yaml	…

README.rst

.. _fade-led-sample:

Fade LED
########

Overview
********

This application "fades" a LED using the :ref:`PWM API <pwm_api>`.

The LED starts off increases its brightness until it is fully or nearly fully
on. The brightness then decreases until the LED is off, completing on fade
cycle. Each cycle takes 2.5 seconds, and the cycles repeat forever. The PWM
period is taken from Devicetree. It should be fast enough to be above the
flicker fusion threshold.

Requirements and Wiring
***********************

This sample has the same requirements and wiring considerations as the
:ref:`pwm-blinky-sample`.

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

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

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

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

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