zephyr

History

Manuel Argüelles 5d2670ac1f drivers: pwm: mcux_ftm: allow to select clock source FTM internal counter can be clocked by one of three clock sources independent of the module bus clock. This patch introduces a DT property to perform the clock selection from DT. DT sources are updated to keep the current clock selection for all boards, with exception of ucans32k1sic board which is migrated to use system clock by default, as this seems to be a better choice for most cases. Some PWM LED samples require slower clock so overlays are added for those cases. Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>		2024-04-19 10:08:53 +02:00
..
boards	drivers: pwm: mcux_ftm: allow to select clock source	2024-04-19 10:08:53 +02:00
src	drivers: pwm: use pwm_is_ready_dt helper function	2023-08-30 10:19:47 +02:00
CMakeLists.txt	samples: blinky_pwm: fix missing project renaming	2022-10-31 09:22:59 -05:00
prj.conf	logging: Revamp menuconfig	2021-01-26 06:15:42 -05:00
README.rst	hwmv2: Introduce Hardware model version 2 and convert devices	2024-03-02 16:56:33 -05:00
sample.yaml	Revert "sample: basic: blinky_pwm: Exclude rpi_pico w variant"	2024-04-09 23:35:54 +02:00

README.rst

.. zephyr:code-sample:: pwm-blinky
   :name: PWM Blinky
   :relevant-api: pwm_interface

   Blink an LED using the PWM API.

Overview
********

This application blinks an LED using the :ref:`PWM API <pwm_api>`. See
:zephyr:code-sample:`blinky` 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_devkitc_wroom`
     - 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.