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samples: peripheral: add PWM sample
Add sample to show the use of PWM. Co-authored-by: Bartosz Gentkowski <[email protected]> Signed-off-by: Eivind Jølsgard <[email protected]>
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‎doc/nrf-bm/release_notes/release_notes_changelog.rst‎

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Peripheral samples
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------------------
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No changes since the latest nRF Connect SDK Bare Metal release.
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* Added the :ref:`pwm_sample` sample.
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DFU samples
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-----------

‎samples/peripherals/pwm/CMakeLists.txt‎

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#
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# Copyright (c) 2025 Nordic Semiconductor ASA
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#
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# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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#
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cmake_minimum_required(VERSION 3.20.0)
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find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
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project(pwm)
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target_sources(app PRIVATE src/main.c)

‎samples/peripherals/pwm/Kconfig‎

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#
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# Copyright (c) 2025 Nordic Semiconductor ASA
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#
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# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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#
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menu "PWM sample"
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config PWM_IRQ_PRIO
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int "PWM IRQ priority"
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default 5
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config PWM_PLAYBACK_COUNT
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int "PWM playback count"
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default 1
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help
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Number of times the sequence will be replayed until the
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NRFX_PWM_EVT_FINISHED event is raised.
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config PWM_VALUE_REPEATS
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int "PWM value repeats"
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default 150
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help
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Number of times that each duty cycle is to be repeated (after being played once).
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module=PWM_SAMPLE
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module-str=PWM Sample
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source "$(ZEPHYR_BASE)/subsys/logging/Kconfig.template.log_config"
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endmenu # "PWM sample"
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source "Kconfig.zephyr"

‎samples/peripherals/pwm/README.rst‎

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.. _pwm_sample:
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PWM
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###
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.. contents::
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:local:
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:depth: 2
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The PWM sample demonstrates how to configure and use Pulse Width Modulation (PWM) with |BMlong|.
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Requirements
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************
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The sample supports the following development kits:
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.. tabs::
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.. group-tab:: Simple board variants
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The following board variants do **not** have DFU capabilities.
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.. list-table::
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:header-rows: 1
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* - Hardware platform
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- PCA
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- SoftDevice
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- Board target
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* - `nRF54L15 DK`_
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- PCA10156
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- S115
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- bm_nrf54l15dk/nrf54l15/cpuapp/s115_softdevice
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* - `nRF54L15 DK`_ (emulating nRF54L10)
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- PCA10156
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- S115
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- bm_nrf54l15dk/nrf54l10/cpuapp/s115_softdevice
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* - `nRF54L15 DK`_ (emulating nRF54L05)
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- PCA10156
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- S115
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- bm_nrf54l15dk/nrf54l05/cpuapp/s115_softdevice
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.. group-tab:: MCUboot board variants
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The following board variants have DFU capabilities.
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.. list-table::
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:header-rows: 1
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* - Hardware platform
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- PCA
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- SoftDevice
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- Board target
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* - `nRF54L15 DK`_
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- PCA10156
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- S115
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- bm_nrf54l15dk/nrf54l15/cpuapp/s115_softdevice/mcuboot
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* - `nRF54L15 DK`_ (emulating nRF54L10)
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- PCA10156
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- S115
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- bm_nrf54l15dk/nrf54l10/cpuapp/s115_softdevice/mcuboot
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* - `nRF54L15 DK`_ (emulating nRF54L05)
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- PCA10156
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- S115
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- bm_nrf54l15dk/nrf54l05/cpuapp/s115_softdevice/mcuboot
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Overview
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********
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The sample initializes a PWM instance that blinks **LED 1** and **LED 3** on the device.
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.. note::
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The PWM signal can be exposed only on GPIO pins that belong to the same domain as the target pin.
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For the nRF54L Series, there is only one domain which contains both PWM and GPIO: PWM20/21/22 and GPIO Port P1.
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Therefore, for these devices, only LEDs connected to P1 can work with PWM - for the nRF54L15 DK these are **LED 1** and **LED 3**.
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Building and running
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********************
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This sample can be found under :file:`samples/peripherals/pwm/` in the |BMshort| folder structure.
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.. include:: /includes/create_sample.txt
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.. include:: /includes/configure_and_build_sample.txt
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.. include:: /includes/program_sample.txt
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Testing
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=======
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You can test this sample by performing the following steps:
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1. Compile and program the application.
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#. Observe that the ``PWM sample started`` message is printed.
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#. Observe that **LED 1** and **LED 3** are blinking.

‎samples/peripherals/pwm/prj.conf‎

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CONFIG_LOG=y
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CONFIG_LOG_BACKEND_BM_UARTE=y

‎samples/peripherals/pwm/sample.yaml‎

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sample:
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name: PWM Sample
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tests:
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sample.pwm:
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sysbuild: true
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build_only: true
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integration_platforms:
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- bm_nrf54l15dk/nrf54l05/cpuapp/s115_softdevice
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- bm_nrf54l15dk/nrf54l10/cpuapp/s115_softdevice
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- bm_nrf54l15dk/nrf54l15/cpuapp/s115_softdevice
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- bm_nrf54l15dk/nrf54l05/cpuapp/s115_softdevice/mcuboot
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- bm_nrf54l15dk/nrf54l10/cpuapp/s115_softdevice/mcuboot
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- bm_nrf54l15dk/nrf54l15/cpuapp/s115_softdevice/mcuboot
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platform_allow:
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- bm_nrf54l15dk/nrf54l05/cpuapp/s115_softdevice
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- bm_nrf54l15dk/nrf54l10/cpuapp/s115_softdevice
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- bm_nrf54l15dk/nrf54l15/cpuapp/s115_softdevice
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- bm_nrf54l15dk/nrf54l05/cpuapp/s115_softdevice/mcuboot
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- bm_nrf54l15dk/nrf54l10/cpuapp/s115_softdevice/mcuboot
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- bm_nrf54l15dk/nrf54l15/cpuapp/s115_softdevice/mcuboot
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tags: ci_build

‎samples/peripherals/pwm/src/main.c‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
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*/
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#include <zephyr/logging/log.h>
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#include <zephyr/logging/log_ctrl.h>
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#include <nrfx_pwm.h>
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#include <board-config.h>
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LOG_MODULE_REGISTER(app, CONFIG_PWM_SAMPLE_LOG_LEVEL);
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/* nrfx PWM instance index. */
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#define PWM_INST_IDX 20
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nrf_pwm_values_common_t pwm_val[] = {
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0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000,
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900, 800, 700, 600, 500, 400, 300, 200, 100, 0
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};
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static void pwm_handler(nrfx_pwm_evt_type_t event_type, void *ctx)
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{
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static uint32_t curr_loop = 1;
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LOG_INF("Loops: %u ", curr_loop);
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curr_loop++;
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}
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int main(void)
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{
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nrfx_err_t err;
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nrfx_pwm_t pwm_instance = NRFX_PWM_INSTANCE(PWM_INST_IDX);
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/*
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* PWM signal can be exposed on GPIO pin only within the same domain.
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* For nRF54L-series there is only one domain which contains both PWM and GPIO:
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* PWM20/21/22 and GPIO Port P1.
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* Only LEDs connected to P1 can work with PWM, in this case LED1 and LED3.
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*/
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nrfx_pwm_config_t config = NRFX_PWM_DEFAULT_CONFIG(BOARD_PIN_LED_1, BOARD_PIN_LED_3,
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NRF_PWM_PIN_NOT_CONNECTED,
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NRF_PWM_PIN_NOT_CONNECTED);
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nrf_pwm_sequence_t seq = {
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.values = {pwm_val},
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.length = NRFX_ARRAY_SIZE(pwm_val),
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.repeats = CONFIG_PWM_VALUE_REPEATS,
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.end_delay = 0
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};
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LOG_INF("PWM sample started");
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IRQ_CONNECT(NRFX_IRQ_NUMBER_GET(NRF_PWM_INST_GET(PWM_INST_IDX)),
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CONFIG_PWM_IRQ_PRIO, NRFX_PWM_INST_HANDLER_GET(20), 0, 0);
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err = nrfx_pwm_init(&pwm_instance, &config, pwm_handler, &pwm_instance);
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if (err != NRFX_SUCCESS) {
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LOG_ERR("Failed to initialize PWM, nrfx_error %#x", err);
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goto idle;
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}
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nrfx_pwm_simple_playback(&pwm_instance, &seq, CONFIG_PWM_PLAYBACK_COUNT,
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NRFX_PWM_FLAG_LOOP);
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idle:
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while (true) {
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while (LOG_PROCESS()) {
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}
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/* Wait for an event. */
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__WFE();
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/* Clear Event Register */
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__SEV();
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__WFE();
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}
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return 0;
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}

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