text: /**
   * Copyright (c) 2015 - 2017, Nordic Semiconductor ASA
   * 
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
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   *    list of conditions and the following disclaimer.
   * 
   * 2. Redistributions in binary form, except as embedded into a Nordic
   *    Semiconductor ASA integrated circuit in a product or a software update for
   *    such product, must reproduce the above copyright notice, this list of
   *    conditions and the following disclaimer in the documentation and/or other
   *    materials provided with the distribution.
   * 
   * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
   *    contributors may be used to endorse or promote products derived from this
   *    software without specific prior written permission.
   * 
   * 4. This software, with or without modification, must only be used with a
   *    Nordic Semiconductor ASA integrated circuit.
   * 
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   *    engineered, decompiled, modified and/or disassembled.
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   */
  /** @file
   * @defgroup pwm_example_main main.c
   * @{
   * @ingroup pwm_example
   *
   * @brief  PWM Example Application main file.
   *
   * This file contains the source code for a sample application using PWM.
   *
   *
   */
  
  #include <stdbool.h>
  #include <stdint.h>
  #include "nrf.h"
  #include "app_error.h"
  #include "bsp.h"
  #include "nrf_delay.h"
  #include "app_pwm.h"
  
  APP_PWM_INSTANCE(PWM1,1);                   // Create the instance "PWM1" using TIMER1.
  
  static volatile bool ready_flag;            // A flag indicating PWM status.
  
  void pwm_ready_callback(uint32_t pwm_id)    // PWM callback function
  {
      ready_flag = true;
  }
  
  int main(void)
  {
      ret_code_t err_code;
  
      /* 2-channel PWM, 200Hz, output on DK LED pins. */
      app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_2CH(5000L, BSP_LED_0, BSP_LED_1);
  
      /* Switch the polarity of the second channel. */
      pwm1_cfg.pin_polarity[1] = APP_PWM_POLARITY_ACTIVE_HIGH;
  
      /* Initialize and enable PWM. */
      err_code = app_pwm_init(&PWM1,&pwm1_cfg,pwm_ready_callback);
      APP_ERROR_CHECK(err_code);
      app_pwm_enable(&PWM1);
  
      uint32_t value;
      while (true)
      {
          for (uint8_t i = 0; i < 40; ++i)
          {
              value = (i < 20) ? (i * 5) : (100 - (i - 20) * 5);
  
              ready_flag = false;
              /* Set the duty cycle - keep trying until PWM is ready... */
              while (app_pwm_channel_duty_set(&PWM1, 0, value) == NRF_ERROR_BUSY);
  
              /* ... or wait for callback. */
              while (!ready_flag);
              APP_ERROR_CHECK(app_pwm_channel_duty_set(&PWM1, 1, value));
              nrf_delay_ms(25);
          }
      }
  
  }
  
  
  /** @} */
  