text: /*
   * Copyright (c) 2016 Intel Corporation
   *
   * SPDX-License-Identifier: Apache-2.0
   */
  
  /**
   * @file Sample app to demonstrate PWM.
   *
   * This app uses PWM[0].
   */
  
  #include <zephyr.h>
  #include <misc/printk.h>
  #include <device.h>
  #include <pwm.h>
  
  #if defined(CONFIG_SOC_STM32F401XE) || defined(CONFIG_SOC_STM32F412ZG) || \
  	defined(CONFIG_SOC_STM32F413XX) || defined(CONFIG_SOC_STM32L476XG) || \
  	defined(CONFIG_SOC_STM32F407XG) || defined(CONFIG_SOC_STM32F302X8)
  #define PWM_DRIVER DT_PWM_STM32_2_DEV_NAME
  #define PWM_CHANNEL 1
  #elif CONFIG_SOC_STM32F103XB
  #define PWM_DRIVER DT_PWM_STM32_1_DEV_NAME
  #define PWM_CHANNEL 1
  #elif defined(CONFIG_SOC_QUARK_SE_C1000) || defined(CONFIG_SOC_QUARK_D2000)
  #define PWM_DRIVER CONFIG_PWM_QMSI_DEV_NAME
  #define PWM_CHANNEL 0
  #elif defined(CONFIG_SOC_FAMILY_NRF)
  #define PWM_DRIVER CONFIG_PWM_NRF5_SW_0_DEV_NAME
  #define PWM_CHANNEL LED0_GPIO_PIN
  #elif defined(CONFIG_BOARD_COLIBRI_IMX7D_M4)
  #define PWM_DRIVER	PWM_1_LABEL
  #define PWM_CHANNEL	0
  #elif defined(CONFIG_SOC_FAMILY_NRF)
  #define PWM_DRIVER	CONFIG_PWM_NRF5_SW_0_DEV_NAME
  #define PWM_CHANNEL	LED0_GPIO_PIN
  #elif defined(PWM_LED0_PWM_CONTROLLER) && defined(PWM_LED0_PWM_CHANNEL)
  /* get the defines from dt (based on alias 'pwm-led0') */
  #define PWM_DRIVER	PWM_LED0_PWM_CONTROLLER
  #define PWM_CHANNEL	PWM_LED0_PWM_CHANNEL
  #else
  #error "Choose supported PWM driver"
  #endif
  
  /* in micro second */
  #define MIN_PERIOD	(USEC_PER_SEC / 64)
  
  /* in micro second */
  #define MAX_PERIOD	USEC_PER_SEC
  
  void main(void)
  {
  	struct device *pwm_dev;
  	u32_t period = MAX_PERIOD;
  	u8_t dir = 0;
  
  	printk("PWM demo app-blink LED\n");
  
  	pwm_dev = device_get_binding(PWM_DRIVER);
  	if (!pwm_dev) {
  		printk("Cannot find %s!\n", PWM_DRIVER);
  		return;
  	}
  
  	while (1) {
  		if (pwm_pin_set_usec(pwm_dev, PWM_CHANNEL,
  				     period, period / 2)) {
  			printk("pwm pin set fails\n");
  			return;
  		}
  
  		if (dir) {
  			period *= 2;
  
  			if (period > MAX_PERIOD) {
  				dir = 0;
  				period = MAX_PERIOD;
  			}
  		} else {
  			period /= 2;
  
  			if (period < MIN_PERIOD) {
  				dir = 1;
  				period = MIN_PERIOD;
  			}
  		}
  
  		k_sleep(MSEC_PER_SEC * 4);
  	}
  }
  