Zephyr+STM32F769 2초 주기로 깜박이는 LED 설치

Ubuntu 18.04 LTS
STM32F769 Discovery Kit (以下、STM32F769)
Zephyr 2.1.0-rc1

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/*
Nov.20, 2019 change to timer driven 
    - use timer instead of k_sleep() in while()
    - branched from [blinky] project
*/

#include <zephyr.h>
#include <device.h>
#include <drivers/gpio.h>

#define LED_PORT    DT_ALIAS_LED0_GPIOS_CONTROLLER
#define LED     DT_ALIAS_LED0_GPIOS_PIN

struct device *dev;

struct k_timer my_timer;
void my_expiry_function(struct k_timer *timer_id)
{
    static u32_t cnt = 0;

    gpio_pin_write(dev, LED, cnt % 2);
    cnt++;
}

void main(void)
{
    dev = device_get_binding(LED_PORT);
    gpio_pin_configure(dev, LED, GPIO_DIR_OUT);

    k_timer_init(&my_timer, my_expiry_function, NULL);
    k_timer_start(&my_timer, K_SECONDS(1), K_SECONDS(1)); // first duration=1s, interval=1s

    while (1) {
        //
    }
}