我有一个需要连接到 nRF52840DK board 的北欧 LSM6DSL accelerometer。我正在使用 Zephyr 实时操作系统，来自 Zephyr 的示例代码如下所示：

/*
 * Copyright (c) 2018 STmicroelectronics
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr.h>
#include <device.h>
#include <drivers/sensor.h>
#include <stdio.h>
#include <sys/util.h>

static inline float out_ev(struct sensor_value *val)
{
    return (val->val1 + (float)val->val2 / 1000000);
}

static int print_samples;
static int lsm6dsl_trig_cnt;

static struct sensor_value accel_x_out,accel_y_out,accel_z_out;
static struct sensor_value gyro_x_out,gyro_y_out,gyro_z_out;
#if defined(CONFIG_LSM6DSL_EXT0_LIS2MDL)
static struct sensor_value magn_x_out,magn_y_out,magn_z_out;
#endif
#if defined(CONFIG_LSM6DSL_EXT0_LPS22HB)
static struct sensor_value press_out,temp_out;
#endif

#ifdef CONFIG_LSM6DSL_TRIGGER
static void lsm6dsl_trigger_handler(const struct device *dev,struct sensor_trigger *trig)
{
    static struct sensor_value accel_x,accel_y,accel_z;
    static struct sensor_value gyro_x,gyro_y,gyro_z;
#if defined(CONFIG_LSM6DSL_EXT0_LIS2MDL)
    static struct sensor_value magn_x,magn_y,magn_z;
#endif
#if defined(CONFIG_LSM6DSL_EXT0_LPS22HB)
    static struct sensor_value press,temp;
#endif
    lsm6dsl_trig_cnt++;

    sensor_sample_fetch_chan(dev,SENSOR_CHAN_accEL_XYZ);
    sensor_channel_get(dev,SENSOR_CHAN_accEL_X,&accel_x);
    sensor_channel_get(dev,SENSOR_CHAN_accEL_Y,&accel_y);
    sensor_channel_get(dev,SENSOR_CHAN_accEL_Z,&accel_z);

    /* lsm6dsl gyro */
    sensor_sample_fetch_chan(dev,SENSOR_CHAN_GYRO_XYZ);
    sensor_channel_get(dev,SENSOR_CHAN_GYRO_X,&gyro_x);
    sensor_channel_get(dev,SENSOR_CHAN_GYRO_Y,&gyro_y);
    sensor_channel_get(dev,SENSOR_CHAN_GYRO_Z,&gyro_z);

#if defined(CONFIG_LSM6DSL_EXT0_LIS2MDL)
    /* lsm6dsl external magn */
    sensor_sample_fetch_chan(dev,SENSOR_CHAN_MAGN_XYZ);
    sensor_channel_get(dev,SENSOR_CHAN_MAGN_X,&magn_x);
    sensor_channel_get(dev,SENSOR_CHAN_MAGN_Y,&magn_y);
    sensor_channel_get(dev,SENSOR_CHAN_MAGN_Z,&magn_z);
#endif

#if defined(CONFIG_LSM6DSL_EXT0_LPS22HB)
    /* lsm6dsl external press/temp */
    sensor_sample_fetch_chan(dev,SENSOR_CHAN_PRESS);
    sensor_channel_get(dev,SENSOR_CHAN_PRESS,&press);

    sensor_sample_fetch_chan(dev,SENSOR_CHAN_AMBIENT_TEMP);
    sensor_channel_get(dev,SENSOR_CHAN_AMBIENT_TEMP,&temp);
#endif

    if (print_samples) {
        print_samples = 0;

        accel_x_out = accel_x;
        accel_y_out = accel_y;
        accel_z_out = accel_z;

        gyro_x_out = gyro_x;
        gyro_y_out = gyro_y;
        gyro_z_out = gyro_z;

#if defined(CONFIG_LSM6DSL_EXT0_LIS2MDL)
        magn_x_out = magn_x;
        magn_y_out = magn_y;
        magn_z_out = magn_z;
#endif

#if defined(CONFIG_LSM6DSL_EXT0_LPS22HB)
        press_out = press;
        temp_out = temp;
#endif
    }

}
#endif

void main(void)
{
    int cnt = 0;
    char out_str[64];
    struct sensor_value odr_attr;
    const struct device *lsm6dsl_dev = device_get_binding(DT_LABEL(DT_INST(0,st_lsm6dsl)));

    if (lsm6dsl_dev == NULL) {
        printk("Could not get LSM6DSL device\n");
        return;
    }

    /* set accel/gyro sampling frequency to 104 Hz */
    odr_attr.val1 = 104;
    odr_attr.val2 = 0;

    if (sensor_attr_set(lsm6dsl_dev,SENSOR_CHAN_accEL_XYZ,SENSOR_ATTR_SAMPLING_FREQUENCY,&odr_attr) < 0) {
        printk("Cannot set sampling frequency for accelerometer.\n");
        return;
    }

    if (sensor_attr_set(lsm6dsl_dev,SENSOR_CHAN_GYRO_XYZ,&odr_attr) < 0) {
        printk("Cannot set sampling frequency for gyro.\n");
        return;
    }

#ifdef CONFIG_LSM6DSL_TRIGGER
    struct sensor_trigger trig;

    trig.type = SENSOR_TRIG_DATA_READY;
    trig.chan = SENSOR_CHAN_accEL_XYZ;

    if (sensor_trigger_set(lsm6dsl_dev,&trig,lsm6dsl_trigger_handler) != 0) {
        printk("Could not set sensor type and channel\n");
        return;
    }
#endif

    if (sensor_sample_fetch(lsm6dsl_dev) < 0) {
        printk("Sensor sample update error\n");
        return;
    }

    while (1) {
        /* Erase previous */
        printk("\0033\014");
        printf("LSM6DSL sensor samples:\n\n");

        /* lsm6dsl accel */
        sprintf(out_str,"accel x:%f ms/2 y:%f ms/2 z:%f ms/2",out_ev(&accel_x_out),out_ev(&accel_y_out),out_ev(&accel_z_out));
        printk("%s\n",out_str);

        /* lsm6dsl gyro */
        sprintf(out_str,"gyro x:%f dps y:%f dps z:%f dps",out_ev(&gyro_x_out),out_ev(&gyro_y_out),out_ev(&gyro_z_out));
        printk("%s\n",out_str);

#if defined(CONFIG_LSM6DSL_EXT0_LIS2MDL)
        /* lsm6dsl external magn */
        sprintf(out_str,"magn x:%f gauss y:%f gauss z:%f gauss",out_ev(&magn_x_out),out_ev(&magn_y_out),out_ev(&magn_z_out));
        printk("%s\n",out_str);
#endif

#if defined(CONFIG_LSM6DSL_EXT0_LPS22HB)
        /* lsm6dsl external press/temp */
        sprintf(out_str,"press: %f kPa - temp: %f deg",out_ev(&press_out),out_ev(&temp_out));
        printk("%s\n",out_str);
#endif

        printk("loop:%d trig_cnt:%d\n\n",++cnt,lsm6dsl_trig_cnt);

        print_samples = 1;
        k_sleep(K_MSEC(2000));
    }
}

根据我之前使用 Arduino 的经验，您需要在 main 函数之前定义引脚，但在此代码示例中没有关于引脚的任何定义。所以我的问题是：当连接到传感器时，电路板如何知道要使用哪些引脚？

提前致谢！