#打卡不停更#【FFH】OpenHarmony设备开发（五）-超声波传感器 原创 精华

static_library("WIFI_car_demo") {
    sources = [
        "WIFI_car.c",
        "WIFI_hcsr04.c",
    ]

    include_dirs = [
        "//utils/native/lite/include",
        "//kernel/liteos_m/components/cmsis/2.0",
        "//base/iot_hardware/peripheral/interfaces/kits",
        "//ohos_bundles/@ohos/device_soc_hisilicon/hi3861v100/sdk_liteos/include",
        "//ohos_bundles/@ohos/device_soc_hisilicon/hi3861v100/sdk_liteos/third_party/lwip_sack/include",

    ]
}
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#define GPIO_Trig 7
#define GPIO_Echo 8
int hcsr_gpio_init(void)
{

    IoTGpioInit(GPIO_Trig);
    hi_io_set_func(GPIO_Trig, 0);	//0是普通IO口的意思
    IoTGpioSetDir(GPIO_Trig, IOT_GPIO_DIR_OUT);

    IoTGpioInit(GPIO_Echo);
    hi_io_set_func(GPIO_Echo, 0);
    IoTGpioSetDir(GPIO_Echo, IOT_GPIO_DIR_IN);
}
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float GetDistance(void)
{
    IotGpioValue value = IOT_GPIO_VALUE0;
    float distance = 0.0;
    int flag = 0;
    static unsigned long start_time = 0, time = 0;
//发送声波
    IoTGpioSetOutputVal(GPIO_Trig, IOT_GPIO_VALUE1);
    hi_udelay(20);
    IoTGpioSetOutputVal(GPIO_Trig, IOT_GPIO_VALUE0);

    while (1)
    {//不断检测声波
        IoTGpioGetInputVal(GPIO_Echo, &value);
        //记录下高电平持续时间
        if (value == IOT_GPIO_VALUE1 && flag == 0)
        {
            start_time = hi_get_us();
            flag = 1;
        }
        if (value == IOT_GPIO_VALUE0 && flag == 1)
        {
            time = hi_get_us() - start_time;
            start_time = 0;
            break;
        }
    }
    distance = time * 0.034 / 2;
    printf("distance is %f\r\n", distance);
    return distance;
}
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void hcsr04_avoid(void)
{
    float distance = 0;
    //io口初始化
    hcsr_gpio_init();
    while (1)
    {
        //获取距离信息
        distance=GetDistance();
        if (distance < 20)
        {
            printf("Distance <20!!!");
            sem_d = 1;
            car_stop();
            car_backward();
            sleep(1);
            car_stop();
            sem_d = 0;            
        }
    }
}

void hcsr04_demo(void)
{
    osThreadAttr_t attr;

    attr.name = "hcsr04_Task";
    attr.attr_bits = 0U;
    attr.cb_mem = NULL;
    attr.cb_size = 0U;
    attr.stack_mem = NULL;
    attr.stack_size = 4096;
    attr.priority = 24;

    if (osThreadNew((osThreadFunc_t)hcsr04_avoid, NULL, &attr) == NULL)
    {
        printf("[hcsr04_Task] Falied to create hcsr04_Task!\n");
    }
}
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extern void hcsr04_demo(void);
hcsr04_demo();
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int sem_d=0;
while(1)
{
    if(sem_d==1)
    {
        continue;
    }
    //遥控小车代码...
}
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#ifndef __WIFI_CAR__
#define __WIFI_CAR__

void car_stop(void);
void car_backwward(void);
extern int sem_d;

#endif
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	float distance_sum[5];
    float distance = 0;
	//获取数据
    for (int i = 0; i < 5; i++)
    {
        distance_sum[i] = GetDistance();
    }
    int max_id = 0;
    int min_id = 0;
    //记录最大最小的数组下标
    for (int i = 1; i < 5; i++)
    {
        if (distance_sum[i] > distance_sum[max_id])
        {
            max_id = i;
        }
        if (distance_sum[i] < distance_sum[min_id])
        {
            min_id = i;
        }
    }
    for (int i = 0; i < 5; i++)
    {
        if (i != max_id && i != min_id)
        {
            distance += distance_sum[i];
        }
    }
    distance /= 3.0;
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