rt_thread studio串口问题

问题遇到的现象和发生背景

问题相关代码，请勿粘贴截图

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

rt_thread studio报错Unable to open connection: Unable to open serial port
代码如下：
#include <rtthread.h>
#include <board.h>
#include <rtdevice.h>

#define DBG_TAG "main"
#define DBG_LVL DBG_LOG
#include <rtdbg.h>

#define SAMPLE_UART_NAME "uart2"

static struct rt_semaphore rx_sem;
static rt_device_t serial;

static rt_err_t uart_input(rt_device_t dev, rt_size_t size)
{

rt_sem_release(&rx_sem);

return RT_EOK;

}

static void serial_thread_entry(void *parameter)
{
char ch;

while (1)
{

    while (rt_device_read(serial, -1, &ch, 1) != 1)
    {
      
        rt_sem_take(&rx_sem, RT_WAITING_FOREVER);
    }

    ch = ch;
    rt_device_write(serial, 0, &ch, 1);
}

}

static int uart_sample()
{
rt_err_t ret = RT_EOK;
char uart_name[RT_NAME_MAX];
char str[] = "hello RT-Thread!\r\n";

serial = rt_device_find(SAMPLE_UART_NAME);
if (!serial)
{
    rt_kprintf("find %s failed!\n", uart_name);
    return RT_ERROR;
}


rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);

rt_device_open(serial, RT_DEVICE_FLAG_INT_RX);

rt_device_set_rx_indicate(serial, uart_input);

rt_device_write(serial, 0, str, (sizeof(str) - 1));


rt_thread_t thread = rt_thread_create("serial", serial_thread_entry, RT_NULL, 1024, 25, 10);

if (thread != RT_NULL)
{
    rt_thread_startup(thread);
}
else
{
    ret = RT_ERROR;
}

return ret;

}

int main(void)
{
uart_sample();
return RT_EOK;
}

board.h中也添加了入下代码
#define BSP_USING_UART2
#define BSP_UART2_TX_PIN "PD5"
#define BSP_UART2_RX_PIN "PD6"

打开RTT上的串口助手 显示Unable to open connection: Unable to open serial port

想知道怎么解决