在xpt2046驱动程序中遇到离奇的事情，真的很离奇

发布于 2024-04-13 10:38:23 浏览：297 订阅该版

[tocm]

```c
void xpt2046_calibration(void)
{
    /* Find the TFT LCD device */
    const char* lcd_name = "lcd";
    const char* touch_name = "xpt0";

#    *** const rt_uint32_t white = 0xFFFFFFFF;***

rt_device_t lcd = rt_device_find(lcd_name);
    if (lcd == RT_NULL)
    {
        LOG_E(LOG_TAG" cannot find lcd device named %s\n", lcd_name);
        return;
    }
    if (rt_device_open(lcd, RT_DEVICE_OFLAG_RDWR) != RT_EOK)
    {
        LOG_E(LOG_TAG" cannot open lcd device named %s\n", lcd_name);
        return;
    }

rt_xpt2046_t touch = (rt_xpt2046_t)rt_device_find(touch_name);
    if (touch == RT_NULL)
    {
        LOG_E(LOG_TAG" cannot find touch device named %s\n", touch_name);
        return;
    }
    if (rt_device_open(touch, RT_DEVICE_FLAG_INT_RX) != RT_EOK)
    {
        LOG_E(LOG_TAG" cannot open touch device named %s\n", touch_name);
        return;
    }
    struct rt_device_graphic_info lcd_info;
    rt_device_control(lcd, RTGRAPHIC_CTRL_GET_INFO, &lcd_info);
   * **const uint32_t black = 0x0000;***

for (rt_uint32_t y = 0; y < lcd_info.height; ++y)
    {

rt_graphix_ops(lcd)->draw_hline((const char *)(&black), 0, lcd_info.width, y);
    }
    rt_uint32_t cross_size = (lcd_info.width > lcd_info.height ? lcd_info.height : lcd_info.width) / 10;
    rt_uint32_t x0 = cross_size;
    rt_uint32_t y0 = cross_size;
    rt_uint32_t x1 = lcd_info.width - cross_size;
    rt_uint32_t y1 = cross_size;
    rt_uint32_t x2 = lcd_info.width - cross_size;
    rt_uint32_t y2 = lcd_info.height - cross_size;
    rt_uint32_t x3 = cross_size;
    rt_uint32_t y3 = lcd_info.height - cross_size;

// Upper left cross

rt_graphix_ops(lcd)->draw_hline((const char *)(&white), 0, x0+cross_size, y0);
    rt_graphix_ops(lcd)->draw_vline((const char *)(&white), x0, 0, y0+cross_size);
    lcd_show_string(50,50,16,"Touch screen calibration");
    touch->min_raw_x = 0;
    touch->min_raw_y = 0;
    touch->max_raw_x = 4096;
    touch->max_raw_y = 4096;
    touch->parent.info.range_x = 4096;
    touch->parent.info.range_y = 4096;

rt_uint16_t x_raw[4];
    rt_uint16_t y_raw[4];
    rt_uint8_t raw_idx = 0;
    rt_memset(&x_raw, 0, sizeof(rt_uint32_t)*4);
    rt_memset(&y_raw, 0, sizeof(rt_uint32_t)*4);
    while (1)
    {     const uint32_t black = 0x0000;
        struct rt_touch_data read_data;
        rt_memset(&read_data, 0, sizeof(struct rt_touch_data));
        if (rt_device_read(touch, 0, &read_data, 1) == 1)
        {
            x_raw[raw_idx] = read_data.x_coordinate;
            y_raw[raw_idx++] = read_data.y_coordinate;
            LOG_I(LOG_TAG" %d point capture", raw_idx-1);
            for (rt_uint32_t y = 0; y < lcd_info.height; ++y)
            {

rt_graphix_ops(lcd)->draw_hline((const char *)(&black), 0, lcd_info.width, y);
            }
            rt_thread_mdelay(1000);
            if (raw_idx >= 4)
            {
                break;
            }

switch(raw_idx)
            {
                case 1:
                    // Upper right cross
                    rt_graphix_ops(lcd)->draw_hline((const char *)(&white), x1-cross_size, lcd_info.width, y1);
                    rt_graphix_ops(lcd)->draw_vline((const char *)(&white), x1, 0, y1+cross_size);
                    rt_thread_mdelay(1000);
                    break;
                case 2:
                    // lower right cross
                    rt_graphix_ops(lcd)->draw_hline((const char *)(&white), x2-cross_size, lcd_info.width, y2);
                    rt_graphix_ops(lcd)->draw_vline((const char *)(&white), x2, y2-cross_size, lcd_info.height);
                    rt_thread_mdelay(1000);
                    break;
                case 3:
                    // lower left cross
                    rt_graphix_ops(lcd)->draw_hline((const char *)(&white), 0, x3+cross_size, y3);
                    rt_graphix_ops(lcd)->draw_vline((const char *)(&white), x3, y3-cross_size, lcd_info.height);
                    rt_thread_mdelay(1000);
                    break;
                default:
                    break;
            }
        }
        rt_thread_mdelay(10);
    }
    rt_uint32_t min_x = (x_raw[0]+x_raw[3])/2;
    rt_uint32_t max_x = (x_raw[1]+x_raw[2])/2;
    rt_uint32_t min_y = (y_raw[0]+y_raw[1])/2;
    rt_uint32_t max_y = (y_raw[2]+y_raw[3])/2;

rt_uint32_t x_raw_cnt_per_pixel = (max_x-min_x) / (x1-x0);
    rt_uint32_t y_raw_cnt_per_pixel = (max_y-min_y) / (y2-y1);

min_x -= cross_size * x_raw_cnt_per_pixel;
    max_x += cross_size * x_raw_cnt_per_pixel;
    min_y -= cross_size * y_raw_cnt_per_pixel;
    max_y += cross_size * y_raw_cnt_per_pixel;

touch->min_raw_x = min_x;
    touch->min_raw_y = min_y;
    touch->max_raw_x = max_x;
    touch->max_raw_y = max_y;
    touch->parent.info.range_x = lcd_info.width;
    touch->parent.info.range_y = lcd_info.height;

LOG_I(LOG_TAG" Calibration result, min_x:%d\n, min_y:%d\n, max_x:%d\n, max_y:%d\n", min_x, min_y, max_x, max_y);
    rt_thread_mdelay(1000);

rt_device_close(lcd);
    rt_device_close(touch);
}
MSH_CMD_EXPORT(xpt2046_calibration, xpt2046 calibration)
```

![screenshot_1712982094830.png](https://oss-club.rt-thread.org/uploads/20240413/728df7dda108096e5f35eb6d8926e39d.png.webp)

为什么我这个程序的第8行和第36行这两个量
```
“const rt_uint32_t white = 0xFFFFFFFF， const uint32_t black = 0x0000”;
```
不能都定义在开头，必须有一个要被定义在被使用的地方？
而且不管定义在那里编译都能通过，就是在单片机上执行程序会出问题。.