ESP32cam--获取图片通过串口传到上位机

系统管理员 2023-06-21 08:54 13阅读 0赞

Qt上位机源码下载地址：https://download.csdn.net/download/qq\_28877125/12029837

## ESP32cam：分辨率、格式 ##

[资料来源][Link 1]

1、可用的分辨率如下：

typedef enum { 
        FRAMESIZE_96x96,    // 96x96
        FRAMESIZE_QQVGA,    // 160x120
        FRAMESIZE_QQVGA2,   // 128x160
        FRAMESIZE_QCIF,     // 176x144
        FRAMESIZE_HQVGA,    // 240x176
        FRAMESIZE_240x240,  // 240x240
        FRAMESIZE_QVGA,     // 320x240
        FRAMESIZE_CIF,      // 400x296
        FRAMESIZE_VGA,      // 640x480
        FRAMESIZE_SVGA,     // 800x600
        FRAMESIZE_XGA,      // 1024x768
        FRAMESIZE_SXGA,     // 1280x1024
        FRAMESIZE_UXGA,     // 1600x1200
        FRAMESIZE_QXGA,     // 2048*1536
        FRAMESIZE_INVALID
    } framesize_t;

2、可用的格式如下：

typedef enum { 
        PIXFORMAT_RGB565,    // 2BPP/RGB565
        PIXFORMAT_YUV422,    // 2BPP/YUV422
        PIXFORMAT_GRAYSCALE, // 1BPP/GRAYSCALE
        PIXFORMAT_JPEG,      // JPEG/COMPRESSED
        PIXFORMAT_RGB888,    // 3BPP/RGB888
        PIXFORMAT_RAW,       // RAW
        PIXFORMAT_RGB444,    // 3BP2P/RGB444
        PIXFORMAT_RGB555,    // 3BP2P/RGB555
    } pixformat_t;

在这里选择JPEG的格式。

## JPEG格式图片的基本知识 ##

[资料来源一][Link 2]  
[资料来源二][Link 3]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]1、JPEG图片格式组成部分：

**SOI（文件头）**\+**APP0（图像识别信息）**\+ **DQT（定义量化表）**\+ **SOF0（图像基本信息）**\+ **DHT（定义Huffman表）** \+ DRI（定义重新开始间隔）+ **SOS（扫描行开始）**\+ **EOI（文件尾）**

**其中粗体部分是必须的**

2、简单介绍：  
 JPEG 文件的格式是分为一个一个的段来存储的，段的多少和长度并不是一定的。JPEG文件的每个段都一定包含两部分，一个是段的标识，它由两个字节构成：第一个字节是十六进制0xFF，第二个字节对于不同的段，这个值是不同的。紧接着的两个字节存放的是这个段的长度（除了前面的两个字节0xFF和0xXX，X表示不确定。他们是不算到段的长度中的）。注意：这个长度的表示方法是按照高位在前，低位在后的。

段标识（1Byte）+段类型（1Byte）+段长度（2Byte）+段内容（…）

*  段标识已经固定为：0xFF
 *  段类型就有很多种：

<table> 
 <thead> 
  <tr> 
   <th>名称</th> 
   <th>标记码</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td></td> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>SOI</td> 
   <td>D8</td> 
   <td>文件头</td> 
  </tr> 
  <tr> 
   <td>EOI</td> 
   <td>D9</td> 
   <td>文件尾</td> 
  </tr> 
  <tr> 
   <td>SOF0</td> 
   <td>C0</td> 
   <td>帧开始（标准 JPEG）</td> 
  </tr> 
  <tr> 
   <td>SOF1</td> 
   <td>C1</td> 
   <td>同上</td> 
  </tr> 
  <tr> 
   <td>DHT</td> 
   <td>C4</td> 
   <td>定义 Huffman 表（霍夫曼表）</td> 
  </tr> 
  <tr> 
   <td>SOS</td> 
   <td>DA</td> 
   <td>扫描行开始</td> 
  </tr> 
  <tr> 
   <td>DQT</td> 
   <td>DB</td> 
   <td>定义量化表</td> 
  </tr> 
  <tr> 
   <td>DRI</td> 
   <td>DD</td> 
   <td>定义重新开始间隔</td> 
  </tr> 
  <tr> 
   <td>APP0</td> 
   <td>E0</td> 
   <td>定义交换格式和图像识别信息</td> 
  </tr> 
  <tr> 
   <td>COM</td> 
   <td>FE</td> 
   <td>注释</td> 
  </tr> 
 </tbody> 
</table>

3、简单粗暴的来说：

*  **SOI** 开头两个字节：0xFFD8
 *  **EOI** 结尾两个字节：0xFFD9

## 上ESP32CAM代码 ##

#include "esp_camera.h"
    
    #define KEY_PIN 15
    
    #define PWDN_GPIO_NUM 32
    #define RESET_GPIO_NUM -1
    #define XCLK_GPIO_NUM 0
    #define SIOD_GPIO_NUM 26
    #define SIOC_GPIO_NUM 27
    
    #define Y9_GPIO_NUM 35
    #define Y8_GPIO_NUM 34
    #define Y7_GPIO_NUM 39
    #define Y6_GPIO_NUM 36
    #define Y5_GPIO_NUM 21
    #define Y4_GPIO_NUM 19
    #define Y3_GPIO_NUM 18
    #define Y2_GPIO_NUM 5
    #define VSYNC_GPIO_NUM 25
    #define HREF_GPIO_NUM 23
    #define PCLK_GPIO_NUM 22
    
    static camera_config_t camera_config = { 
      .pin_pwdn = PWDN_GPIO_NUM,
      .pin_reset = RESET_GPIO_NUM,
      .pin_xclk = XCLK_GPIO_NUM, 
      .pin_sscb_sda = SIOD_GPIO_NUM,  
      .pin_sscb_scl = SIOC_GPIO_NUM,
         
      .pin_d7 = Y9_GPIO_NUM,
      .pin_d6 = Y8_GPIO_NUM,
      .pin_d5 = Y7_GPIO_NUM, 
      .pin_d4 = Y6_GPIO_NUM,
      .pin_d3 = Y5_GPIO_NUM,
      .pin_d2 = Y4_GPIO_NUM,  
      .pin_d1 = Y3_GPIO_NUM,
      .pin_d0 = Y2_GPIO_NUM,
      .pin_vsync = VSYNC_GPIO_NUM,
      .pin_href = HREF_GPIO_NUM,
      .pin_pclk = PCLK_GPIO_NUM,
    
      .xclk_freq_hz = 20000000,
      .ledc_timer = LEDC_TIMER_0,
      .ledc_channel = LEDC_CHANNEL_0,
      
      .pixel_format = PIXFORMAT_JPEG,
      .frame_size = FRAMESIZE_UXGA,
      .jpeg_quality = 12,
      .fb_count = 1,
    };
    
    esp_err_t camera_init(){ 
        //initialize the camera
        esp_err_t err = esp_camera_init(&camera_config);
        if (err != ESP_OK) { 
            Serial.print("Camera Init Failed");
            return err;
        }
        sensor_t * s = esp_camera_sensor_get();
        //initial sensors are flipped vertically and colors are a bit saturated
        if (s->id.PID == OV2640_PID) { 
            s->set_vflip(s, 1);//flip it back
            s->set_brightness(s, 1);//up the blightness just a bit
            s->set_contrast(s, 1);
        }
      
        Serial.print("Camera Init OK");
        return ESP_OK;
    }
    
    void setup() { 
      Serial.begin(115200);
      
      camera_init();
      
      pinMode(KEY_PIN, INPUT_PULLUP); //设置按键管脚输入上拉模式
      
      Serial.print("sys is running!");
    }
    int buttonState = 0;
    int btnHold = 0;
    
    void loop() { 
      
         buttonState = digitalRead(KEY_PIN); //读取按键返回状态值
        if (buttonState == LOW && btnHold == 0) 
        {  // 若按键被按下
            delay(100); //等待跳过按键抖动的不稳定过程
            if (buttonState == LOW) // 若按键被按下
            {   
                //Serial.print("click\r\n");
                btnHold = 1;
    
              //acquire a frame
              camera_fb_t * fb = esp_camera_fb_get();
              if (!fb) { 
                  
              }
              //replace this with your own function
              //process_image(fb->width, fb->height, fb->format, fb->buf, fb->len);
              
              //Serial.printf("width:%d, height:%d, format:%d, len:%d\r\n", fb->width, fb->height, fb->format, fb->len);
    
              for(int i = 0; i < fb->len; i++)
              { 
                  Serial.write(fb->buf[i++]); // 发送到上位机
              }
              //return the frame buffer back to the driver for reuse
              esp_camera_fb_return(fb);
                
            }
        }
        if(buttonState == HIGH)
        { 
            btnHold = 0;
        }
    }

很无奈串口打印的十六进制数开始的字节是这样子的，根本就不符合JPEG格式！

FF FF 00 4A 49 00 01 00 00 00 FF 00 00 08 0B 08 0B 0B 0D 0E 
    1E 12 11 25 1C 1E 26 2D 26 29 36 3B 33 34 2A 52 41 4A 4E 2F 
    55 54 5A 4C 4A DB 43 0D 0E 10 23 14 4A 2A 4A 4A 4A 4A 4A 4A 
    4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A 4A FF 
    00 00 01 01 01 01 00 00 00 00 01 03 05 07 09 0B C4 B5 00 01 
    03 04 05 04 00 01 01 03 04 05 21 41 13 61 22 14 81 A1 23 B1 
    15 D1 24 62 82 0A 17 19 25 27 29 34 36 38 3A 44 46 48 4A 54 
    56 58 5A 64 66 68 6A 74 76 78 7A 84 86 88 8A 93 95 97 99 A2

最后发现是串口写数据的方式是错误的：

for(int i = 0; i < fb->len; i++)
        { 
            Serial.write(fb->buf[i++]); // 错误的方法
        }

正确的方法：

Serial.write(fb->buf, fb->len); // 正确的发送图片数据的方法

或者

for(int i = 0; i < fb->len; i++)
        { 
            Serial.write(fb->buf[i]); // 正确的方法
        }

修改之后就在数据的开头看到了喜闻乐见的 FF D8 (这是JPEG格式的开头）

FF D8 FF E0 00 10 4A 46 49 46 00 01 01 01 00 00 00 00 00 00 
    FF DB 00 43 00 0C 08 09 0B 09 08 0C 0B 0A 0B 0E 0D 0C 0E 12 
    1E 14 12 11 11 12 25 1A 1C 16 1E 2C 26 2E 2D 2B 26 2A 29 30

最后完整的代码

#include "esp_camera.h"
    
    #define KEY_PIN 15
    
    #define PWDN_GPIO_NUM 32
    #define RESET_GPIO_NUM -1
    #define XCLK_GPIO_NUM 0
    #define SIOD_GPIO_NUM 26
    #define SIOC_GPIO_NUM 27
    
    #define Y9_GPIO_NUM 35
    #define Y8_GPIO_NUM 34
    #define Y7_GPIO_NUM 39
    #define Y6_GPIO_NUM 36
    #define Y5_GPIO_NUM 21
    #define Y4_GPIO_NUM 19
    #define Y3_GPIO_NUM 18
    #define Y2_GPIO_NUM 5
    #define VSYNC_GPIO_NUM 25
    #define HREF_GPIO_NUM 23
    #define PCLK_GPIO_NUM 22
    
    static camera_config_t camera_config = { 
      .pin_pwdn = PWDN_GPIO_NUM,
      .pin_reset = RESET_GPIO_NUM,
      .pin_xclk = XCLK_GPIO_NUM, 
      .pin_sscb_sda = SIOD_GPIO_NUM,  
      .pin_sscb_scl = SIOC_GPIO_NUM,
         
      .pin_d7 = Y9_GPIO_NUM,
      .pin_d6 = Y8_GPIO_NUM,
      .pin_d5 = Y7_GPIO_NUM, 
      .pin_d4 = Y6_GPIO_NUM,
      .pin_d3 = Y5_GPIO_NUM,
      .pin_d2 = Y4_GPIO_NUM,  
      .pin_d1 = Y3_GPIO_NUM,
      .pin_d0 = Y2_GPIO_NUM,
      .pin_vsync = VSYNC_GPIO_NUM,
      .pin_href = HREF_GPIO_NUM,
      .pin_pclk = PCLK_GPIO_NUM,
    
      .xclk_freq_hz = 20000000,
      .ledc_timer = LEDC_TIMER_0,
      .ledc_channel = LEDC_CHANNEL_0,
      
      .pixel_format = PIXFORMAT_JPEG,
      .frame_size = FRAMESIZE_UXGA,
      .jpeg_quality = 12,
      .fb_count = 1,
    };
    
    esp_err_t camera_init(){ 
        //initialize the camera
        esp_err_t err = esp_camera_init(&camera_config);
        if (err != ESP_OK) { 
            Serial.print("Camera Init Failed");
            return err;
        }
        sensor_t * s = esp_camera_sensor_get();
        //initial sensors are flipped vertically and colors are a bit saturated
        if (s->id.PID == OV2640_PID) { 
    // s->set_vflip(s, 1);//flip it back
    // s->set_brightness(s, 1);//up the blightness just a bit
    // s->set_contrast(s, 1);
        }
      
        Serial.print("Camera Init OK");
        return ESP_OK;
    }
    
    void setup() { 
      Serial.begin(115200);
    
      camera_init();
    
      pinMode(KEY_PIN, INPUT_PULLUP); //设置按键管脚输入上拉模式
      
      Serial.print("sys is running!");
    }
    int buttonState = 0;
    int btnHold = 0;
    
    void loop() { 
      
        buttonState = digitalRead(KEY_PIN); //读取按键返回状态值
        if (buttonState == LOW && btnHold == 0) 
        {  // 若按键被按下
            delay(100); //等待跳过按键抖动的不稳定过程
            if (buttonState == LOW) // 若按键被按下
            {   
              	btnHold = 1; // 不支持连按标志
    
              	//acquire a frame
              	camera_fb_t * fb = esp_camera_fb_get();
              	if (!fb) 
              	{ 
                  	Serial.print( "Camera capture failed");
              	} 
              	else 
              	{ 
                  	//Serial.printf("width:%d, height:%d, format:%d, len:%d\r\n", fb->width, fb->height, fb->format, fb->len);
                   	Serial.write(fb->buf, fb->len);
                    
                   	esp_camera_fb_return(fb); 
              	}
             }
        }
        if(buttonState == HIGH)
        { 
            btnHold = 0;
        }
    }

## Qt上位机显示串口图片 ##

使用Qt编写串口上位机用于显示图片

QSerialPort *serialPort;
    
    QByteArray byteArray;
    
    QPixmap pixmap;
    
    QByteArray g_photo_data;
    
    // 串口接收数据
    void MainWindow::slotReadData()
    { 
        QByteArray temp = serialPort->readAll();
    
        if(!temp.isEmpty())
        { 
            ui->textEditReceive->append(temp);
    
            g_photo_data.append(temp);
        }
    }
    // 显示图片按钮
    void MainWindow::on_pushButtonStart_clicked()
    { 
        QImage image;
        bool flag = image.loadFromData((const uchar *)g_photo_data.data(),g_photo_data.size());
    
        if(flag)
        { 
            QPixmap pixmap=QPixmap::fromImage(image);
            ui->labelImage->setPixmap(pixmap);
            g_photo_data.clear();
        }
    }

## 效果图 ##

ESP32 cam实物图：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70 1]Qt上位机软件图：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70 2]

[Link 1]: https://github.com/espressif/esp32-camera/blob/master/driver/include/sensor.h
[Link 2]: https://blog.csdn.net/yun_hen/article/details/78135122
[Link 3]: https://blog.csdn.net/u012837895/article/details/84434047
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191211225258453.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/2019121300083043.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20191213000528531.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWVmeXVhbi5ibG9nLmNzZG4ubmV0,size_16,color_FFFFFF,t_70