无线图像（视频）传输系统ARM9+Atmega16+OV7620+nrf2(3)

 OV7620支持的像素是：VGA（640*480）、QVGA(320*240)，我用的是QVGA模式（配合液晶屏显示）。使用OV7620关键还是正确配置其内部寄存器，还有就是SCCB数据传输协议的实现。

      首先有必要说下OV7620所支持的图像格式，因为，我对图像这块不熟悉，这里只说明OV支持的几种输出格式，以及相关寄存器的配置。

      RGB16/8 bit ,这些格式都不是真正的RGB数据流，而是Bayer矩阵，所以在终端显示时，必须将Bayer矩阵转换为RGB。转换的核心思想是通过插值算法将Bayer矩阵中的每个像素值（一个字节）转换为RGB三个字节（我不懂图像，只能说出方法，具体算法后面我会贴出）。

      本次采用的是RGB raw16 bit 模式，由于OV7620只引出了Y通道，所以配置为one line mode(这里出现了问题，明明RGB三个分量都有，但是通过插值后显示出来的尽然还是灰度图像，后面再分析原因)。下面贴出OV7620相关寄存器的配置：

 unsigned char reg_12_w_reset[2]={0x12,0x80};//先清零
 
 unsigned char reg_11_w[2]={0x11,0x00};  //配置PCLK速率  PCLK=(CLK_input/(CLK<5:0>+1)*2)),本次为1/2时钟频率
 unsigned char reg_12_w[2]={0x12,0x2c};  //使能AGC，选择raw data outtput,并且使能自动白平衡
 unsigned char reg_14_w[2]={0x14,0x24};//QVGA digital output format  ,RGB gamma  on
 unsigned char reg_28_w[2]={0x28,0xa0}; //one-line RGB data format     ,select Progressive scan mode

         下面是Bayer转RGB24的算法（在液晶屏上显示时还要转为RGB16）:

 void  bayer2rgb24(unsigned char *dst, unsigned char *src, long WIDTH, long HEIGHT)
{
    long int i;
    unsigned char *rawpt, *scanpt;
    long int size;
 
    rawpt = src;
    scanpt = dst;
    size = WIDTH*HEIGHT;
 
    for ( i = 0; i < size; i++ )
    {
  if ( (i/WIDTH) % 2 == 0 )      //奇数行
  {
   if ( (i % 2) == 0 )      //奇数列
   {
    /* B */
    if ( (i > WIDTH) && ((i % WIDTH) > 0) )
    {
     *scanpt++ = ((long int)*(rawpt-WIDTH-1)+(long int)*(rawpt-WIDTH+1)+
      (long int)*(rawpt+WIDTH-1)+(long int)*(rawpt+WIDTH+1))/4; /* R */
     *scanpt++ = ((long int)*(rawpt-1)+(long int)*(rawpt+1)+
      (long int)*(rawpt+WIDTH)+(long int)*(rawpt-WIDTH))/4; /* G */
     *scanpt++ = *rawpt;     /* B */
    }
    else       /* first line or left column */
    {
     
     *scanpt++ = *(rawpt+WIDTH+1);  /* R */
     *scanpt++ = ((long int)*(rawpt+1)+(long int)*(rawpt+WIDTH))/2; /* G */
     *scanpt++ = *rawpt;    /* B */
    }
   }
   else
   {
    /* (B)G */
    if ( (i > WIDTH) && ((i % WIDTH) < (WIDTH-1)) )
    {
     *scanpt++ = ((long int)*(rawpt+WIDTH)+(long int)*(rawpt-WIDTH))/2; /* R */
     *scanpt++ = *rawpt;     /* G */
     *scanpt++ = ((long int)*(rawpt-1)+(long int)*(rawpt+1))/2;  /* B */
    }
    else /* first line or right column */
    {
     
     *scanpt++ = *(rawpt+WIDTH); /* R */
     *scanpt++ = *rawpt;  /* G */
     *scanpt++ = *(rawpt-1); /* B */
    }
   }
  }
  else    //偶数行
  {
            if ( (i % 2) == 0 )  //奇数列
      {
       /* G(R) */
       if ( (i < (WIDTH*(HEIGHT-1))) && ((i % WIDTH) > 0) )
       {
        *scanpt++ = ((long int)*(rawpt-1)+(long int)*(rawpt+1))/2;  /* R */
        *scanpt++ = *rawpt;     /* G */
        *scanpt++ = ((long int)*(rawpt+WIDTH)+(long int)*(rawpt-WIDTH))/2; /* B */
       }
       else
       {
        /* bottom line or left column */
        *scanpt++ = *(rawpt+1);  /* R */
        *scanpt++ = *rawpt;   /* G */
        *scanpt++ = *(rawpt-WIDTH);  /* B */
       }
      }
      else
      {
       /* R */
       if ( i < (WIDTH*(HEIGHT-1)) && ((i % WIDTH) < (WIDTH-1)) )
       {
        *scanpt++ = *rawpt;     /* R */
        *scanpt++ = ((long int)*(rawpt-1)+(long int)*(rawpt+1)+
         (long int)*(rawpt-WIDTH)+(long int)*(rawpt+WIDTH))/4; /* G */
        *scanpt++ = ((long int)*(rawpt-WIDTH-1)+(long int)*(rawpt-WIDTH+1)+
         (long int)*(rawpt+WIDTH-1)+(long int)*(rawpt+WIDTH+1))/4; /* B */
       } else {
        /* bottom line or right column */
        *scanpt++ = *rawpt;    /* R */
        *scanpt++ = ((long int)*(rawpt-1)+(long int)*(rawpt-WIDTH))/2; /* G */
        *scanpt++ = *(rawpt-WIDTH-1);  /* B */
       }
      }
  }
  rawpt++;
    }
}