ov7725摄像头调试经验-寄存器配置

     之前调过一款摄像头,是MT9V034, 最近在调的是OV7725摄像头,感觉OV7725摄像头比MT9V034要难,特别是寄存器配置,要想玩转一款摄像头,必须要熟悉它的寄存器配置,而且要亲自去调试,然后才能对它有很好的理解。下面是自己的一点见解,可能不完全对,不过希望对初学者有所帮助吧。

一、将所有寄存器的值复位到默认值状态。

   寄存器地址       寄存器名称      寄存器值

     0x12                COM7                   0x80      //复位

二、 设置图像输出格式。

   寄存器地址       寄存器名称      寄存器值

    0x12                  COM7               0X40    //QVGA(320*240 ),YUV输出格式

    0x29                  HOutSize      0X50 //    QVGA(320*240), 0x28  (160)

    0x2C                 VOutSize       0X78 //   QVGA (320*240),0x3C  (120)

    0x17                  HSTART        0X3F     //QVGA(320*240 )

    0X18                 HSIZE             0X50     //QVGA(320*240 )

    0X19                 VSTRT            0X03   //QVGA(320*240 )

    0X20                 VSIZE             0X78     //QVGA(320*240 )

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12 COM7 00 RW Common Control 7
Bit[7]: SCCB Register Reset
0: No change
1: Resets all registers to default values
Bit[6]: Resolution selection
0: VGA
1: QVGA
Bit[5]: BT.656 protocol ON/OFF selection
Bit[4]: Sensor RAW
Bit[3:2]: RGB output format control
00: GBR4:2:2
01: RGB565
10: RGB555
11: RGB444
Bit[1:0]: Output format control
00: YUV
01: Processed Bayer RAW
10: RGB
11: Bayer RAW

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三、和图片曝光强弱有关的寄存器

1、自动曝光

   寄存器地址       寄存器名称      寄存器值
  0X0D                     COM4           0X40     //整个窗口进行自动曝光

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0D COM4 41 RW Common Control 4
Bit[7:6]: PLL frequency control
00: Bypass PLL
01: PLL 4x
10: PLL 6x
11: PLL 8x
Bit[5:4]: AEC evaluate window
00: Full window
01: 1/2 window
10: 1/4 window
11: Low 2/3 window
Bit[3:0]: Reserved
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0x13                   COM8             0XFF       //     打开自动增益(AGC)、自动白平衡(AWB)、自动曝光(AEC)

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13 COM8 8F RW Common Control 8
Bit[7]: Enable fast AGC/AEC algorithm
Bit[6]: AEC - Step size limit
0: Step size is limited to vertical blank
1: Unlimited step size
Bit[5]: Banding filter ON/OFF
Bit[4]: Enable AEC below banding value
Bit[3]: Fine AEC ON/OFF control
Bit[2]: AGC Enable
Bit[1]: AWB Enable
Bit[0]: AEC Enable
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0X24                  AEW                  0X40                    //控制自动曝光强弱


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24 AEW 75 RW AGC/AEC - Stable Operating Region (Upper Limit)
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0X25                  AEB                  0X15                     //控制自动曝光的强弱

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25 AEB 63 RW AGC/AEC - Stable Operating Region (Lower Limit)
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0X26                   VPT                   0X32                //快速模式工作区

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26 VPT D4 RW AGC/AEC Fast Mode Operating Region
Bit[7:4]: High nibble of upper limit of fast mode control zone
Bit[3:0]: High nibble of lower limit of fast mode control zone
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0XA6                 SDE                0X24                 //使能控制图片亮暗的寄存器


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A6 SDE 00 RW Special Digital Effect Control
Bit[7]: Reserved
Bit[6]: Negative image enable
Bit[5]: Gray scale image enable
Bit[4]: V fixed value enable
Bit[3]: U fixed value enable
Bit[2]: Contrast/Brightness enable
Bit[1]: Saturation enable
Bit[0]: Hue enable

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0X9B              BRIGHT               0X08           //定义自动曝光时图片的亮度增益,此值越大,图片越亮


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9B BRIGHT 00 RW Brightness Control

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0XAB            SIGN                   0X06         //定义BRIGHT   的高位是正数,还是负数,如果为0x0e,则图片亮度是负的;0-255,图片越来越亮;0 ~ -127,图片越来越亮

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AB SIGN 06 RW Sign Bit for Hue and Brightness
Bit[7:4]: Reserved
Bit[3]: Brightness sign bit
Bit[2]: Reserved
Bit[1]: Sign bit for HueSin (in Cr’ equation)
Bit[0]: Sign bit for HueSin (in Cb’ equation)

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2、手动曝光

   寄存器地址       寄存器名称      寄存器值
  0X0D                     COM4           0X40     //整个窗口进行自动曝光

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0D COM4 41 RW Common Control 4
Bit[7:6]: PLL frequency control
00: Bypass PLL
01: PLL 4x
10: PLL 6x
11: PLL 8x
Bit[5:4]: AEC evaluate window
00: Full window
01: 1/2 window
10: 1/4 window
11: Low 2/3 window
Bit[3:0]: Reserved

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0x13                   COM8             0Xcc      //     关闭自动曝光(AEC)

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13 COM8 8F RW Common Control 8
Bit[7]: Enable fast AGC/AEC algorithm
Bit[6]: AEC - Step size limit
0: Step size is limited to vertical blank
1: Unlimited step size
Bit[5]: Banding filter ON/OFF
Bit[4]: Enable AEC below banding value
Bit[3]: Fine AEC ON/OFF control
Bit[2]: AGC Enable
Bit[1]: AWB Enable
Bit[0]: AEC Enable

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0x08                AECH              0X00   //曝光值得高8位    ,改变AECH和AEC的值,可以改变图片亮度

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08 AECH 00 RW Exposure Value – AEC MSBs
Bit[7:0]: AEC[15:8] (see register
AECfor AEC[7:0
Automatically updated based on chip output format
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0x10                 AEC                0X40   //曝光值得低8位

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10 AEC 40 RW Exposure Value
Bit[7:0]: AEC[7:0] (see register
AECHfor AEC[15:8])

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